# Latest Projects (Overview)

Find out about the latest simulation projects run on the GCS supercomputers. For the complete overview of projects, sorted by research fields, please choose from the list in the left column.

## Direct Numerical Simulation of Turbulent Heat Transfer with a Supercritical Fluid

In the quest for efficiency enhancement in energy conversion, supercritical carbon dioxide (sCO2) is an attractive alternative working fluid. However, the heat transfer to sCO2 is much different in the supercritical region than the subcritical region due to the strong variation of thermophysical properties which bring the effects of flow acceleration and buoyancy. The peculiarity in heat transfer and flow characteristics cannot be predicted accurately by using conventional correlations or Reynolds-Averaged Naiver-Stokes (RANS) simulations based on the turbulence models. Therefore, direct numerical simulation (DNS) is used in this ongoing project. In DNS, the Naiver-Stokes equations are numerically solved without any turbulence models. For this accurate and reliable approach, one needs to resolve very fine spatial and temporal scales, which ultimately results in the requirement of high-performance computing.

**Principal Investigator:** Eckart Laurien, Institute of Nuclear Energy and Energy Systems (IKE), University of Stuttgart (Germany)

**HPC Platform:** Hazel Hen (HLRS) -** Date published: **May 2018* (DNSTHTS)*

**More: Direct Numerical Simulation of Turbulent Heat Transfer with a Supercritical Fluid …**

## Petascale Computations for Atomic and Molecular Collisions: PAMOP and PAMOP2

An international group of scientists leverages high-performance computing to support current and future measurements of atomic photoionization cross-sections at various synchrotron radiation facilities, ion-atom collision experiments, together with plasma, fusion and astrophysical applications. In their work they solve the Schrödinger or Dirac equation using the *R-*matrix or *R-*matrix with pseudo-states approach from first principles. Cross-sections and rates for radiative charge transfer, radiative association, and photodissociation collision processes between atoms and ions of interest for several astrophysical applications are presented.

**Principal Investigator: **Alfred Müller, Institut für Atom- und Molekülphysik, Universität Giessen (Germany)

**HPC Platform:** Hazel Hen/HLRS - **Date published:** May 2018 *(PAMOP/PAMOP2)*

**More: Petascale Computations for Atomic and Molecular Collisions: PAMOP and PAMOP2 …**

## Simulating the Universe: Predictive Galaxy Formation towards the Smallest Scales

Modern simulations of galaxy formation, which simultaneously follow the co-evolution of dark matter, cosmic gas, stars, and supermassive black holes, enable us to directly calculate the observable signatures that arise from the complex process of cosmic structure formation. TNG50 is an unprecedented ‘next generation’ cosmological, magneto-hydrodynamical simulation -- the third and final volume of the IllustrisTNG project. It captures spatial scales as small as ~100 parsecs, resolving the interior structure of galaxies, and incorporates a comprehensive model for galaxy formation physics.

**Principal Investigator: **Dylan Nelson, MPA Garching, and Annalisa Pillepich, MPIA Heidelberg (Germany)

**HPC Platform:** Hazel Hen/HLRS - **Date published:** May 2018 *(GCS-dwar)*

**More: Simulating the Universe: Predictive Galaxy Formation towards the Smallest Scales …**

## Multiscale Simulations of Fluid-Structure-Acoustic Interaction

This project was part of the ExaFSA project that investigates the possibility to exploit high-performance computing systems for integrated simulations of all parts contributing to noise generation in flows around obstacles. Such computations are challenging, as they involve the interaction of various physical effects on different scales. In this context, the compute time on SuperMUC granted for this project was used to particularly investigate the coupling of the flow within a large acoustic domain with individual discretization methods.

