Validation of the Fokker-Planck chemistry implementation with the RFZ-ST2 upper stage

We test the chemistry implementation of our kinetic Fokker-Planck (FP) method for an industrial scale space transport problem. We use the FP method as it is able to simulate flows in the rarefied regime above the continuum limit, as found at high altitudes. The FP method provides this physical modelling advantage of a particle method with the computational efficiency needed for the simulations of industrial scale applications. We compare FP simulations of the generic RFZ-ST2 upper stage to computational fluid dynamics (CFD) Navier-Stokes simulations with the DLR TAU code. We use an artificial flight Mach number of M a = 15 to facilitate chemical reactions. We limit ourselves to dissociation and exchange reactions. We compare the flow fields and the surface distributions to validate the implementation. This is done as a step towards the simulation of re-usable launch vehicles at high altitudes in re-entry and re-entry burn situations.