Simulation of reactive flows using particle methods

Abstract

We describe a new computational method for the numerically stable particle-based simulation of open-boundary flows, including volume conserving chemical reactions. The novel method is validated for the case of heterogeneous catalysis against a reliable reference simulation and is shown to deliver identical results while the computational efficiency is significantly increased. K E Y W O R D S reactive flow, particle based fluid mechanics, pressure boundaries 1 | INTRODUCTION In particle-based fluid simulation methods, pressure boundary conditions, also called open boundaries are notoriously problematic since either the inflow into the simulation domain or the outflow out of the domain is not known à priori. Instead, it depends on the difference of the external pressure given as a boundary condition and the internal pressure which is part of the solution of the hydrodynamic problem itself. Thus, we have the peculiar situation that the quantity we can control at the boundary in particle-based fluid simulation, namely the material flux, is unknown.A prototypical problem is a water pipe which is fed from a constant pressure source at one side and emptied against atmospheric air pressure at the other side. According to the paradigm of particle-based hydrodynamics, quasi-particles enter and leave the pipe at both sides in quantities given by the rules of hydrodynamics. The problem of the computational method of particle-based hydrodynamics is to determine the frequency at which particles are inserted into or extracted from the simulation domain as well as the velocities of the inserted particles. If the hydrodynamic fields of pressure, temperature and flow velocity would be know at the boundaries, that is, if Dirichlet boundary conditions for all relevant macroscopic fields are assumed, the injected and extracted particles can be drawn from a probability distribution function [1].