ISBN 9783843955621

978-3-8439-5562-1, Reihe Ingenieurwissenschaften

Pascal Mossier
An hp-Adaptive Strategy for Compressible Droplet Dynamics with Phase Transition

197 Seiten, Dissertation Universität Stuttgart (2024), Hardcover, A5

Zusammenfassung / Abstract

The process of phase transition is a defining characteristic of multiphase flows and at the heart of fundamental environmental processes. In engineering, the understanding and reliable prediction of multiphase flows with phase transition is essential for current and future propulsion systems of airliners and orbital launch systems. Despite their importance, high-fidelity simulations of multiphase phenomena remain a challenge due to their inherent multiscale character. While continuum models are well suited to describe fluid flow on a macroscopic scale, the phase transition process is governed by molecular interactions on a microscopic scale, necessitating a consistent coupling of interfacial hydrodynamics and thermodynamics. Moreover, compressible flow fields and severely deforming interface geometries pose a multiscale problem in itself with intricate vortical structures, strong discontinuities at shocks and surface instabilities. This thesis presents an innovative methodology to tackle such multiscale problems on a modeling, discretization and computational level. At phase boundaries, scale-bridging coupling of hydrodynamics and thermodynamics is achieved with an interfacial Riemann problem, which incorporates a local phase transition model. To meet the dynamic resolution requirements of the flow field, a novel hp-adaptive hybrid Discontinuous Galerkin and Finite-Volume discretization scheme is introduced. Finally, the thesis covers the implementation of a dynamic load-balancing scheme that allows for scalable computations on massively parallel high-performance computers. The method’s accuracy and efficiency are analyzed with gas-dynamics and droplet-dynamics benchmarks, showcasing its scalability and reliable detection and tracking of shocks, vortical structures, and phase boundaries. Following validation against molecular dynamics data, the framework is employed to simulate a shock-droplet interaction with phase transitions in full three space dimensions.