COMPUTATIONS OF SEPARATED FLOWS WITH AN IMPROVED K-EPSILON MODEL.

THIS PROPOSAL IS TO SUPPORT NASA'S PROGRAM IN THE FIELD OF COMPUTER SIMULATIONS OF TURBULENT FLOWS OVER COMPLEX GEOMETRIES. THE INNOVATIVE TURBULENCE MODEL DESIGNED AT AMES RESEARCH CENTER BY MANSOUR, KIM AND MOIN (1987), CALLED THE MKM MODEL, WILL BE EXTENDED TO TREAT SEPARATED FLOWS. THE MKM MODEL IS A K-EPSILON MODEL DEVELOPED FROM A NEWLY-AQUIRED DATABASE OBTAINED FROM DIRECT SIMULATION OF A TURBULENT CHANNEL FLOW (KIM, MOIN AND MOSER 1987). THE MKM MODEL WILL BE IMPLEMENTED IN AN IMPLICIT REYNOLDS-AVERAGED NAVIER-STOKES CODE IN CURVILINEAR COORDINATES. THE EFFORT HAS TWO GOALS. ONE IS TO DEVELOP A USER-FRIENDLY MODULAR CODE. A FUNCTION OF THIS COMPUTER CODE IS TO PROVIDE A PRACTICAL TOOL FOR RESEARCHERS IN TURBULENCE MODELING TO TEST AND DEVELOP TURBULENCE MODELS. THE OTHER GOAL IS TESTING THE MKM MODEL. THIS WILL BE PERFORMED ON THREE TEST FLOWS: 1) A LOW-SPEED DIFFUSER FLOW,2) A BACKWARD-FACING STEP AND, 3) A SHOCK-BOUNDARY LAYER INTERACTION. NEW DAMPING FUNCTIONS FOR THE EDDY VISCOSITY WILL BE INTRODUCED. THEIR FORM WILL BE VERIFIED USING THE DATABASE PROVIDED BY THE DIRECT SIMULATION AND THEY WILL BE TESTED ON THE THREE ABOVE MENTIONED TEST PROBLEMS. DAMPING FUNCTIONS IN THE EPSILON EQUATION WILL ALSO BE INTRODUCED AND TESTED, WHILE THE TURBULENT-KINETIC-ENERGY EQUATION WILL RETAIN ITS HIGH-REYNOLDS NUMBER FORM.