how to calculate Cf inside a wall function
Dear foamers,
Could you tell me how to calculate Cf (friction coefficient) inside a wall function like alphatWallFunctionFvPatchScalarField.C ? I already have yPlus, rho and uStar=Cmu^(0.25)*k^(0.5). Code:
forAll(mutw, faceI) In order to be more accurate, can I calculate uTau with lines below? Code:
const fvPatchVectorField& U = Code:
scalar utau = 1) I know that I can recalculate the uPlus with yPlus to get sqrt(Cf/2), since uPlus=1/sqrt(Cf/2) 2) If I use the other definition of uPlus, the problem will be to know Ue in order to find Cf=tau/(0.5*Ue*Ue*rho). uPlus= Up*Cmu^(0.25)*k^(0.5)/(tau/rho) Even I adopt such calculation, how to get value of Up? Is it simply U[faceI]? I would like to know whether or not there is an easier way. Are the methods above acceptable? Are they correct in programming? Regards, aerothermal 
No clues on that?

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