NUMERICAL MODELLING OF MIXING AND CHEMICAL REACTIONS IN TURBULENT FLOWS

WE SHALL DEVELOP METHODS TO SOLVE ONE OF THE CRITICAL PROBLEMS OF TURBULENCE MODELLING IN WHICH ALL TRADITIONALLY USED TURBULENCE MODELS FAIL, NAMELY MODELLING OF MIXING AND CHEMICAL REACTIONS IN COMPLEX TURBULENT FLOWS. WE PROPOSE TO DEVELOP A THREE-DIMENSIONAL COMPUTER CODE INCORPORATING RENORMALIZATION-GROUP (RNG) BASED DIFFERENTIAL TRANSPORT MODELS FOR TURBULENT HEAT, MASS, MOMENTUM TRANSFER COMBINED WITH CHEMICAL REACTION PROCESSES IN STRONGLY NON-STATIONARY, TURBULENT FLOWS. PRELIMINARY RESULTS FOR APPLICATION OF THESE NOVEL, NEW MODELS TO NON-STATIONARY AND SEPARATED FLOWS, INCLUDING FLOW OVER A BACKWARD-FACING STEP, OSCILLATORY PIPE FLOW, SHOCK-INDUCED SEPARATION ON AN AIRFOIL, AND LOW AND HIGH PRANDTL NUMBER TURBULENT HEAT TRANSFER SUGGEST THAT THE MODELS WILL BE VERY EFFECTIVE FOR THE PRESENT CLASS OF DIFFICULT FLOWS. IN ADDITION, RECENT EXTENSIONS OF THE RNG METHOD GIVE A DESCRIPTION OF TURBULENT COMBUSTION THAT PROMISES SIGNIFICANT ADVANCES IN OUR ABILITY TO MODEL REACTING FLOW PROBLEMS.