# Applications from Scientific Engineering

## Modulation of Turbulent Properties in a Spray Flame Burning n-Heptane: Direct Numerical Simulation

Spray evaporation and burning in a turbulent environment is a configuration found in many practical applications, such as diesel engines, direct-injection gasoline engines, gas turbines, etc. Understanding the physical process involved in this combustion process will help improving the combustion efficiency of these devices and, therefore, reduce their emissions. Direct numerical simulation (DNS) is a very attractive tool to investigate in all details the underlying processes since it is able to capture and resolve all scales in the system. In this project, evaporation, ignition, and mixing are investigated in both temporally- and spatially-evolving jets, using DNS.

**Principal Investigator: **Dominique Thévenin, Lab. of Fluid Dynamics and Technical Flows, University of Magdeburg "Otto von Guericke", Magdeburg (Germany)

**HPC Platform:** SuperMUC of LRZ - **Date published:** October 2016

**More: Modulation of Turbulent Properties in a Spray Flame Burning n-Heptane: Direct Numerical Simulation …**

## Turbulent Convection at Very Low Prandtl Numbers

In many turbulent convection flows in nature and technology the thermal diffusivity is much higher than the kinematic viscosity which means that the Prandtl number is very low. Laboratory experiments in very low-Prandtl-number convection have to be conducted in liquid metals which are inaccessible for laser imaging techniques and require analysis by ultrasound or X-rays. Researchers of the TU Ilmenau and the Occidental College Los Angeles ran direct numerical simulations of this regime of turbulent convection at high Rayleigh numbers to reveal the full 3D structure of temperature and velocity fields.

**Principal Investigator: **Jörg Schumacher, Technische Universität Ilmenau (Germany)

**HPC Platform:** JUQUEEN of JSC - **Date published:** October 2016

**More: Turbulent Convection at Very Low Prandtl Numbers …**

## APAM – Aquatic Purification Assisted by Membranes

The electro-dialysis process is an efficient desalination technique that uses ion exchange membranes to produce clean water from seawater. This process involves different physical phenomena like fluid dynamics, electrodynamics and diffusive mass-transport along with their interactions. Rigorous assessment of those interactions, especially those near the membranes, are only possible through large-scale coupled simulations. The aim of the APAM compute time project is the detailed flow simulation in this application to understand the effect of different spacer structures between the membranes in this process.

**Principal Investigator: **Sabine Roller, University of Siegen, Institute of Simulation Techniques and Scientific Computing (Germany)

**HPC Platform:** Hazel Hen of HLRS - **Date published:** October 2016

**More: APAM – Aquatic Purification Assisted by Membranes …**

## Investigation of the Flow Through the Intake Port of an IC-Engine Using High-Resolution LES

A numerical research project, run on Hornet of HLRS, focused on the grid of internal combustion (IC) engines in the vicinity of the intake valve and its effect on the simulation results. The overall goal was to develop a methodology for a quantitative comparison of different results in terms of the intake jet as well as the identification of crucial mesh regions.

**Principal Investigator:** Christian Hasse, Numerical Thermo-Fluid Dynamics, TU Bergakademie Freiberg (Germany)

**HPC Platform:** Hornet of HLRS - **Date published:** September 2016

**More: Investigation of the Flow Through the Intake Port of an IC-Engine Using High-Resolution LES …**

## Two-Phase-Flows in Francis and Pump Turbines

In the last decades, hydraulic machines have experienced a continual extension of the operating range in order to integrate other renewable energy sources into the electrical grid. When operated at off-design conditions, the turbine experiences cavitation which may reduce the power output and can cause severe damage in the machine. Cavitation simulations are suitable to give a better understanding of the physical processes acting at off-design conditions. The goal of this project is to give an insight in the capabilities of two-phase simulations for hydraulic machines and determine the range for safe operation.

**Principal Investigator:** Jonas Wack, Institute of Fluid Mechanics and Hydraulic Machinery, University of Stuttgart (Germany)

**HPC Platform:** Hazel Hen of HLRS - **Date published:** July 2016

**More: Two-Phase-Flows in Francis and Pump Turbines …**

## Investigation of the Influences of Gaps at the Runner Blade for an Axial Turbine Using Hybrid Turbulence Models

The operation range of hydraulic turbines is increasing more and more to guarantee the power system stability of the electric grid due to the increased amount of electric power generated by unregulated renewable energy like wind and photovoltaic. Therefore, hydraulic turbines are operated in off-design conditions where highly transient phenomena can occur. Standard approaches which are used for the design process of hydraulic machines are no longer suitable to predict the correct flow field in these operating points. Advanced turbulence models and high mesh resolutions are applied to increase the accuracy of the simulations.

**Principal Investigator:** Bernd Junginger, Institute of Fluid Mechanics and Hydraulic Machinery, University of Stuttgart (Germany)

**HPC Platform:** Hazel Hen of HLRS - **Date published:** June 2016

**More: Investigation of the Influences of Gaps at the Runner Blade for an Axial Turbine Using Hybrid Turbulence Models …**

## Numerical Investigation of Ship-Propeller Cavitation with Full Description of Shock-Wave Dynamics

A project of scientists of the Institute of Aerodynamics and Fluid Mechanics at the Technische Universität München focused on the numerical investigation of cavitating flow in the context of ship propellers. A key aspect of this project was to develop the ability to assess local flow aggressiveness and to quantify the potential of material erosion.

