Taking into account the influence of favorable pressure gradient for modeling the laminar-turbulent transition in the RANS approach

The problem of modelling the laminar-turbulent transition in the presence of a favourable pressure gradient is considered. Methods of modelling transient flows based on the solution of Reynolds equations are considered. A detailed analysis of the formulation of the laminar-turbulent transition model SST-y-alg from the LCTM family is given. It is demonstrated that this model does not reproduce the «drag bucket» effect in airfoil flow. A modification of the SST-y-alg model, which takes into account the influence of a favourable pressure gradient on the position of the laminar-turbulent transition, is proposed. The modification consists in increasing the critical Reynolds number in the region of favourable pressure gradient by means of an additional correction multiplier. To test the modified model, two problems are considered: laminar-turbulent transition on a plate and flow over an NLF(l)-0414F airfoil. It is shown that the application of the modified model leads to better agreement of computational and experimental data when modelling the natural transition scenario. It is also demonstrated that the modified SST-y-alg model reproduces the «drag bucket» effect with sufficient accuracy for practical applications.