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

**HPC Platform:** SuperMUC (LRZ) -** Date published: **April 2018* (pr84xu)*

**More: Multiscale Simulations of Fluid-Structure-Acoustic Interaction …**

## The Emergence of Structures in the Next Generation of Hydrodynamical Cosmological Simulations

Hydrodynamical simulations of galaxy formation have now reached sufficient physical fidelity to allow detailed predictions for their formation and evolution over cosmic time. The aim of this project is to carry out a new generation of structure formation simulations, IllustrisTNG, that reach sufficient volume to make accurate predictions for clustering on cosmologically relevant scales, while at the same time being able to compute detailed galaxy morphologies, the enrichment of diffuse gas with metals, and the amplification of magnetic fields during structure growth.

**Principal Investigator: **Volker Springel, Heidelberg Institute for Theoretical Studies, Heidelberg University, and Max-Planck Institute for Astrophysics (Germany)

**HPC Platform:** Hazel Hen/HLRS - **Date published:** April 2018 *(GCS-ILLU)*

**More: The Emergence of Structures in the Next Generation of Hydrodynamical Cosmological Simulations …**

## Thermodynamics with Overlap Fermions

The Universe soon after the Big Bang was hot and full of massless particles, so called fermions and bosons. As it expanded and cooled down particles become massive. They acquired mass from several kinds of mechanisms, which are investigated in detail in heavy-ion collision experiments, and also in theory. Ab-initio theoretical calculations require simulating massless particles on a supercomputer. This is a difficult problem, fortunately with an existing solution, the so-called overlap discretization of fermions. Here we make simulations with overlap fermions using supercomputing power.

**Principal Investigator:** Balint Toth, Bergische Universität Wuppertal (Germany)

**HPC Platform:** JUQUEEN (JSC) - **Date published: **April 2018 *(hwu26)*

**More: Thermodynamics with Overlap Fermions …**

## Exploring the QCD Phase Diagram Using the Complex Langevin Equation

The simulation of nuclear matter at nonzero baryon density presents a notoriously hard problem in lattice QCD. The usual simulation strategies depend on the exploration of the configuration space by interpreting the weight of each configuration in an average as a probability, which is however not valid here as the weight is non positive. This is called the ‘sign problem’ of nonzero density QCD. In this project, the researchers use a method based on the Complex Langevin equation evading the sign problem to map out the phase diagram of nuclear matter.

**Principal Investigator:** Dénes Sexty, Bergische Universität Wuppertal (Germany)

**HPC Platform:** JUQUEEN (JSC) - **Date published: **March 2018 *(hwu22)*

**More: Exploring the QCD Phase Diagram Using the Complex Langevin Equation …**

## Hadronic Corrections to the Muon Anomalous Magnetic Moment

Supercomputing resources are used to investigate a long standing discrepancy between theoretical calculation and experiment in the case of an elementary particle called muon. This muon magnetic moment puzzle is considered by many as a smoking gun for new physics, ie. something that cannot t into the current framework of particle physics.

**Principal Investigator:** Kálmán Szabó, Forschungszentrum Jülich GmbH (Germany)

**HPC Platform:** JUQUEEN (JSC) - **Date published: **March 2018 *(hfz00)*

**More: Hadronic Corrections to the Muon Anomalous Magnetic Moment …**

## Numerical Investigation of Convective Patterns in the Solar Near-Surface Shear Layer

The characteristic patterns seen on the solar surface, on gas giants, in Earth's atmosphere and oceans, and many other geo- and astrophysical settings originate from turbulent convection dynamics flows driven by a density difference caused by, for instance, a temperature gradient. Convection in itself is inherently complex, but often it is the interaction with other forces, such as the Coriolis and Lorentz force due to rotation and magnetic fields, that determines the actual shape and behaviour of the flow structures. Understanding these convective patterns is often essentially tantamount to understanding the underlying physics at play. In this project, surveys through the huge parameter space are conducted, to not only categorise flow morphologies, but also to derive theoretical relations, in particular, for the heat and momentum transport.

