Enhanced wall turbulence model for flow over cylinder at high Reynolds number

Abstract

Modeling of turbulent flow over cylinders at high Reynolds numbers continues to be a challenge despite extensive work available in the literature. Most models suffer from loss of accuracy or require extremely refined grids both of which render their usage very difficult for practical problems. A wall model has been developed for solving supercritical turbulent flows using the Turbulent Boundary Layer Equations (TBLE). A new way to calculate the shear stress using the model has been introduced in this work. The TBLE model requires an input velocity from the off wall Large Eddy Simulation (LES) model. The method to obtain the same has been devised using the Log-Law. Also, the calculation of the turbulent viscosity in the near wall region has been modified by varying the Von Karman coefficient as a function of velocity in the adverse pressure gradient region. The results obtained with this enhanced TBLE model have been compared with other popular turbulence models for a Re of 1.0 × 106. The TBLE model has then been used to solve two more Re of 6.5 × 105 and 2.0 × 106. The performance of the model has been compared with respect to mean drag coefficient, Root Mean Square (RMS) of lift coefficient, Strouhal number, base pressure coefficient, adverse pressure recovery and separation angle as well as the profiles for pressure and shear stress variation over the cylinder. The model is shown to be fairly accurate, robust and computationally efficient on account of its ability to work with relatively coarse grids.