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 Visual analysis of droplet dynamics in large-scale multiphase spray simulations(2021) Heinemann, Moritz; Frey, Steffen; Tkachev, Gleb; Straub, Alexander; Sadlo, Filip; Ertl, ThomasWe present a data-driven visual analysis approach for the in-depth exploration of large numbers of droplets. Understanding droplet dynamics in sprays is of interest across many scientific fields for both simulation scientists and engineers. In this paper, we analyze large-scale direct numerical simulation datasets of the two-phase flow of non-Newtonian jets. Our interactive visual analysis approach comprises various dedicated exploration modalities that are supplemented by directly linking to ParaView. This hybrid setup supports a detailed investigation of droplets, both in the spatial domain and in terms of physical quantities. Considering a large variety of extracted physical quantities for each droplet enables investigating different aspects of interest in our data. To get an overview of different types of characteristic behaviors, we cluster massive numbers of droplets to analyze different types of occurring behaviors via domain-specific pre-aggregation, as well as different methods and parameters. Extraordinary temporal patterns are of high interest, especially to investigate edge cases and detect potential simulation issues. For this, we use a neural network-based approach to predict the development of these physical quantities and identify irregularly advected droplets.Item Open Access Grundlagen der Theorie thermooptischer Aberrationen. II. Thermooptische Aberrationen der Vergrößerung(1968) Volosov, D. S.; Wagenknecht, Monika (Übersetzerin)Eine Theorie thermooptischer Aberrationen der Vergrößerung wird dargelegt, die die Änderung der linearen Bildgrößen bei einer Temperaturänderung bestimmt. Es werden allgemeine Bedingungen für die Temperaturunabhängigkeit eines optischen Systems aufgestellt, die bei seiner Berechnung erfüllt sein müssen.Item Open Access Grundlagen der Theorie thermooptischer Aberrationen. I. Thermooptische Aberrationen der Bildlage(1968) Volosov, D. S.; Wagenknecht (Übersetzerin)Dargelegt wird eine Theorie der thermooptischen Aberration der Bildlage, die für die Berechnung optischer Systeme, die die Lage der Bildebene bei Temperaturveränderung unverändert beibehalten, von Bedeutung ist. Die festgestellten Abhängigkeiten beziehen sich auf optische Systeme, die aus Gliedern endlicher Dicke bestehen und auf Systeme aus unendlich dünnen Gliedern.Item Open Access Grundlagen der Theorie thermooptischer Aberrationen. III. Thermooptische Aberrationen von Systemen aus dünnen Gliedern(1968) Volosov, D. S.; Wagenknecht, Monika (Übersetzerin)Auf der Grundlage der von uns aufgestellten Theorie thermooptischer Aberrationen wird ein allgemeines Durchrechnungsverfahren für optische Systeme aus dünnen Gliedern, die bei einer Temperaturänderung nicht gestört werden, untersucht. Jedes Glied kann seinerseits eine zusammengesetzte Kombination aus mehreren dünnen Linsen sein.Item Open Access Die Erhaltungssätze in der Relativitätstheorie und in der Kernphysik(1986) Pauli, Wolfgang; Pertschi, Ottmar (Übersetzer)Vorlesung Wolfgang Paulis an der N. D. Zelinskij-Universität für physikalische Chemie und chemische Verfahrenstechnik am 27.10.1937. Aus dem Deutschen Manuskript Paulis ins Russische übersetzt von Prof. I. E. TammItem Open Access Pauli in der UdSSR : Zur Frühgeschichte des Neutrino(1984) Frenkel, V. Ja.; Pertschi, Ottmar (Übersetzer)Unveröffentlichtes Manuskript von 1984 über Wolfgang Paulis Beziehungen zu Jakov I. Frenkel und L. D. Landau sowie über seine Rußlandaufenthalte 1925 - 1937Item Open Access Wolfgang Pauli, Wissenschaftlicher Briefwechsel mit Bohr, Einstein, Heisenberg u.a. Band 1: 1919 - 1929. New York ... : Springer, 1979(1981) Frenkel, V. Ja.; Pertschi, Ottmar (Übersetzer)Aus dem kurzen Überblick über den Inhalt des 1. Bandes des Briefwechsels von Pauli geht hervor, welch große Bedeutung das Buch nicht nur für Wissenschaftshistoriker hat, sondern auch für Physiker; für letztere dürfte es sehr aufschlußreich sein zu verfolgen, wie Ideen entstehen, sich entwickeln und in Fachaufsätzen niederschlagen.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.