(65ay) A Novel Open Source CFD Code for Explosion Modelling

The porosity parametrization of complex geometry is very important in explosion simulation. This project proposes a novel approach to calculate the mesh porosity (volume and area) based on the Gilbert–Johnson–Keerthi (GJK) distance algorithm. The GJK algorithm can be used to check the collision between convex objects. This concept is used in the current work to check the collision between an element of the mesh and an object of the geometrical model. The parametrized geometry is combined with the combustion model based on flamelet formulation in accordance with BML (Bray-Moss-Libby) model. The typical chemical libraries are replaced by the integral length scale of wrinkling based on semi-empirical formulation. One simple step reaction mechanism is considered. The turbulence closure problem is addressed via Boussinesq formulation using two equations model for turbulent kinetic energy and the rate of dissipation of turbulent kinetic energy.

The CFD (Computational Fluid Dynamics) solver relies on an explicit finite-volume code based on a structured Cartesian grid. The classical fourth order Runge-Kutta time marching approach is considered. The PDR (porosity distributed resistance) approach is used to model all geometry under analysis (including the large-scale objects and the small ones). The central differencing scheme is applied to discretize the governing equations and artificial viscosity is used to smooth out numerical wiggling. Additional resistance terms are considered in the momentum equation. Additional generation source term for turbulence is considered in the turbulent kinetic energy equation. The simulation of standard flow across different geometries presented consistency with the literature. Good agreement is found for similar simulations using a commercial CFD software. The developed open CFD code seems to be promising as an alternative to solve complex explosion problems from the engineering view point.