A modification of the k-kL-ω turbulence model for simulation of short and long separation bubbles

Abstract

The prediction of separation bubbles is highly important due to the controlling effects that they have on the airfoils performance. In the present study, a two-dimensional numerical simulation of the incompressible transitional flow around the NACA 0012 and Eppler 387 airfoils is studied. In order to examine the capability of the turbulence models for predicting the separation bubbles, several modified versions of the three-equation k-kL-ω turbulence model presented in previous research studies and the original four-equation SST k-ω turbulence model are compared with the experimental and Direct Numerical Simulation (DNS) data. A new modification based on the previous modified versions of the k-kL-ω model is also proposed. The Reynolds number based on the airfoil chord length is between 3 × 104 and 1.3 × 105. Simulation of the flow-field is performed by the solution of the Reynolds-averaged Navier–Stokes equations using a pressure-velocity coupling algorithm so-called RK-SIMPLER. An explicit method of second-order accuracy in time and space is used to integrate the momentum conservation equations. The results from this study indicate that the new proposed modification presents the better prediction for the separation bubbles than the previous versions, especially in the long separation bubbles. An excellent result is also obtained for the lift coefficients.