Development of an external ballistics simulation software

Körpe, Serkan Berkay
A fully automatic external ballistic CFD analysis software is developed in C++ for the purpose of acquiring instant aerodynamic properties, particularly pressure based drag coefficient during the free flight of any intended flat based or boat tailed projectile. To eliminate any dependency on other commercial or third party software, a three-dimensional Computational Fluid Dynamics (CFD) analysis code is developed for the entire analysis process including a three-dimensional geometry modeler and surface mesh generator, an adaptively-refined Cartesian volume mesh generator, an Euler solver and a motion solver. Characteristic equations of a projectile are embedded to the surface modeler to draw the two-dimensional outline of it. Then, the three-dimensional surface is generated by revolving the two-dimensional outline around the centerline. Triangular surface mesh of the projectile is created by using the point cloud over the surface. Surface mesher module of the software creates output mesh file for the usage of Cartesian volume mesh generator. Volume mesh generation process starts by creating the root cell and uniform mesh. Neighboring relativities are set during the cell creation. The intended projectile is fitted into uniform mesh by using the triangular surface mesh file. The inside – outside states of the cell corners are determined by the ray-casting approach. Depending on the states of the corners, the cell types are specified. Then, the cut cells are formed by the marching cubes method. Euler equations are solved for determining the flow field around a projectile. Finite volume method is used for the discretization of the equations. Solution-adaptive mesh refinement is applied to the developed flow solver. Finally, the trajectory of a projectile is calculated by using the developed motion solver.