**Principal Investigator:** Olga Shishkina, Max Planck Institute for Dynamics and Self-Organization, Göttingen (Germany)

**HPC Platform:** SuperMUC (LRZ) - **Date published:** March 2018* **(pr94na)*

**More: Numerical Investigation of Convective Patterns in the Solar Near-Surface Shear Layer …**

## Model Development for Fluid Flow Applications

The dynamic behaviour of fluid motion is driven by processes on a wide range of spatial and temporal scales. In a project run by Heidelberg University scientists, parts of model systems that describe fluid dynamics and temperature evolution were investigated. The models are formulated in terms of velocity, temperature, pressure, and density. The researchers employ a hierarchy of different physical models with an increasing degree of complexity. Additionally, uncertain input parameters are taken into account.

**Principal Investigator:** Philipp Gerstner, Engineering Mathematics and Computing Lab (EMCL), Ruprecht-Karls-Universität Heidelberg (Germany)

**HPC Platform:** JUQUEEN (JSC) -** Date published: **March 2018* (hka14)*

**More: Model Development for Fluid Flow Applications …**

## Study of Strong Decays and Resonances at the Physical Pion Mass in Lattice QCD

In the quark model mesons are made up of a quark and an antiquark and baryons of three quarks. The theory of the strong interactions, QCD, however, suggests that more complicated structures are possible. New experimental results strongly point at the possibility of tetraquarks, close to strong decay thresholds into two mesons. To understand these structures, simulations are necessary that include these scattering states. For the first time such as study was performed in Lattice QCD, with nearly physical quark masses. First the well-known ρ-resonance was investigated and then the Tetraquark candidate states D*_{s0}(2317) and D_{s1}(2460).

**Principal Investigator:** Gunnar Bali, Institut für Theoretische Physik, Universität Regensburg (Germany)

**HPC Platform:** SuperMUC (LRZ) - **Date published: **March 2018 *(pr94ni)*

**More: Study of Strong Decays and Resonances at the Physical Pion Mass in Lattice QCD …**

## Investigation of Green Propellants in Rocket Combustion Chambers

Researchers at the Chair of Turbomachinery and Flight Propulsion (LTF) at the Technical University Munich numerically investigate flow and combustion in rocket engines using “green” propellants. The current focus involves researching methane/oxygen as a propellant combination, promising to be a good replacement for the commonly used hydrazine, offering good performance, storability, and handling qualities, while also being significantly less toxic. The goal of the project is an improved understanding of the relevant physical processes and a reliable prediction of thermal loads on the combustor.

**Principal Investigator:** Prof. Dr.- Ing. Oskar J. Haidn, TUM Department of Mechanical Engineering, Technical University of Munich (Germany)

**HPC Platform:** SuperMUC (LRZ) -** Date published: **March 2018* (pr83bi)*

**More: Investigation of Green Propellants in Rocket Combustion Chambers …**

## Theoretical Heterogeneous Catalysis from Advanced Ab Initio Molecular Dynamics Simulations

The work horse of chemical industry is heterogeneous catalysis meaning that complex solid materials (catalysts) are used to facilitate chemical reactions, thus reducing production costs. To improve such catalysts in a systematic manner, knowledge of the ongoing reactions is most desirable. One of the key reactions industry performs at large scales is methanol (“wood alcohol”, H_{3}COH) synthesis from syngas being a mixture of gaseous CO_{2}, CO, and H_{2}. Scientists investigated the methanol production which is catalyzed using copper nanoparticles on a zinc oxide support. Based on sophisticated molecular dynamics sampling techniques in conjunction with the large-scale parallel platform SuperMUC at LRZ, they discovered a hitherto unknown complex reaction network with many parallel paths as well as dead ends that ultimately leads to the reaction of syngas to methanol.

**Principal Investigator:** Dominik Marx, Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, Bochum (Germany)

**HPC Platform:** SuperMUC (LRZ) - **Date published:** March 2018* **(pr63ce)*

**More: Theoretical Heterogeneous Catalysis from Advanced Ab Initio Molecular Dynamics Simulations …**

## Hadron Scattering and Resonance Properties from Lattice QCD

It is a long lasting dream in nuclear physics to study nuclei like, for instance, carbon directly from Quantum Chromodynamics (QCD), the underlying fundamental theory of strong interactions. Such an endeavor is very challenging both, methodically and numerically. Towards this goal physicists from the European Twisted Mass Collaboration and in particular the University of Bonn have started to investigate two hadron systems using the approach of Lattice QCD.