**Principal Investigator:** Bernd Budich, Technische Universität München (Germany)

**HPC Platform:** SuperMUC of LRZ - **Date published:** June 2016

**More: Numerical Investigation of Ship-Propeller Cavitation with Full Description of Shock-Wave Dynamics …**

## RBTC - Towards Ultimate Rayleigh-Benard and Taylor-Couette Turbulence

Rayleigh-Benard flow (the flow in a box heated from below and cooled from above) and Taylor-Couette flow (the flow between two counter-rotating cylinders) are the two paradigmatic systems in the physics of fluids, and many new concepts have been tested with them. Researchers from the Physics of Fluids group at the University of Twente have been carrying out simulations of these systems on HLRS supercomputers to try and improve our understanding of turbulence.

**Principal Investigator:** Detlef Lohse, University of Twente (The Netherlands)

**HPC Platform:** Hermit of HLRS - **Date published:** May 2016

**More: RBTC - Towards Ultimate Rayleigh-Benard and Taylor-Couette Turbulence …**

## Lagrangian **S**pace-**Ti**me Methods for **Mul**ti-Fluid Problems on **U**nstructured Me**s**hes (STiMulUs)

Researchers leveraged the computing power of SuperMUC for the development of finite volume Lagrangian numerical schemes on multidimensional unstructured meshes for fluid dynamic problems. The numerical algorithms developed in project STiMulUs are designed to be high order accurate in space as well as in time, requiring even more information to be updated and recomputed continuously as the simulation goes on.

**Principal Investigator:** Walter Boscheri, Department of Civil, Environmental and Mechanical Engineering, University of Trento (Italy)

**HPC Platform:** SuperMUC of LRZ - **Date published:** May 2016

**More: Lagrangian Space-Time Methods for Multi-Fluid Problems on Unstructured Meshes (STiMulUs) …**

## Discontinuous Galerkin Methods for Detached Eddy Simulation

Despite the great success of current state-of-the-art fluid flow solvers, the continuing development of computing hardware necessitates new numerical methods for flow simulations. High order methods on unstructured grids like Discontinuous Galerkin discretisations deliver highly accurate results and allow for unprecedented parallelisation efficiency at huge numbers of cores. The project aims to transfer the infrastructure technology (overlapping Chimera grids, mesh movement and deformation, convergence acceleration) from conventional to such advanced solvers to allow application to relevant engineering problems like helicopter simulations in the mid-term future.

**Principal Investigator:** Manuel Keßler, Institut für Aerodynamik und Gasdynamik (IAG), Universität Stuttgart (Germany)

**HPC Platform:** Hornet and Hazel Hen of HLRS - **Date published:** March 2016

**More: Discontinuous Galerkin Methods for Detached Eddy Simulation …**

## High Fidelty Simulations of Rotorcraft Aerodynamics and Aeroacoustics (HELISIM)

The helicopter and aeroacoustics group of IAG runs extensive aerodynamics and aeromechanics simulations of rotorcraft in order to understand not only basic parameters as power requirements or loads on the rotor blades but also to predict acoustic footprints and gain a deeper insight into the interactions between different helicopter components. For this purpose, the group runs simulation setups on HLRS supercomputer Hazel Hen of a magnitude beyond 200 million cells with fifth order accuracy and even up to half a billion cells for selected cases, delivering results directly comparable to real flight test data at unparalleled accuracy.

**Principal Investigator:** Manuel Keßler, Institut für Aerodynamik und Gasdynamik (IAG), Universität Stuttgart (Germany)

**HPC Platform:** Hazel Hen of HLRS - **Date published:** March 2016

**More: High Fidelty Simulations of Rotorcraft Aerodynamics and Aeroacoustics (HELISIM) …**

## Investigation of Delta Wing Time Dependent Flow Characteristics with Lattice-Boltzmann Method

The project Investigation of Delta Wing Time Dependent Flow Characteristics with Lattice-Boltzmann Method is carried out by the Technische Hochschule Ingolstadt, Faculty of Mechanical Engineering, at the High Performance Computing Center Stuttgart. It focuses on the numerical investigation of the delta wing flow under various aspects such as sweep angle variation, sharp or round leading edges, as well as high and lower Reynolds numbers with a Lattice-Boltzmann PowerFLOW solver provided by Exa.

**Principal Investigator:** Erol Oezger, Technische Hochschule Ingolstadt (Germany)

**HPC Platform:** Hermit and Hornet of HLRS - **Date published:** March 2016

**More: Investigation of Delta Wing Time Dependent Flow Characteristics with Lattice-Boltzmann Method …**

## Direct Numerical Simulation of an Adverse Pressure Gradient Turbulent Boundary Layer

An international research project aimed at investigating the structure and dynamics of wall-bounded turbulence in adverse pressure gradient environments has resulted in the first Direct Numerical Simulation (DNS) of a self-similar turbulent boundary layers (TBL) in a strong adverse pressure gradient (APG) environment at the verge of separation up to a Reynolds number based on the momentum thickness of 10^{4}.

**Principal Investigator:** Javier Jiménez, Universidad Politécnica de Madrid (Spain)

**HPC Platform:** SuperMUC of LRZ - **Date published:** February 2016

**More: Direct Numerical Simulation of an Adverse Pressure Gradient Turbulent Boundary Layer …**

## Fully-Resolved, Finite-Size Particles in Statistically Stationary, Homogeneous Turbulence

Turbulent flow seeded with solid particles is encountered in a number of natural and man-made systems. Many physical effects occurring when the fluid and the solid phase interact strongly so far have obstinately resisted analytical and experimental approaches – sometimes with far reaching consequences in various practical applications. Using SuperMUC, researchers simulated with unprecedented detail the turbulent flow in an unbounded domain in the presence of suspended, heavy, solid particles in order to understand and describe the dynamics of such particulate flow systems with sufficient accuracy.

