Kompetenzplattform für Softwareeffizienz und Höchstleistungsrechnen

The recently developed wind gust generator, the adaptive nozzle (Wood and Breuer, 2025) , features a nozzle with a fully rotatable upper contour, enabling a smooth gust generation with low unwanted flow disturbances. While preserving the underlying gust-generation principle of its predecessor, the new design significantly reduces pressure losses caused by flow blockage and preserves the original horizontal trajectory of the flow along the streamwise direction. While experiments have validated the improved design, a comprehensive numerical analysis is crucial to resolve the three-dimensional flow fields across the entire computational domain. This shall also facilitate capturing the resulting transient aerodynamic loads on a wind tunnel specimen — quantities difficult to measure experimentally. To accurately capture the complex flow dynamics, high- fidelity large-eddy simulations are conducted, modeling the nozzle’s upper contour as a dynamic immersed boundary (IB). A curvilinear Eulerian grid is employed to ensure both efficient and precise spatial resolution of the problem. The moving least-squares (MLS) version of the direct forcing IB approach (Vanella and Balaras, 2009) is used to construct an IB kernel for each Lagrangian marker. Additionally, the MLS approach is also applied to construct one-sided kernel functions for Lagrangian points near the boundaries of the computational domain. Challenges related to the efficient IB simulation on curvilinear grids are addressed, and a solution is proposed within the MLS framework. The predicted results are analyzed in detail and validated against the experimental data by Wood and Breuer (2025) , providing insights into the effectiveness of the new design in generating controlled wind gusts.

Many combinatorial optimization methods and related optimization software, particularly those for mixed-integer programming, exhibit limited scalability when utilizing parallel computing resources, whether across multiple cores or multiple nodes. Nevertheless, high-performance computing (HPC) systems continue to grow in size, with increasing core counts, memory capacity, and power consumption. Rather than dedicating all available resources to a single problem instance, HPC systems can be leveraged to solve multiple optimization instances concurrently – a common requirement in applications such as stochastic optimization, policy design for sequential decision making, parameter tuning, and optimization-as-a-service. In this work, we study strategies for efficiently allocating solver jobs across compute nodes, exploring how to schedule multiple optimization jobs across a given number of cores or nodes. Using metrics from performance monitoring and benchmarking tools as well as metered PDUs, we analyze trade-offs between energy consumption and runtime, providing insights into how to balance computational efficiency and sustainability in large-scale optimization workflows.

In this work we present a node-level performance analysis of an adaptive resolution scheme (AdResS) implemented in ls1 mardyn . This is relevant in simulations involving a very large number of particles or long timescales, because it lowers the computational effort required to calculate short-range interactions in molecular dynamics. An introduction to AdResS is given, together with an explanation of the coarsening technique used to obtain an effective potential for the coarse molecular model, i.e., the Iterative Boltzmann Inversion (IBI). This is accompanied by details of the implementation in our software package, as well as an algorithmic description of the IBI method and the simulation workflow used to generate results. This will be of interest for practitioners. Results are provided for a pure Lennard-Jones tetrahedral molecule coarsened to a single site, validated by verifying the correct reproduction of structural correlation functions, e.g. the radial distribution function. The performance analysis builds upon a literature-driven methodology, which provides a theoretical estimate for the speedup based on a reference simulation and the size of the full particle region. Additionally, a strong scaling study was performed at node level. In this sense, several configurations with vertical interfaces between the resolution regions are tested, where different resolution widths are benchmarked. A comparison between several linked cell traversal routines, which are provided in ls1 mardyn , was performed to showcase the effect of algorithmic aspects on the adaptive resolution simulation and on the estimated performance.

In the scope of the dtec.bw project hpc.bw, innovative HPC hardware resources were procured to investigate their performance for HSU-relevant compute-intensive software. Benchmarks for different software packages were conducted, and respective results are reported and documented in the following, considering the Intel Xeon architecture used in the HPC cluster HSUper, AMD EPYC 7763 and ARM FX700.