Numerical Study on Transitional Flows Using a Correlation-Based Transition Model

A correlation-based transition model is assessed against distinct test cases. The configurations include a zero-pressure-gradient flat plate, a single-element aeronautical airfoil, a multielement high-lift airfoil and a wing–body configuration. These test cases are selected in order to cover different transition mechanisms in increasingly complex scenarios. The simulations are performed considering the compressible preconditioned Reynolds-averaged Navier–Stokes equations, which are one of the options offered by the CFD++ finite volume solver. Turbulence closure is achieved with the shear-stress transport model. This turbulence model is augmented by a transition model based on two additional transport equations: one for the intermittency, and another for the momentum-thickness Reynolds number. Flow parameters, such as freestream turbulence intensity and turbulence length scale, or the eddy viscosity ratio, have important effects on transition onset and extension of the transition region. Mesh refinement and y+ dependence are numerical parameters investigated in this work. The dimensionless wall distance y+ has a significant impact in the computational results. The transition model is also very sensitive to the inflow boundary conditions for the turbulence variables, namely, the freestream turbulence intensity and the eddy viscosity ratio. Good agreement with the experimental data is observed.