**Principal Investigator:** Markus Uhlmann, Karlsruhe Institute of Technology (Germany)

**HPC Platform:** SuperMUC of LRZ - **Date published:** February 2016

**More: Fully-Resolved, Finite-Size Particles in Statistically Stationary, Homogeneous Turbulence …**

## High-Resolution Numerical Analysis of Turbulent Flow in Straight Ducts with Rectangular Cross-Section

Researchers investigated the mechanism of secondary flow formation in open duct flow where rigid/rigid and mixed (rigid/free-surface) corners exist. Employing direct numerical simulations (DNS) on HLRS high performance computing system Hornet, the scientists aimed at generating high-fidelity data in closed and open duct flows by means of pseudo-spectral DNS and at analysing the flow fields with particular emphasis on the dynamics of coherent structures.

**Principal Investigator:** Markus Uhlmann, Karlsruhe Institute of Technology (Germany)

**HPC Platform:** Hornet of HLRS - **Date published:** February 2016

**More: High-Resolution Numerical Analysis of Turbulent Flow in Straight Ducts with Rectangular Cross-Section …**

## Direct Numerical Simulations of Cloud Cavitation Collapse

Leveraging the petascale computing power of HPC system JUQUEEN of the Jülich Supercomputing Centre, researchers at the Chair of Computational Science at ETH Zurich performed unprecedented large-scale simulations of cloud cavitation collapse with up to 75’000 vapor cavities on resolutions of up to 0.5 trillion mesh cells and 25’000 time steps.

**Principal Investigator:** Petros Koumoutsakos, Computational Science & Engineering Laboratory, ETH Zurich (Switzerland)

**HPC Platform:** JUQUEEN of JSC - **Date published:** January 2016

**More: Direct Numerical Simulations of Cloud Cavitation Collapse …**

## Direct Numerical and Large Eddy Simulation of Wall-Bounded Flows for Aeroacoustic Source Term Identification

In order to gain a deeper understanding of the aerodynamic noise generation mechanisms and transmission for automotive applications, researchers from the Universität Erlangen leveraged HPC system SuperMUC of LRZ to develop a hybrid aeroacoustic method. The turbulent flow over a forward-facing step served as a test case for the final validation of a hybrid scheme for the computation of broadband noise, as caused typically by turbulent flows.

**Principal Investigator:** Christoph Scheit, Lehrstuhl für Prozessmaschinen und Anlagentechnik, Friedrich-Alexander Universität Erlangen-Nürnberg (Germany)

**HPC Platform:** SuperMUC of LRZ - **Date published:** January 2016

**More: Direct Numerical and Large Eddy Simulation of Wall-Bounded Flows for Aeroacoustic Source Term Identification …**

## Large Eddy Simulation of a Pseudo-Shock System Within a Laval Nozzle

Researchers of the Technische Universität München conducted large-eddy simulations (LES) on HPC system SuperMUC of LRZ for numerical investigations of a pseudo-shock system. These pseudo-shock systems influence the reliability and performance of a wide range of flow devices, such as ducts and pipelines in the field of process engineering and supersonic aircraft inlets. Thus, the optimization of pseudo-shock systems is of great academic and commercial interest.

**Principal Investigator: **Stefan Hickel, Technische Universität München (Germany)

**HPC Platform:** SuperMUC of LRZ - **Date published:** December 2015

**More: Large Eddy Simulation of a Pseudo-Shock System Within a Laval Nozzle …**

## Simulation of Shock-Wave/Boundary-Layer Interaction Using Conservative Finite-Differences

Shock-wave/boundary-layer interactions (SBLIs) play an important part in many engineering applications. They are common in internal and external aerodynamic flows. However, numerical treatment of such SBLIs is difficult as the important flow features place competing demands on the applied numerical algorithms. Using the HPC infrastructure provided by the HLRS, scientists of the Technische Universität Berlin performed a detailed direct numerical simulation of a transonic SBLI creating a detailed numerical database this way which is now available for further detailed studies.

**Principal Investigator:** Jörn Sesterhenn, CFD - Technische Universität Berlin (Germany)

**HPC Platform:** Hermit of HLRS - **Date published:** November 2015

**More: Simulation of Shock-Wave/Boundary-Layer Interaction Using Conservative Finite-Differences …**

## Simulation of Fluid-Particle Interaction in Turbulent Flows

Within the framework of a research project which aims at reducing the emission of CO_{2} by conventional coal-fired power plants through oxy-fuel combustion, scientists of the RWTH Aachen University simulated the heating processes of coal dust in order to gain a better understanding of the conditions causing carbon dust to ignite in an oxygen-carbon dioxide atmosphere. Since carbon particles are of irregular, non-spherical shape their motion is difficult to predict, thus simulations of large quantities of fully dissolved carbon particles moving freely in a turbulent flow require the availability of petascale HPC systems like Hazel Hen.

**Principal Investigator:** Wolfgang Schröder, Institute of Aerodynamics, RWTH Aachen University (Germany)

**HPC Platform:** Hazel Hen of HLRS - **Date published:** November 2015

**More: Simulation of Fluid-Particle Interaction in Turbulent Flows …**

## Fluid-Structure Interaction of Thin Structures in Turbulent Flows

Fluid-Structure Interaction is a topic of major interest in many engineering fields. The significant growth of the computational capabilities allows solving more complex coupled problems, whereby the physical models get closer to reality. In order to simulate practically relevant light-weight structural systems in turbulent flows, scientists of the Helmut-Schmidt-University in Hamburg developed and implemented an original computational methodology especially for thin flexible structures in turbulent flows.

