Interactive visualization of fluid dynamics simulations in locally refined cartesian grids

This work presents interactive flow visualization techniques specifically adapted for PowerFLOW^TM, a lattice-based CFD code from the EXA corporation. Their Digital Physics^TM fluid simulation technique is performed on a hierarchy of locally refined cartesian grids with a fine voxel resolution in areas of interesting flow features. Among other applications the PowerFLOW solver is used for aerodynamic simulations in car body development where the advantages of automatic grid generation from CAD models is of great interest. In a joint project with BMW and EXA we are developing a visualization tool which incorporates virtual reality techniques for the interactive exploration of the large scalar and vector data sets. In this paper we describe the specific data structures and interpolation techniques and we report on fast particle tracing taking into account collisions with the car body geometry. An OpenGL Optimizer based implementation allows for the inspection of the flow with particle probes and slice probes at interactive frame rates.