LATEST RESEARCH RESULTS

Turbulence is a ubiquitous phenomenon that affects everything ranging from blood flow in our arteries, via aircraft to processes that form stars such as our Sun. In particular, turbulence that moves faster than the speed of sound, so-called supersonic turbulence, is important in many astrophysical settings, for example in giant molecular clouds that are the birth places of stars and that are scattered throughout galaxies. However, many properties of supersonic turbulence are poorly understood.

Fluids are key agents in many geological processes of the Earth's crust and upper mantle. Despite their importance for geological and technological processes, their thermodynamic and physical properties are not well constrained at many of the relevant conditions, especially in the supercritical state. In this project, we collaborate with experimentalists and thermodynamicists to study properties of hydrothermal fluids in a wide range of densities and temperatures. The main goals of the simulations are the development of molecular structure models including electronic and vibrational properties and prediction of thermodynamic properties such as solute dissociation constants and partial molar volumes.

The air stream in a gas turbine is firstly compressed and delivered to the combustion chamber, where fuel is mixing in and burnt, releasing a tremendous amount of heat. The hot turbulent bumt gases expand through the turbine placed downstream and the exhaust nozzle. Over the last decades, the turbine inlet temperature has increased because this leads to a higher efficiency of the gas turbine. The temperature of the hot gas of the combustion chamber (2,200 °C) and turbine section (1,700 °C) surpasses the material's maximum temperature limit (900 °C). In order to safeguard the metal walls from damage, they are covered by a ceramic thermal barrier coating (TBC) but this is not sufficient to protect the metal components from overheating.

Experimental advancements within the last two decades have enabled unprecedented control of quantum systems, posing outstanding challenges for their theoretical description. Our project is based on a novel computational strategy at the intersection of machine learning and quantum physics, utilizing artificial neural networks to efficiently represent quantum wave functions. By leveraging supercomputing resources from FZ Jülich and the Gauss Centre for Supercomputing, we have advanced the theoretical understanding of strongly interacting systems in two dimensions, including the first demonstration of the quantum Kibble-Zurek mechanism.

This project targets various central questions in modern astrophysics, including "What is the nature of dark matter?", "How do galaxies form and evolve?" and "Do we understand the extremes of the universe?". Dwarf galaxies provide a natural laboratory for confronting these questions as we will explain below. The formation of dwarf galaxies tracks an extreme situation in various ways. Dwarf galaxies are assumed to be the very first type of galaxy to form in the earliest Universe.

The aim of this project is to create a highly accurate cosmological, hydrodynamical simulation model that can produce extremely realistic representations of dwarf galaxies right into the centers, where dark matter models can be tested.

The IHPms21 project combined advanced computer simulations with experimental techniques to develop new materials for future microelectronics that are compatible with silicon technology. Using ab initio density functional calculations, the project helped interpret experimental results and guide further research. The team achieved three key outcomes: first, they explained why germanium surfaces behave differently depending on their orientation during graphene growth; second, they uncovered how multilayer hexagonal boron nitride (hBN) can grow from an inert gas, despite its chemical inactivity; and third, they analyzed photoemission spectra to reveal the presence of ultrathin β-Ga₂O₃ films on the surface of ZnGa₄O₄ crystals.

Liquid metals like Gallium (Ga) are a promising platform for catalytic devices such as SCALMS (Supported Catalytically Active Liquid Metal Solutions). Ga develops an oxidized surface layer (Ga₂O₃), which is known to have a major impact on droplet dynamics and technological performance.

We simulate droplets via a coupled Immersed Boundary Lattice-Boltzmann (IBLB) method, for which we introduce a generalized model for elastic properties of the membrane, to cover properties of oxidized droplets and beyond [1].

Membrane topology transformations – such as scission, fusion, and pore formation – are driven by membrane tension, curvature stress, and lipid dynamics, playing critical roles in exocytosis and organelle division. The final stage of cellular compartment division involves the scission of a highly constricted membrane neck. Using self-consistent field theory (SCFT), we explore the mechanisms of scission in single- and double-membrane neck structures.

The Earth is a dynamic system, various physical processes lead to deformations of the Earths surface or mass transport in its interior. Quantifying the changes with the help of measurements is a key task of geodesy, for instance to make signals attributed to climate change visible. For this, reference systems and reference surfaces are required. E.g. sea level rise refers to the so called Mean Sea Surface (MSS), or the geoid as an equipotential surface is required to show mass transport. The reference surfaces can be determined from hundreds of million measurements collected by satellites. Due to the characteristics of the collected data and the complexity of the surfaces, high performance computing is required for the numerical analysis

In July 2021, a devastating flood hit Central and Western Europe, causing severe damage, especially in the Ahr region in Germany. Researchers at the University of Bonn investigated the role of soil moisture in intensifying this extreme event. Using the JUWELS supercomputer at Forschungszentrum Jülich, they simulated varying soil moisture conditions to assess its impact on precipitation. The findings suggest that land surfaces contributed significantly to the heavy rainfall, with potential for even more precipitation under wetter soil moisture conditions. These insights can help to improve understanding of land-atmosphere interactions and disentangle drivers of extreme events.