**Principal Investigator:** Michael Breuer, Department of Fluid Mechanics, Helmut-Schmidt-University, Hamburg (Germany)

**HPC Platform:** SuperMUC of LRZ - **Date published:** November 2015

**More: Fluid-Structure Interaction of Thin Structures in Turbulent Flows …**

## NURESAFE – Nuclear Reactor Safety Simulation Platform

This project, for which HPC system Hermit of the High Performance Computing Center Stuttgart served as computing platform, is part of the NURESAFE initiative for nuclear safety. The objective was to develop a global modelling framework for multi-scale core thermal-hydraulics in Pressurized Water Reactors (PWR) as understanding heat transfer phenomena in turbulent bubbly flows is of great interest for the scientist community and for the industry.

**Principal Investigator:** Dr. Sylvain Reboux, ASCOMP AG, Zurich/Switzerland

**HPC Platform:** Hermit of HLRS - **Date published:** October 2015

**More: NURESAFE – Nuclear Reactor Safety Simulation Platform …**

## Simulation of Aeroacoustic Feedback Phenomena on a Side-View Mirror

In order to analyse aeroacoustic noise generation processes, researchers from the Institute for Aerodynamics and Gas Dynamics performed high fidelity, large-scale flow and acoustic computations using the discontinuous Galerkin spectral element method on the HPC system Hornet at the High Performance Computing Center Stuttgart (HLRS). The aim of this investigation is to gain insight into the tonal noise generation process of a side-view mirror.

**Principal Investigator:** Claus-Dieter Munz, Institut für Aerodynamik und Gasdynamik, Universität Stuttgart (Germany)

**HPC Platform:** Hornet of HLRS - **Date published:** October 2015

**More: Simulation of Aeroacoustic Feedback Phenomena on a Side-View Mirror …**

## Large Eddy Simulation of a Scramjet Strut Injector with Pilot Injection

A scramjet is an air breathing jet engine for hypersonic flight velocities of about ten to twenty times the speed of sound. Combustion, too, takes place at supersonic flow velocity, which requires a fast mixing of fuel and compressed airflow to enable combustion during the very short residence time of the reactants in the combustion chamber. To analyze the flame stabilization in the combustion chamber through a pilot injection of hydrogen and air at the base of the strut injector, researchers from the Technische Universität München (TUM) performed large-eddy simulations for a generic strut-injector geometry based on an experimental setup at the TUM.

**Principal Investigator:** Stefan Hickel, Technische Universität München (Germany)

**HPC Platform:** Hermit of HLRS - **Date published:** September 2015

**More: Large Eddy Simulation of a Scramjet Strut Injector with Pilot Injection …**

## Scalable Multi-Physics with waLBerla

Researchers of the University of Erlangen applied the waLBerla Framework, a widely applicable lattice Boltzmann simulation code, on HPC system SuperMUC of LRZ to test the suitability of the software framework for different Computational Fluid Dynamics applications: One project focused on investigating collective swarming behavior of numerous self-propelled microorganisms at low Reynolds numbers, a second project implemented within waLBerla was the simulation of electron beam melting, while a third simulated the separation of charged macromolecules in electrolyte solutions inside channels of dimensions relevant for lab-on-a-chip (LoC) systems.

**Principal Investigator:** Harald Köstler, Lehrstuhl Informatik 10 (Systemsimulation), Universität Erlangen-Nürnberg (Germany)

**HPC Platform:** SuperMUC of LRZ - **Date published:** August 2015

**More: Scalable Multi-Physics with waLBerla …**

## Direct Numerical Simulation of a Spatially Developing Mixing Layer With Temperature Gradient

Direct numerical simulation (DNS) of turbulent mixing layers has been possible only in relatively recent times. In an ambitious project using HPC system JUQUEEN of JSC, scientists analysed the process of mixing layer formation in a flow configuration with sizeable compressibility effects by numerically reproducing the flow conditions of a well documented flow case with two turbulent streams. Large-scale direct numerical simulation were performed in a wide computational domain which included the two upstream turbulent boundary layers developing on the two sides of a zero-thickness splitter plate and their early merging region. The complexity of the flow, the extent of the computational box and the mesh size made the study extremely challenging in terms of CPU hours and memory requirements.

**Principal Investigator: ** Francesco Grasso, Institut Aérotechnique, Conservatoire National des Arts et Métiers, Saint-Cyr-l'Ecole (France)

**HPC Platform:** JUQUEEN of JSC - **Date published:** July 2015

**More: Direct Numerical Simulation of a Spatially Developing Mixing Layer With Temperature Gradient …**

## The Multicore Challenge: Petascale DNS of a Spatially-Developing Supersonic Turbulent Boundary Layer up to High Reynolds Numbers using DGSEM

Scientists of the Institute of Aerodynamics and Gas Dynamics of the University of Stuttgart conducted a Direct Numerical Simulation of a spatially-developing supersonic turbulent boundary layer up to Re_{Θ}=3878. For this purpose, they used the discontinuous Galerkin spectral element method (DGSEM), a very efficient DG formulation that is specifically tailored to HPC applications. It allowed the researchers to efficiently exploit the entire computational power available on the HLRS Cray XC40 supercomputer Hornet and to run the simulation with 93,840 processors without any performance losses.