**Principal Investigator:** Carsten Urbach, Helmholtz Institut für Strahlen und Kernphysik (Theorie), Rheinische Friedrich-Wilhelms-Universität Bonn (Germany)

**HPC Platform:** JUQUEEN/JSC and Hazel Hen/HLRS

**Date published: **February 2018 *(hbn28/GCS_hsrp)*

**More: Hadron Scattering and Resonance Properties from Lattice QCD …**

## 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. Applications of this regime reach from deep solar convection, via convection in the liquid metal core of the Earth to liquid metal batteries for grid energy storage and nuclear engineering technology. Laboratory experiments in low-Prandtl-number convection for Pr < 0.1 have to be conducted in liquid metals which are inaccessible for laser imaging techniques and require analysis by ultrasound or X-rays. Direct numerical simulations of this regime of turbulent convection at high Rayleigh numbers are the only way to reveal the full three-dimensional structure of temperature and velocity fields.

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

**HPC Platform:** JUQUEEN (JSC) -** Date published: **February 2018* (hil09)*

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

## Fathoming the Processes inside Rocket Combustion Chambers

At the Institute of Combustion Technology for Aerospace Engineering (IVLR) of the University of Stuttgart a team of scientists numerically investigates reacting flows at conditions typical for modern space transportation systems. The goal of the project is the better understanding of the ongoing processes in the combustion chambers and an improvement of the thermal load predictions. The research is integrated into the program "Technological Foundations for the Design of Thermally and Mechanically Highly Loaded Components of Future Space Transportation Systems" funded by the DFG.

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

**HPC Platform:** Hazel Hen (HLRS) -** Date published: **February 2018* (scrcomb)*

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

## Numerical Analysis of Space Launcher Wake Flows

A research group from the Institute of Aerodynamics (AIA) of the RWTH Aachen University utilized the computing power of Hazel Hen for large-scale simulations to analyze the intricate wake flow phenomena of space launchers. The objective of the project is the fundamental understanding of the origin of so called buffet loads acting on the nozzle which can lead to critical structural damage and to develop flow control devices to increase the efficiency and reliability of orbital transportation systems necessary for the steadily increasing demand for communication and navigation satellites.

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

**HPC Platform:** Hazel Hen (HLRS) -** Date published: **February 2018* (gcs_jean)*

**More: Numerical Analysis of Space Launcher Wake Flows …**

## Influence of Velocity Changes During Directional Solidification Using Large-Scale Phase-Field Simulations

Simulations have long been an integral part to supplement experiment and theory and became a powerful method to improve the understanding of physical phenomena. Leveraging the phase-field method - an established means for the investigation of the diffusion and phase-transformation-included microstructure evolution during solidification processes in 3D - materials scientists use high-performance computing to study representative volume elements resolving the multiphase microstructure which can be compared with experimental micrographs. Massive-parallel and highly optimized solvers are applied to increase the efficiencies of the simulations in the scientists' pursuit to investigate the directional solidification of binary and ternary eutectic reactions in large-scale domains.

**Principal Investigator:** Britta Nestler, Karlsruhe Institute of Technology, Karlsruhe (Germany)

**HPC Platform:** Hazel Hen (HLRS) - **Date published:** February 2018** ***(pace3d)*

**More: Influence of Velocity Changes During Directional Solidification Using Large-Scale Phase-Field Simulations …**

## Improved Characterization of Fluxes Across Compartmental Interfaces

Data Assimilation is an integral tool to enable precise forecasts and becomes increasingly important to derive the values of uncertain parameters due to lack of observations. Numerical models of Earth system compartments are coupled in order to simulate physically consistent water and energy fluxes in the subsurface-landsurface-atmosphere system. Such model systems become increasingly important to analyze and understand the complex processes at boundaries of terrestrial compartments and interdependencies of states across these boundaries. As such, data assimilation for these coupled systems needs to be developed.

