Law of the wall plot
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Hi all,
My case is a turbulent pipe flow which has been simulated in openFoam v7. I wanna plot famous uplus-yplus graph (law of the wall) like the attached image and I don't know what shall I do? |
Well, you could use the sample utility to extract the velocity at the wall. Use some software (e.g. matlab, excel, python, whatever you prefer) to calculate your non-dimensional u+ and y+ and plot it. You would need to calculate the wall shear stress for this - I believe there might be a tool for this in OpenFOAM.
It's not as straightforward as I would like it to be, maybe someone has a better idea to get this more convenient. |
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These functions give you the value at the first nodal point at the wall. What you need is the velocity profile at the wall. For example, you use the sample utility to get u and y over a line. Then you need to calc u+ and y+ by yourself before plotting.
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If so could you please share the methodology? Will be really helpful. |
Generate a set of probes, normal to the wall, and output the mean velocity at each probe location. Also extract the wall shear stress, so that you can calculate u*. Now calculate U+ = U/u* and y+=y.u*/nu for each probe location and hey presto you can plot U+ vs y+.
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