**Principal Investigator: **Claus-Dieter Munz, Institute of Aerodynamics and Gas Dynamics, University of Stuttgart

**HPC Platform:** Hornet of HLRS - **Date published:** June 2015

**More: The Multicore Challenge: Petascale DNS of a Spatially-Developing Supersonic Turbulent Boundary Layer up to High Reynolds Numbers using DGSEM …**

## Large-Eddy Simulation of a Helicopter Engine Jet

A research team of the Institute of Aerodynamics (AIA) of the RWTH Aachen University leveraged the petascale computing power of the HPC system Hornet for large-scale simulation runs which used the entirety of the system’s available 94,646 compute cores. The project “Large-Eddy Simulation of a Helicopter Engine Jet” aimed at analysing the impact of internal perturbations due to geometric variations on the flow field and the acoustic field of a helicopter engine jet. For this purpose, the researchers conducted highly resolved large-eddy simulations based on hierarchically refined Cartesian meshes up to 1 billion cells over a time span of 300 hours.

**Principal Investigator: **Wolfgang Schröder, Institute of Aerodynamics, RWTH Aachen University (Germany)

**HPC Platform:** Hornet of HLRS - **Date published:** June 2015

**More: Large-Eddy Simulation of a Helicopter Engine Jet …**

## Prediction of the Turbulent Flow Field Around a Ducted Axial Fan

Exploiting the available computing capacities of supercomputer Hornet of the High Performance Computing Center Stuttgart, researchers from the Institute of Aerodynamics (AIA) of the RWTH Aachen University conducted a large-scale simulation run in their efforts to tackle the prediction of the acoustic field of a low pressure axial fan using computational aeroacoustics (CAA) methods. Goal of this project, which scaled to 92,000 compute cores of the HPC system Hornet, was to achieve a better understanding of the development of vortical flow structures and the turbulence intensity in the tip-gap of a ducted axial fan.

**Principal Investigator: **Wolfgang Schröder, Institute of Aerodynamics, RWTH Aachen University (Germany)

**HPC Platform:** Hornet of HLRS - **Date published:** June 2015

**More: Prediction of the Turbulent Flow Field Around a Ducted Axial Fan …**

## Ion Transport by Convection and Diffusion

A research team of the Institute of Simulation Techniques and Scientific Computing of the University of Siegen leveraged the petascale computing power of HPC system Hornet for their research project Ion Transport by Convection and Diffusion. This large-scale simulation project stressed the available capacities of the HLRS supercomputer to its full extent as the simulation involved the simultaneous consideration of multiple effects like flow through a complex geometry, mass transport due to diffusion and electrodynamic forces. Goal of this project was to achieve a better understanding of the electrodialysis desalination process in order to identify methods and possibilities of how to optimize it.

**Principal Investigator: **Sabine Roller, University of Siegen, Institute of Simulation Techniques and Scientific Computing

**HPC Platform:** Hornet of HLRS - **Date published:** May 2015

**More: Ion Transport by Convection and Diffusion …**

## Direct Numerical Simulation of the Gravitational Settling of Finite Size Particles in Homogeneous Flow

A research project addressed the fundamental mechanisms and processes involved in the dynamics of a large number of rigid particles settling under the influence of gravity in an initially quiescent fluid, as well the characteristics of the particle-induced flow field.

**Principal Investigator: ** Markus Uhlmann, Institute for Hydromechanics, Karlsruhe Institute of Technology/KIT (Germany)

**HPC Platform:** SuperMUC of LRZ - **Date published:** April 2015

**More: Direct Numerical Simulation of the Gravitational Settling of Finite Size Particles in Homogeneous Flow …**

## Numerical Simulation of Engine-Inlet Stall at Low Speed Range With Reynolds-Stress Turbulence Models

One of the major limiting factors of the flight operational range of transport aircraft is the inlet separation of engine. The overall aim of this project is to provide an efficient numerical method able to compute the large range of spectral scales present in flows during the separation process.

**Principal Investigator: **Daniela Gisele François, Institut für Strömungsmechanik, TU Braunschweig (Germany)

**HPC Platform: **Hermit of HLRS - **Date published: **April 2015

**More: Numerical Simulation of Engine-Inlet Stall at Low Speed Range With Reynolds-Stress Turbulence Models …**

## Aerodynamic Investigations of Vortex Dominated and Morphing Aircraft Configurations with Active and Passive Flow Control

For delta and diamond wing configurations, the flow field is typically dominated by large scale vortex structures, which originate from the wing leading-edges. With increasing angle of attack, the flow structures grow in size and become more and more unsteady. By use of active and passive flow control mechanisms, the vortex characteristics can be manipulated and controlled in some extent.

**Principal Investigator: ** Christian Breitsamter, AER/TU München (Germany)

**HPC Platform:** SuperMUC of LRZ - **Date published:** March 2015

**More: Aerodynamic Investigations of Vortex Dominated and Morphing Aircraft Configurations with Active and Passive Flow Control …**

## Dynamics of Multi-Component Fluid Dynamics in Porous Structures

Scientists of the University of Rome (“Tor Vergata”) and the University of Eindhoven aimed to perform a systematic investigation of multi-component and/or multi-phase flow dynamics in porous matrices adopting a bottom-up, multi-scale approach based on a Lattice Boltzmann Method (LBM).

**Principal Investigator: **Mauro Sbragaglia, University of Roma (Italy)

**HPC Platform: **Hermit of HLRS - **Date published:** March 2015

**More: Dynamics of Multi-Component Fluid Dynamics in Porous Structures …**

## DNS / LES Studies of Turbulent Flows Based on the Cumulant Lattice Boltzmann Approach

Scientists of the Technische Universität Braunschweig conduct Direct Navier-Stokes (DNS) and Large Eddy Simulation (LES) computations of turbulent flows which explicitly take into account specific pore scale geometries obtained from computer tomography imaging and do not use any explicit turbulence modeling.

