2ND-ORDER NEAR-WALL TURBULENCE CLOSURES - A REVIEW

This paper summarizes the advances made to date in second-order near-wall turbulence closures. All closures examined are based on some form of high-Reynolds-number models. Consequently, most near-wall closures proposed to date attempt to modify the high-Reynolds-number models for the dissipation function and the pressure redistribution term so that the resultant models are applicable all the way to the wall. Furthermore, the near-wall closures examined solve a turbulence kinetic energy dissipation-rate equation to complete the closure. Again, the high-Reynolds-number form of the equation is modified to predict near-wall flow. The near-wall closures are examined for their asymptotic behavior so that they can be compared with the proper near-wall behavior of the exact Reynolds-stress equations. A comparison of the closures' performance in the calculation of a low-Reynolds-number plane channel flow is carried out. In addition, the closures are evaluated for their ability to predict the turbulence statistics and the limiting behavior of the structure parameters compared to direct simulation data. It is found that three second-order near-wall closures give the best correlations with simulated turbulence statistics; however, their predictions of near-wall Reynolds-stress budgets are incorrect. A proposed modification to the dissipation-rate equation remedies part of those predictions. Therefore, further improvements are required if a complete replication of all the turbulence properties and Reynolds-stres budgets by a statistical model of turbulence is desirable.