HLPW-4: Case 3 Turbulence Model Verification

The purpose of the study is to demonstrate the accurate and consistent implementation of the standard Spalart-Allmaras turbulence model combined with RANS. This means that different flow solvers should reach the same solution if they all use the same mesh refinements, turbulence models and inputs.

The verification of a solvers code is an important activity because codes with supposedly the same turbulence model are often compared at workshops, however they often contain hidden implementation differences without the user’s knowledge, this can make it difficult to assess the influence of other parameters such as the mesh or other numerics. Thus, making it difficult to validate CFD results to experimental results.

For this study verification is done using code-to-code comparison, the results are compared to baseline solutions from FUN3D. The implementation of SA in FUN3D has been verified using the method of manufactured solutions. As expected, the code approaches consistent results as the grid is refined. It is expected that Fluent as well as other codes should agree with the baseline solution. If they do not, then it is possible that a different version of SA is implemented or there are mistakes or bugs in the code.

Case Description

The geometry being investigated is a high lift version of the Common Research Model (CRM-HL). The geometry was developed by NASA to be representative of a typical high-lift configurations found on modern commercial aircraft. The test case is a two-dimensional section of the CRM-HL with deployed slat and flap elements. The local chord is 1 meter (measured with the flap and slat stowed). The slat and flap deflections are 30 and 37 degrees, respectively.

The main case is run at an angle of attack of 16°, at Mach 0.2 with a Reynolds number of Re = 5 million (based on stowed airfoil chord length), the parameters of the case are summarised in the table below.