The method and system for aiding in the design of an automotive vehicle enables dynamic placement of particle injection points into a flow domain to permit visual observation and alteration of resulting particle trajectories with respect to a computer aided design model representative of the vehicle. Various particle trajectories, representing windshield washer spray, water droplets along the vehicle surface, and the like can be simulated relative to the vehicle surface with or without the influence of a flow field around the vehicle surface to evaluate a vehicle design, compare alternate designs and compare results from physical aerodynamic tests to predicted results.