**Principal Investigator:** Clemens Simmer, Meteorological Institute, University of Bonn (Germany)

**HPC Platform:** JUQUEEN/JURECA (JSC) - **Date published:** February 2018* (hbn29)*

**More: Improved Characterization of Fluxes Across Compartmental Interfaces …**

## Unravelling the interior Evolution of Rocky Planets Through Large-Scale Numerical Simulations

The large amount of data returned by several space missions to the terrestrial planets has greatly improved our understanding of the similarities and differences between the innermost planets of our Solar System. Nevertheless, their interior remains poorly known since most of the data is related to surface processes. In the absence of direct data of the interior evolution of terrestrial planets, numerical simulations of mantle convection are an important mean to reconstruct the thermal and chemical history of the interior of the Earth, Moon, Mercury, Venus and Mars. In this project, run on Hornet of HLRS, researchers used the mantle convection code Gaia to model the thermal evolution of terrestrial planets and in particular the early stage of their history.

**Principal Investigator: **Ana-Catalina Plesa, German Aerospace Center/DLR, Berlin (Germany)

**HPC Platform:** Hornet/HLRS - **Date published:** January 2018* (MATHECO)*

**More: Unravelling the interior Evolution of Rocky Planets Through Large-Scale Numerical Simulations …**

## Direct Numerical Simulation of the Formation of Subaqueous Sediment Patterns: Evolution Beyond the Initial Formation

This project has investigated the problem of sediment transport and subaqueous pattern formation by means of high-fidelity direct numerical simulations which resolve all the relevant scales of the flow and the sediment bed. In order to realistically capture the phenomenon, sufficiently large computational domains with up to several billion grid nodes are adopted, while the sediment bed is represented by up to a million mobile spherical particles. The numerical method employed features an immersed boundary technique for the treatment of the moving fluid-solid interfaces and a soft-sphere model to realistically treat the inter-particle contacts. The study provides, first and foremost, a unique set of spatially and temporally resolved information on the flow field and the motion of individual particles which make up the sediment bed. Furthermore, based on the rigorous analysis of the generated data, the fluid flow and particle motion over the evolving patterns are studied in great detail, providing novel insight into the different mechanisms involved in the processes of sediment pattern formation.

**Principal Investigators:** Aman G. Kidanemariam and Markus Uhlmann, Computational Fluid Dynamics group, Institute for Hydrodynamics, Karlsruhe Institute of Technology (KIT), Germany

**HPC Platform:** SuperMUC (LRZ) - **Date published:** January 2018** ***(pr84du)*

**More: Direct Numerical Simulation of the Formation of Subaqueous Sediment Patterns: Evolution Beyond the Initial Formation …**

## Unravelling the Gating Process of a Complex Ion Channel

Ion channels play a fundamental role in maintaining vital electrochemical gradients across the cell membrane and in enabling electrical signaling across cells. Key characteristics of ion channel function that can be experimentally quantified include ion permeation rates and selectivities. In this project, the functional mechanism of a very important class of ion channels is investigated with the help of molecular dynamics simulations. The computer simulations exhibit a wide range of GLIC states from completely closed to wide open, with conductance and selectivity for the open state in agreement with experimental values. The scientists are now beginning to investigate the intricate opening/closing mechanism in detail to ultimately explain it from a physics perspective.

**Principal Investigator:** Helmut Grubmüller, Max-Planck-Institute for Biophysical Chemistry, Göttingen (Germany)

**HPC Platform:** SuperMUC (LRZ) - **Date published:** January 2018 *(pr48pa)*

**More: Unravelling the Gating Process of a Complex Ion Channel …**

## Influence of Hydrogen Bonds on Surface Reactions

Researchers at the University of Paderborn currently focus on the further development of the ring polymer path integral molecular dynamics method, and in particular on the simulation of vibrational spectroscopy methods. Leveraging the petascale computing capabilities of HPC system JUQUEEN, they have improved the current understanding of hydrogen bond cooperation by using a proper basis for its description, namely its energy.