Irradiation modeling is a crucial aspect of integrated photovoltaic (PV) system yield prediction and optimizations of the design and dimensions of PV systems. Shading models typically rely on high-resolution topography data that includes buildings and vegetation. However, the cost and limited availability of such data pose significant challenges. In this project, we took an innovative approach by considering an alternative source of topography data: maps. Specifically, we focused on the OpenStreetMap (OSM) due to its open-data availability. While maps cannot be directly used for irradiance modeling, we explored novel approaches to overcome this challenge.

Bulk metallic glasses (BMGs) are known to have remarkable mechanical properties, such as high tensile strength, elasticity, and yield strength, which surpass those of many crystalline and polycrystalline metals. These properties make BMGs highly promising candidates for applications requiring materials that can withstand high and complex mechanical stress. However, BMGs have drawbacks; they show strain softening, resulting in localized deformation in the form of shear transformation zones that later lead to the formation of shear bands. This strain-softening characteristic limits their broader application potential, as it can lead to surface defects and, ultimately, fracture.

Prof. Dr. Holger Gohlke and Jesko Kaiser investigated the binding of resensitizers in the nicotinic acetylcholine receptor as a potential treatment option for nerve agent poisoning. They identified a potential allosteric binding site, explaining the experimentally observed effect on the receptor. Based on these results, the researchers identified novel analogs with improved properties and new lead structures with improved affinity compared to MB327, potentially acting as new starting points to ultimately close the gap in nerve agent poisoning treatment.

Chiral amines, a group of small chemicals, are central building blocks to a variety of fine chemical products. These include agrochemicals and pharmaceuticals such as Sitagliptin, a potent drug used to treat type II diabetes. Accordingly, biotech and pharmaceutical companies are highly interested in the efficient and sustainable production of these compounds. A group of enzymes already in use to fill this need are Transaminases (TAs). In this project, Prof. Dr. Gohlke and Steffen Docter investigated the thermal unfolding behavior of two sets of TA variants of fold type I and IV families of PLP-dependant enzymes by simulating rigid cluster decompositions using Constraint Network Analysis (CNA).

The efficiency of any opto-electronic device, such as a solar cell, light emitting diode, or photodetector, is intrinsically linked to the nature of the electronic quantum states of the photoactive material. For a deeper understanding and targeted development of new devices, an improved theoretical description of bound electronic excitations, i.e., excitons and trions, is crucial.

The exponential scaling in computational cost when simulating quantum many-body systems poses a significant challenge to their understanding. Variational methods, that approximate the state of the quantum system using an ansatz function, promise to lower that computational cost while making no approximations about the interactions that occur in the system. A novel type of ansatz function, which we explore thoroughly in this project, uses neural networks to approximate the state of the system. As is usual in deep learning, we rely heavily on the use of GPUs during execution, thereby making the use of the JUWELS Booster Module a necessity.

Researchers from Heinrich Heine University Düsseldorf have investigated the interaction of high-intensity laser pulses with matter using particle-in-cell simulations. Their research has led to a novel mechanism for compact ion acceleration, a method to generate spin-polarized ion beams, and a potential path to probe quantum electrodynamics.

We are all made of atoms, different types of atoms, and different combinations of them, which, by their turn, are composed of a cloud of electrons and a nucleus. A nucleus contains at least one proton in its simplest form, the hydrogen atom. Comprehending the proton, the origin of its measured properties, like its mass and electric charge, and its structure is, thus, one of the most important endeavors of the physical sciences. How can we probe/see the proton and its structure?

In a breakthrough that could revolutionize particle accelerators, scientists have discovered how to better control high-energy electron beams using ultra-powerful lasers. This new understanding delves deep into the complex dance between intense laser pulses and the plasma they create, revealing the subtle mechanisms that influence electron beam stability.

The mitigation of aircraft noise is a major goal of the society to reduce the harmful effects on the human health and cognitive performance when exposed to a pervasive noise level. Although several events in the past have temporarily reduced the air traffic, a long-term constant growing rate if 4- 8%p.a. of passengers has been observed in the recent years. New concepts for on-demand Urban Air Mobility evolve and thus, additionally implying an extension of urban areas. Coping with this trend, the ACARE 1 defined ambitious goals of Europe’s vision for aviation for the year 2050 in the Flightpath 2050.