**Principal Investigator:** Manfred Krafczyk, IRMB/TU Braunschweig (Germany)

**HPC Platform:** Hermit of HLRS - **Date published:** March 2015

**More: DNS / LES Studies of Turbulent Flows Based on the Cumulant Lattice Boltzmann Approach …**

## Aerodynamics and Aeroacoustics of Complex Geometry Hot Jets

With the projected demand for air transport set to double the world aircraft fleet by 2020 it is becoming urgent to take steps to reduce the environmental impact of take-off noise from aircraft. Scientists from the UK performed highly intensive Large Eddy Simulations (LES) of complex geometry jets with the major emphasis to use the LES CFD approach (Computational Fluid Dynamics) to enable improved prediction and to generate the necessary complex unsteady flow fields needed for acoustic modelling.

**Principal Investigator:** Richard Jefferson-Loveday, The University of Nottingham (U.K.)

**HPC Platform:** Hermit of HLRS - **Date published:** March 2015

**More: Aerodynamics and Aeroacoustics of Complex Geometry Hot Jets …**

## Cavitation Phenomena in Diesel Injection Systems

Modern Diesel injection systems exceed injection pressures of 2000 bar in order to meet current and future emission regulations. By accelerating the flow through an injection nozzle or throttle valve pressure in the liquid can drop below vapor pressure, initiating local evaporation (hydrodynamic cavitation). The advection of vapor cavities into regions where the static pressure of the surrounding liquid exceeds vapor pressure leads to a sudden re-condensation or collapse of vapor cavities. The surrounding liquid is accelerated towards the center of the cavities and strong shock waves are emitted. The resulting pressure loads can lead to material erosion. For optimization of future fuel injectors the ability to predict cavitation and cavitation erosion during early stages of the design is desirable.

**Principal Investigator: ** Christian Egerer, AER/TU München (Germany)

**HPC-Platform:** SuperMUC (LRZ), Hornet/Hermit (HLRS) - **Date published:** Feb. 2015

**More: Cavitation Phenomena in Diesel Injection Systems …**

## High-Amplitude Fluctuations of Velocity and Temperature Gradients in Turbulent Convection

An international team of scientists conducted high-precision spectral element simulations which resolved the fine-scale structure of turbulent Rayleigh-Bénard convection, in particular the statistical fluctuations of the temperature and velocity gradients.

**Principal Investigator:** Jörg Schumacher, TU Ilmenau (Germany)

**HPC Platform:** JUQUEEN of JSC - **Date published:** February 2015

**More: High-Amplitude Fluctuations of Velocity and Temperature Gradients in Turbulent Convection …**

## Multiscale Modelling of Particles in Suspension

A team of scientists from Germany, UK, US and Spain have developed a multiscale particle methods framework based on Smoothed Particle Hydrodynamics (SPH) and the stochastic Smoothed Dissipative Particle Dynamics (SDPD) to simulate the complex dynamics of submicron-sized colloidal and large non-colloidal particles suspended in Newtonian and non-Newtonian fluids.

**Principal Investigator:** Marc Ellero, Technische Universität München (Germany)

**HPC Platform:** SuperMUC of LRZ - ** Date published: ** February 2015

**More: Multiscale Modelling of Particles in Suspension …**

## Morphology–Transport Relationships for Packed Columns

By simulating fluid flow through computer-generated, confined sphere packings, a team of scientists from the Department of Chemistry at the Philipps-Universität Marburg correlate morphological parameters with transport coefficients.

**Principal Investigator:** Ulrich Tallarek, Philipps-Universität Marburg (Germany)

**HPC Platform:** JUQUEEN of JSC - **Date published:** November 2014

**More: Morphology–Transport Relationships for Packed Columns …**

## Numerical Investigation of Complex Multiphase Flows With Lagrangian Particle Methods

Scientists of the Institute of Aerodynamics and Fluid Mechanics of the Technische Universität München have developed a smoothed particle hydrodynamics (SPH) method to simulate complex multiphase flows with arbitrary interfaces and included a model for surface active agents.

**Principal Investigator:** Nikolaus A. Adams, TU München (Germany)

**HPC Platform:** SuperMUC of LRZ - **Date published:** October 2014

**More: Numerical Investigation of Complex Multiphase Flows With Lagrangian Particle Methods …**

## Direct Numerical Simulations of Impeller Driven Turbulence and Dynamo Action

The process, in which a magnetic field is amplified by the flow of an electrically conducting fluid such as liquid metal or plasma, known as dynamo action, is believed to be the origin of magnetic fields in the universe including the magnetic field of the earth. Laboratory experiments using liquid sodium try to investigate the underlying mechanisms. Direct numerical simulations of spatially and temporally resolved fields allow a detailed analysis of flow and magnetic field structures.

**Principal Investigator:** Rainer Grauer, Ruhr-Universität Bochum (Germany)

**HPC Platform:** JUQUEEN of JSC - **Date published:** September 2014

**More: Direct Numerical Simulations of Impeller Driven Turbulence and Dynamo Action …**

## Numerical Simulation of Aircraft Engine Related Two-Phase Flows

Aircraft engines are equipped with airblast atomizers to assure the liquid fuel injection. During airblast atomization a thin liquid film is passed by coflowing air streams, leading to the disintegration of the liquid sheet. The breakup process is still not well understood, especially a detailed insight into the phenomena of primary breakup is a major limitation in understanding these flow systems.

