Timon Hitz

• Dr.-Ing.
• Wandelbots GmbH

The computation of two-phase flow scenarios in a high pressure and temperature environment is a delicate task, for both the physical modeling and the numerical method. In this article, we present a sharp interface method based on a level-set ghost fluid approach. Phase transition effects are included by the solution of the two-phase Riemann problem...

The isothermal Navier-Stokes-Korteweg system is a classical diffuse interface model for compressible two-phase flow which grounds in Van Der Waals' theory of capillarity. However, the numerical solution faces two major challenges: due to a third-order dispersion contribution in the momentum equations, extended numerical stencils are required for th...

The Riemann problem is one of the basic building blocks for numerical methods in computational fluid mechanics. Nonetheless, there are still open questions and gaps in theory and modelling for situations with complex thermodynamic behavior. In this series, we compare numerical solutions of the macroscopic flow equations with molecular dynamics simu...

This paper describes improvements of a level-set ghost-fluid algorithm in the scope of sharp interface multi-phase flow simulations. The method is used to simulate drop-drop and shock-drop interactions. Both, the level-set and the bulk phases are discretized by a high order discontinuous Galerkin spectral element method. The multi-phase interface a...

The isothermal Navier-Stokes-Korteweg system is a classical diffuse interface model for compressible two-phase flow. However, the numerical solution faces two major challenges: due to a third-order dispersion contribution in the momentum equations, extended numerical stencils are required for the flux calculation. Furthermore, the equation of state...

Multiphase flows often occur under extreme ambient conditions, such as high temperatures or pressures and in the vicinity of the critical point. In these regimes, the flow is considered compressible and there is a strong coupling between the hydrodynamic behaviour and thermodynamic processes. This poses a great challenge to numerical methods that s...

The Riemann problem is a fundamental concept in the development of numerical methods for the macroscopic flow equations. It allows the resolution of discontinuities in the solution, such as shock waves, and provides a powerful tool for the construction of numerical flux functions. A natural extension of the Riemann problem involves two phases, a li...

Operating fluids for steering and propulsion of orbital manoeuvring systems are to be changed from toxic substances to environmentally less harmful alternatives. Liquid oxygen (LOX) can be used as oxidizer but the near vacuum conditions of outer space lead to a fast expansion into a superheated state when LOX is injected into the combustion chamber...

The use of complex multi-parameter equations of state in computational fluid dynamics is limited due to their expensive evaluation. Tabulation methods help to overcome this limitation. We propose in this work a tabulation approach for real equations of state that is also suitable for multi-component flows and multi-phase flows with phase transition...

Common fuel-oxidizer combinations in orbital manoeuvring systems consist of toxic substances but will be replaced in the future. Liquid oxygen (LOX) is one potential oxidizer but it rapidly superheats under the initial low-pressure conditions in the combustion chamber. Bubble nucleation and growth dominate the efficient disintegration of the liquid...

The present work analyses the growth of multiple bubbles in superheated liquid jets by means of direct numericalsimulations (DNS). A discontinuous Galerkin approach is used to solve the Euler equations and an adequate in- terface resolution is ensured by applying finite-volume sub-cells in cells with interfaces. An approximate Riemann solver has be...

The main objective of this presentation is the simulation of trans-critical fluid flows. In this context we discuss issues like: General Equations of State, Phase transition in the context of Homogeneous Equilibrium assumption, Spurious Oscillations due to real EOS and multi-components, Double flux in the context of tabulated EOS and DG methods.

The present investigation considers determination of entropy production from the flow field around a turbine guide vane, and the numerical simulation of this flow field by means of Computational Fluid Dynamics (CFD). These CFD simulations are based upon RANS, the Reynolds Averaged Navier-Stokes equations, and are carried out using ANSYS CFX-14.0 an...

In this work we apply the high-order discontinuous Galerkin spectral element method (DGSEM) with explicit Runge-Kutta time integration to a classical square duct channel flow problem, which is a widely used benchmark case for turbulent flows. We show that due to its good scale resolving capabilities and low dispersion and dissipation errors DGSEM i...