13 Zentrale Universitätseinrichtungen
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/14
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Item Open Access Performance comparison of CFD microbenchmarks on diverse HPC architectures(2024) Galeazzo, Flavio C. C.; Garcia-Gasulla, Marta; Boella, Elisabetta; Pocurull, Josep; Lesnik, Sergey; Rusche, Henrik; Bnà, Simone; Cerminara, Matteo; Brogi, Federico; Marchetti, Filippo; Gregori, Daniele; Weiß, R. Gregor; Ruopp, AndreasOpenFOAM is a CFD software widely used in both industry and academia. The exaFOAM project aims at enhancing the HPC scalability of OpenFOAM, while identifying its current bottlenecks and proposing ways to overcome them. For the assessment of the software components and the code profiling during the code development, lightweight but significant benchmarks should be used. The answer was to develop microbenchmarks, with a small memory footprint and short runtime. The name microbenchmark does not mean that they have been prepared to be the smallest possible test cases, as they have been developed to fit in a compute node, which usually has dozens of compute cores. The microbenchmarks cover a broad band of applications: incompressible and compressible flow, combustion, viscoelastic flow and adjoint optimization. All benchmarks are part of the OpenFOAM HPC Technical Committee repository and are fully accessible. The performance using HPC systems with Intel and AMD processors (x86_64 architecture) and Arm processors (aarch64 architecture) have been benchmarked. For the workloads in this study, the mean performance with the AMD CPU is 62% higher than with Arm and 42% higher than with Intel. The AMD processor seems particularly suited resulting in an overall shorter time-to-solution.Item Open Access Particle-resolved simulation of the pyrolysis process of a single plastic particle(2024) Zhang, Feichi; Tavakkol, Salar; Galeazzo, Flavio C. C.; Stapf, DieterParticle-resolved simulations have been performed to study the pyrolysis process of a high-density polyethylene (HDPE) particle in an inert hot nitrogen flow. The simulations resolve the velocity and temperature boundary layers around the particle, as well as the gradients of temperature and concentration within the particle. The objective of this work is to gain an in-depth understanding of the effect of particle morphology-specifically, the particle size and shape-on the interplay between heat transfer and pyrolysis progress, as well as to assess the applicable particle size when using the Lagrangian concept for simulating plastic pyrolysis. In all simulation cases, the pyrolysis reaction is initiated at the external surface of the particle, where the particle is heated the fastest. The reaction front propagates inward toward the core of the particle until it is fully pyrolyzed. For particle diameters larger than 4 mm, distinct temperature gradients within the particle can be detected, leading to a temperature difference of more than 10 K between the core and the external surface of the plastic particle. In this case, the Lagrangian simulations yield a considerably slower conversion compared with the particle-resolved simulations. Moreover, the cylindrical particle in longitudinal flow has been found to be pyrolyzed more slowly compared with the spherical and shell-shaped particles, which is attributed to the enhanced heat transfer conditions for the cylindrical particle. The results reveal the importance of considering particle morphology when modeling plastic pyrolysis. In addition, the Lagrangian approach, which assumes particle homogeneity, is only applicable for particle diameters smaller than 2 mm when modeling plastic pyrolysis.