Fluids

Fluids

Skin Friction over an airfoil

    • qamar
      Subscriber
      Hello Everyone, I am new to this forum. I was looking into skin friction coefficient issues. I am doing steady analysis of an airfoil using Transition SST model. I did meshing in ICEM with yplus less than 1. I am obtaining skin friction coefficient from plot-wall flux-skin friction coefficient. But the coefficient does not matches with the literature data. My lift and drag coefficients are in good match with experimental values.nnSecondly, the export of skin friction data set is plotted with random lines in the graph. I do not know the issue.nWhat may be the issue with skin friction coefficient?. Am I plotting it the wright way? Kindly help accordingly. Thank you very much.n
    • Karthik R
      Administrator
      Hello,nYou might be using an incorrect reference value. The skin friction coefficient uses the reference density and velocity. Please check the results with which you are attempting to compare your results, find out the their reference value, and use the same value in Fluent. nRegarding your second question - could you please share a screenshot of the plot here. Please embed the screenshot directly into the post.nThank you.nKarthikn
    • qamar
      Subscriber
      Hi Kremella,nThank you very much for your reply. Sorry for the late response. I am considering the same values of density and velocity in Reference values in Fluent, but still I am not obtaing the desired results. I will look into it again.nSecondly, I am attaching the pictures of fluent Cf and Cf plotted after data is exported in .csv format. You can see the strange lines in the plot.nnThank you.nn
    • DrAmine
      Ansys Employee
      I saw these kind of lines if one is exporting node values and /or wrong line (duplicated lines). Is you mesh 2D or 3D? Are you exporting along a line (edge) or surface? If surface I can think that you get these kind of plots.n
    • qamar
      Subscriber
      Thank you for your rely. I am taking airfoil surface, this may be the reason. I will take upper and lower surface separately. I will look into it.nnThank you.n
    • Karthik R
      Administrator
      Yes, that should definitely help. n
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