Calculation of Turbulence Intensities and Shear Stresses on Concave Surfaces by Extending the Low Reynolds Turbulence Model for Curved walls

In this paper we examine the effect of concave curvatures on turbulent flows using numerical solutions of boundary layer equations on concave surfaces. Turbulence intensities and turbulent shear stress were calculated in the mentioned case. It is obvious that the turbulent intensities and turbulent shear stress are increased on concave walls compared with flat plates under the same conditions. It was concluded that for the boundary layer on concave surfaces, the destabilizing effects lead to increased turbulent momentum exchange between fluid particles similar to the way concave curvature causes flow to be destabilized.The rate of integral parameters of the boundary layer such as momentum thickness and displacement thickness are increased on concave curvatures when they are compared to the values of these parameters on flat plates. However, the nonlinear k-ε model often used in engineering applications cannot satisfy the distribution and wall-limiting behavior of the Reynolds stress component. In this case, the model used to calculate turbulent parameters is an improvement over low Reynolds number turbulence models. It is modified by both wall functions and curvature parameters for curved surfaces. This extended model is introduced for the first time in this paper.