**Principal Investigator:** Thomas Kühne, Department of Chemistry, University of Paderborn (Germany)

**HPC Platform:** JUQUEEN (JSC) - **Date published:** January 2018* **(hpb01)*

**More: Influence of Hydrogen Bonds on Surface Reactions …**

## The Conformal Window and Technicolour Theories with Adjoint Fermions

In this project, a multi-instutional team of researchers investigated new strongly interacting theories beyond the Standard Model of particle physics. These theories share fascinating but still puzzling features with the strong interaction of nuclear forces. In addition, they offer new phenomena and exotic properties that make them interesting for a more general understanding of the foundations of particle physics.

**Principal Investigator:** Georg Bergner, Theoretisch-Physikalisches Institut, Universität Jena (Germany)

**HPC Platform:** JUQUEEN/JURECA (JSC) - **Date published: **January 2018 *(hwu08)*

**More: The Conformal Window and Technicolour Theories with Adjoint Fermions …**

## Direct Numerical Simulation of Fully-Rough Open-Channel Flow Over Spherical Roughness Elements

Open channel flow can be considered as a convenient "laboratory" for investigating the physics of the flow in rivers. One open questions in this field is related to the influence of a rough boundary (i.e. the sediment bed) upon the hydraulic properties, which to date is still unsatisfactorily modelled by common engineering-type formulae. The present project aims to provide the basis for enhanced models by generating high-fidelity data of shallow flow over a bed roughened with spherical elements in the fully rough regime. In particular, the influence of the roughness Reynolds number and of the spatial roughness arrangement upon the turbulent channel flow structure is being studied.

**Principal Investigators:** Markus Uhlmann, Karlsruhe Institute of Technology/KIT (Germany) and Marco Mazzuoli, University of Genoa (Italy)

**HPC Platform:** SuperMUC (LRZ) - **Date published:** January 2018** ***(pr87yo)*

**More: Direct Numerical Simulation of Fully-Rough Open-Channel Flow Over Spherical Roughness Elements …**

## Simulation of Turbulent Flow Around a Wing

This project aims at the simulation of the influence of a turbulent atmospheric boundary layer flow on a wing. For this purpose the compressible flow solver DLR-TAU is used, which is developed by the German Aerospace Center (DLR). For initialising the simulation with a turbulent wind field a method to generate synthetic turbulence is used. This method uses statistics from measured time series from the atmospheric boundary layer to generate a threedimensional turbulent wind field which can be used as initial field in the flow simulations.

**Principal Investigators:** Torsten Auerswald and Jens Bange, Center for Applied Geoscience, University of Tübingen (Germany)

**HPC Platform:** Hermit/Hornet (HLRS) -** Date published: **January 2018* (WAF)*

**More: Simulation of Turbulent Flow Around a Wing …**

## Direct Numerical Simulation of Turbulent Mixing in the Planetary Boundary Layer

The planetary boundary layer (PBL) is the lower layer of the troposphere, the layer that directly feels surface effects on time scales smaller than a day. Planetary boundary layers are important in climatology—modulating the fluxes between atmosphere, land and ocean—, and in meteorology—influencing weather conditions—, but key properties remain poorly understood, largely because the PBL is turbulent, and understanding and characterizing the multi-scale nature of turbulence remains challenging. High-performance computing and direct numerical simulations are decisively contributing to advance our understanding of PBL properties.

**Principal Investigator:** Juan Pedro Mellado, Max Planck Institute for Meteorology, Hamburg (Germany)

**HPC Platform:** JUQUEEN of JSC - **Date published:** December 2017

**More: Direct Numerical Simulation of Turbulent Mixing in the Planetary Boundary Layer …**