Modelling laminar separation bubbles at low Reynolds number

Laminar separation bubbles is one of the main critical aspects of flows at low Reynolds number in the range 104 - 105. The flow separates in the laminar regime and the turbulence developing inside the re-circulation region enhances the momentum transport and the flow can re-attach. Models based on the Reynolds Averaged Navier Stokes equations suffer of two main issues. The determination of the transition onset and the level of the pressure recovery downstream the reattachment of the flow. This paper reports on the activities performed in the framework of a project set-up by a GARTEUR action group. Common test-cases have been performed by several institutions. The low Reynolds number flow around the SD 7003, EPPLER 387, and NACA 0015 airfoils are analyzed. The results are compared to experimental data and large eddy simulations available in literature. The comparison of different methods and models has allowed to individuate advice for the numerical simulation of the laminar separation bubbles.