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Turbulence Modeling Resource

 

 

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2D Backward Facing Step Validation Case

K-e-Rt Model Results
 

Link to k-e-Rt equations

K-e-Rt - backstep pressure coefficient K-e-Rt - backstep skin friction

K-e-Rt - backstep u-velocity profile upstream at x/H=-4 K-e-Rt - backstep u'v' profile upstream at x/H=-4

K-e-Rt - backstep u-velocity profiles K-e-Rt - backstep u'v' profiles

Note that thorough grid studies were not performed for validation cases such as this one. Some effort was made to ensure reasonable grid resolutions, but there may still be small noticeable discretization errors. Therefore, these validation results shown should be considered representative, but not "truth."

K-e-Rt results from CFD++ for ReH=36,000 are shown on the second-finest grid (257x257, 97x257, 385x449, 129x449). (Note that Cp values have been shifted so that Cp is close to zero near x/H=40.) CFD++ used freestream turbulence intensity=0.5% and freestream turbulent viscosity (relative to laminar)=10. Please read note 5 on Notes on running CFD page. Note that even though the solution converged well on this grid, there was a low-amplitude/high-frequency component to the RHS residuals; this slight unsteadiness likely caused the small "kink" visible in skin friction (near x/H=6) just prior to reattachment, associated with a small secondary bubble very near the wall. Reattachment is predicted near x/H = 6.3. Note that these are compressible code results at "essentially incompressible" conditions of M=0.128. There may be a very small influence of compressibility. Cp experimental data and CFD results have been shifted so that Cp is approximately 0 near x/H=40 (see brief discussion on Backward Facing Step Validation Intro Page).

Note that this model is currently assigned MRR Level 1 for the purposes of this website. This is because at this time the TMBWG has results for this model from only one code. The results on this page are therefore not necessarily reliable until additional independent code(s) can be used to verify the model implementation.


 
 

Jump to: SA Results,  SSTm Results,  SST-Vm Results,  Wilcox2006-klim-m Results,  K-kL-MEAH2015m Results,  EASMko2003-S Results

Return to: Backward Facing Step Validation Intro Page

Return to: Turbulence Modeling Resource Home Page


 
 

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Last Updated: 03/24/2020