Dynamic unstructured method for flows past multiple objects in relative motion

Abstract

A new methodology is developed to simulate unsteady flows about objects in relative motion and compute the trajectory of their motion as determined by this flowfield. The method couples the fluid dynamics and rigid-body dynamics equations to capture the time-dependent interference between stationary and moving boundaries. The unsteady, compressible, inviscid (Euler) equations are solved on dynamic unstructured grids by an explicit, finite-volume, upwind method. For efficiency, the grid adaptation is perfomed within a window around the moving object. The Eulerian equations of the rigid-body dynamics are solved by a Runge-Kutta method in a noninertial frame of reference. This dynamic, unstructured flow solver is validated by computing the flow past a sinusoidally pitching airfoil and comparing these results with the experimental data. The trajectory code is tested by computing the six-degree-of-freedom trajectory of a store separating from a wing using the experimentally determined force and moment fields, then comparing with the experimental trajectory. Finally, the overall methodology is used for two two-dimensional examples: the flow past a pitching and plunging airfoil, and the free call of a store after separation from a wing section