Effects of adverse pressure gradient on near wall length scale in Reynolds-stress model

The Reynolds-stress model, as with most other models, has been calibrated for ''simple'' shear now i.e, zero pressure gradient boundary layer. Such calibration of the empirical constants does not provide universality because these constants are structural parameters which may change as flow structure changes. It is widely known that in adverse pressure gradient calculation, the near-wall length scale is overpredicted. By correlating the empirical constants in the epsilon-equation into a form analogous to length scale proportional to distance from the wall, it is found that the non-uniform near-wall shear stress profile is translated via the empirical constants into a larger than expected length scale. To overcome the problem a length-scale-limiting model was formulated to inhibit this increase in length scale by increasing the production of epsilon.