The Porosity/Distributed Resistance (PDR) model is widely used for simulation of gas explosion in complex geometries. The current work presents a novel methodology to represent complex geometries as a porous media. The method is based on the Gilbert-Johnson-Keerthi (GJK) distance algorithm. The GJK concepts are applied to check the collision between a geometrical object and an element of a structured Cartesian grid. The parametrized geometry is coupled with CFD (Computational Fluid Dynamics) concepts in an ”in house” code developed by the Univesity of Campinas. The code comprises an explicit solver based on finite-volume method. The classical fourth order Runge-Kutta time marching approach is considered. The turbulence closure problem is addressed via two equations model. The combustion is based on flamelet formulation. The simulation of cold flow around bluff bodies is considered and good agreement is achieved.