**Principal Investigator:** Benjamin Sauer, Technische Universität Darmstadt (Germany)

**HPC Platform:** SuperMUC of LRZ - **Date published:** September 2014

**More: Numerical Simulation of Aircraft Engine Related Two-Phase Flows …**

## Numerical Computation of Combustion Generated Noise with Direct Numerical Simulation

Scientists of a group of different institutions try to analyse in-depth the formation mechanism of noise generated from turbulent flames and to predict such noise radiations already during the development phase. HPC supercomputing resources serve as simulation platform for this project.

**Principal Investigator:** Feichi Zhang, Karlsruhe Institute of Technology (Germany)

**HPC Platform:** Hermit of HLRS - **Date published:** June 2014

**More: Numerical Computation of Combustion Generated Noise with Direct Numerical Simulation …**

## Comparison of Navier-Stokes-Fourier Equation and Grad's Moment Equation Solutions for Turbulence

Leveraging the computing power of GCS supercomputer JUQUEEN, scientists work on taking a first significant step towards the evaluation of extended gasdynamic models, such as e.g. the Grad 13 and the regularized Grad 13 equations, for the simulation and modeling of turbulent fluid motion.

**Principal Investigator:** Gregor Gassner, Universität zu Köln (Germany)

**HPC Platform:** JUQUEEN of JSC - **Date published:** May 2014

**More: Comparison of Navier-Stokes-Fourier Equation and Grad's Moment Equation Solutions for Turbulence …**

## Prediction of Stability Limits of Combustion Chambers with Large Eddy Simulation (LES)

Using the HPC capabilities of HLRS Stuttgart, scientists of the Karlsruhe Institute of Technology applied a physical model to predict the resonance characteristics of real, damped combustion systems. The model is able to describe the resonant characteristics of a single Helmholtz resonator type combustor for different operation conditions and geometries.

**Principal Investigator: **Franco Magagnato, Karlsruhe Institute of Technology (Germany)

**HPC Platform:** Hermit of HLRS - **Date published:** May 2014

**More: Prediction of Stability Limits of Combustion Chambers with Large Eddy Simulation (LES) …**

## PAdDLES: p-Adaptive Discretisations for Large Eddy Simulation in Industrial Geometry

Using the HPC capabilities of GCS, scientists assess a DGM (discontinuous Galerkin method) solver for scale-resolving simulations. The main goal of the solver is the evaluation of whether p-adaptive DGM can be used for fast and reliable LES of turbomachinery flows.

**Principal Investigator:** Koen Hillewaert, Cenaero (Belgium)

**HPC Platform:** JUQUEEN of JSC - **Date published:** April 2014

**More: PAdDLES: p-Adaptive Discretisations for Large Eddy Simulation in Industrial Geometry …**

## Transitions in Turbulent Rotating Thermal Convection

Scientists investigate the influence of temperature-dependent fluid properties (non-Oberbeck-Boussinesq effects) and rotation through direct numerical simulations for various fluids and a wide range of rotation rates to get closer to the understanding of realistic flows in nature and in engineering.

**Principal Investigator: ** Olga Shishkina, German Aerospace Center, Göttingen (Germany)

**HPC Platform:** SuperMUC of LRZ - **Date published:** March 2014

**More: Transitions in Turbulent Rotating Thermal Convection …**

## Simulation of the Unsteady Flow Around the Stratospheric Observatory For Infrared Astronomy (SOFIA)

To further improve the pointing stability and observation quality of the IR-telescope of an airborne stratospheric observatory, researchers investigate passive flow control methods by means of computational fluid dynamics simulations on HPC system SuperMUC of the LRZ Garching.

**Principal Investigator: ** Christian Engfer, DSI/IAG/Universität Stuttgart (Germany)

**HPC Platform:** SuperMUC of LRZ - **Date published:** February 2014

**More: Simulation of the Unsteady Flow Around the Stratospheric Observatory For Infrared Astronomy (SOFIA) …**

## Project HRPIPE, Direct Numerical Simulation of Pipe Flow at High Reynolds Numbers

Researchers from the Delft University of Technology used HLRS supercomputer Hermit to study turbulent pipe flow, which is--from an engineering point of view--one of the most important flow geometries because of its wide range of technical applications.

**Principal Investigator:** Bendiks Jan Boersma, Delft University of Technology (The Netherlands)

**HPC Platform:** Hermit of HLRS - **Date published:** March 2014

**More: Project HRPIPE, Direct Numerical Simulation of Pipe Flow at High Reynolds Numbers …**

## Direct Numerical Simulation of the Boundary Layers Transition and Interaction at the Entrance of a Plane Channel

Understanding the mechanisms involved in the turbulent transition in boundary layers is crucial for many engineering domains. The instabilities that develop in to those flows are highly non-linear and unsteady. Scientists used GCS supercomputers to study the turbulent transition of the boundary layers developing at the entrance of a plane channel.

**Principal Investigator: **Marc Buffat, Université Claude Bernard Lyon 1 (France)

**HPC Platform: **JUQUEEN (JSC), SuperMUC (LRZ) - **Date pub.:** Feb. 2014

**More: Direct Numerical Simulation of the Boundary Layers Transition and Interaction at the Entrance of a Plane Channel …**

## Numerical Simulations of a Supersonic Jet at High Reynolds Number with Turbulent Inflow Conditions

In a GCS Large Scale project, numerical simulations of a supersonic jet were performed on HPC system SuperMUC of LRZ, focusing on the research of the acoustic field.

