The results obtained from a priori channel-flow tests show that the dissipation terms of some tested low-Reynoldsnumber models possess correct near-wall behaviors, whereas those obtained from a posteriori full computations by the same tested models do not. Such a contradiction is clarified comparing the behaviors extracted from exact analysis and particular models. Solutions of approximate near-wall equations show that the models produce overprediction in the viscous sublayer due to lower orders of leading turbulent-stress terms than in conventional expansions depending on a wall-normal coordinate. The modifications of dissipation-tensor and pressure-containing term approximations using a new geometry-independent "near-wall" tensor are proposed. This corrects the near-wall behaviors for the lowest-order Reynolds-stress expansion terms and improves prediction accuracy, particularly in the secondary recirculation zone of a turbulent flow behind a backward-facing step.
All Science Journal Classification (ASJC) codes
- Aerospace Engineering