**Principal Investigator:** Jörn Sesterhenn, TU Berlin (Germany)

**HPC Platform:** SuperMUC of LRZ - **Date published:** Feb. 2014

**More: Numerical Simulations of a Supersonic Jet at High Reynolds Number with Turbulent Inflow Conditions …**

## Fathoming the Processes Inside Rocket Combustion Chambers

Researchers at the Institute of Combustion Technology for Aerospace Engineering (IVLR) at the University of Stuttgart use petascale system Hermit of HLRS for very detailed, three-dimensional simulations to realistically reproduce the essential processes in rocket combustion chambers like mixing of fuel and air, ignition and flame stabilization at supersonic conditions.

**Principal Investigator:** Peter Gerlinger, Universität Stuttgart (Germany)

**HPC Platform:** Hermit of HLRS - **Date published:** January 2014

**More: Fathoming the Processes Inside Rocket Combustion Chambers …**

## Aircraft Wake Vortex Evolution During Approach and Landing With and Without Plate Lines

Computational fluid dynamics simulations executed on GCS system SuperMUC of LRZ Garching are used to investigate the complex vortex system detaching from the aircraft wings in high-lift configuration.

**Principal Investigator: **Frank Holzäpfel, German Aerospace Center (DLR), Weßling (Germany)

**HPC Platform:** SuperMUC of LRZ - ** Date published:** January 2014

**More: Aircraft Wake Vortex Evolution During Approach and Landing With and Without Plate Lines …**

## Hypersonic Boundary-Layer Transition

A team of scientists from the Institute of Aerodynamics and Gas Dynamics of University of Stuttgart are performing direct numerical simulations and sophisticated stability analyses with regard to the so-called hypersonic flight, i.e.with the goal to be able to accelerate an aircraft to at least about five times the speed of sound.

**Principal Investigator:** Markus J. Kloker, IAG, Universität Stuttgart (Germany)

**HPC Platform: **Hermit of HLRS - **Date published:** Sept. 2013

**More: Hypersonic Boundary-Layer Transition …**

## Li-Ion Batteries in Hybrid and Pure Electric Vehicles

Project ‘Development and Validation of Thermal Simulation Models for Li-Ion Batteries in Hybrid and Pure Electric Vehicles’ (asc(s, Battery Design, CD-adapco, Daimler AG, Opel AG and Porsche AG) concentrates on the development of a simulation environment for the electro-thermal layout of a lithium ion battery module in a vehicle. The project team pursues the development of optimized design concepts for electrified vehicles to fulfill increasing demands on energy consumption, driving range, and durability.

**Principal Investigator:** Jenny Kremser, ASC-S Stuttgart (Germany)

**HPC Platform:** Hermit of HLRS - **Date published: **Sept. 2013

**More: Li-Ion Batteries in Hybrid and Pure Electric Vehicles …**

## Laminar-Turbulent Transition in Aerodynamics Boundary Layers

Laminar Turbulent Transition in Aerodynamics Boundary Layers: Scientists from the Institute of Aerodynamics and Gas Dynamics of University Stuttgart are doing simulations on GCS supercomputers to achieve a comprehensive understanding of three-dimensional dynamic instability processes, which is a pre-requisite for successful Laminar Flow Control (LFC).

**Principal Investigator:** Ewald Krämer, IAG/Universität Stuttgart (Germany)

**HPC Platform:** Hermit of HLRS - **Date published:** Sept. 2013

**More: Laminar-Turbulent Transition in Aerodynamics Boundary Layers …**

## Direct Numerical Simulation of the Flow in an Internal Combustion Engine

To increase the efficiency and reduce the pollutant emissions of combustion engines, researchers simulate the complex flow field in internal combustion engines which has significant influence on the formation of the fuel-air-mixture in the combustion chamber and on the combustion process itself.

**Principal Investigator:** Claudia Günther, AIA/RWTH Aachen (Germany)

**HPC Platform:** Hermit of HLRS - **Date published:** Sept. 2013

**More: Direct Numerical Simulation of the Flow in an Internal Combustion Engine …**

## Numerical Investigation of the Flow Field Around Delta Wings

Delta wings, or wings with a triangular planform, are an important reference configuration for applied high-performance aerodynamics as well as for basic fluid mechanics studies.

**Principal Investigator:** Stefan Hickel, LES Group, TU München (Germany)

**HPC Platform:** SuperMUC of LRZ - **Date published:** Sept. 2013

**More: Numerical Investigation of the Flow Field Around Delta Wings …**

## Project FENFLOSS

Today, hydropower is the most important and widely used renewable energy source. Due to the strong increase of fluctuating renewable energies, a great amount of regulating power is necessary in the net, which is mainly available from hydropower. As a consequence, the hydraulic turbines are very often operated in extreme off-design conditions.

**Principal Investigator:** Albert Ruprecht, Universität Stuttgart (Germany)

**HPC Platform:** Hermit of HLRS - **Date published:** Sept. 2013

**More: Project FENFLOSS …**

## Ablation Process of Femto Second Laser Pulses

Laser ablation is a technology which gains increasingly more importance for drilling, welding, structuring and marking of all kind of materials. Molecular dynamics simulations contribute to new insight into the not completely comprehended ablation process with the short femto second laser pulses.

**Principal Investigator:** Johannes Roth, Universität Stuttgart (Germany)

**HPC Platform:** Hermit of HLRS - **Date published: **Sept. 2013

**More: Ablation Process of Femto Second Laser Pulses …**