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#1 |
Senior Member
A. Min
Join Date: Mar 2015
Posts: 309
Rep Power: 13 ![]() |
Hi foamers
I want to find the exact location of separation point in flow around cylinder. According to fluid mechanics books, I should find the point (on the cylinder surface) in which shear stress is zero.(is it correct?) I calculate the xy component of stress tensor as: Code:
List<symmTensor> Tau00; List<scalar> Tau0; Tau00 = (tauS+tauP).boundaryField()[cylinder]; forAll(Tau00,i) { Tau0[i] = Tau00[i].xy(); } ![]() While streamlines show that separation is happened in teta=150: ![]() Could you please tell me what the problem is? Thanks |
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#2 |
Senior Member
Santiago Lopez Castano
Join Date: Nov 2012
Posts: 354
Rep Power: 16 ![]() |
Not only shear, but when the pressure gradient along the surface inflects from adverse to positive...
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#3 |
Senior Member
Michael Alletto
Join Date: Jun 2018
Location: Bremen
Posts: 616
Rep Power: 17 ![]() |
I think tau0.xy gives you the shear stress in the case of a flat plate which is parallel to the x-axis.
To get the shear stress in an arbitrarily defined surface in 3d the steps to perform are the following: 1) Project the shear stress tensor on the surface -> this gives you the vector of the force acting on the surface taus 2) Compute the dot product of taus with the vector pointing parallel to the surface -> this gives you the shear stress |
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#4 | |
Senior Member
A. Min
Join Date: Mar 2015
Posts: 309
Rep Power: 13 ![]() |
Quote:
Thanks for your reply. I rotated the stress tensor from xy to r-teta coordinates. I think this is correct, isn't it? |
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#5 |
Senior Member
Michael Alletto
Join Date: Jun 2018
Location: Bremen
Posts: 616
Rep Power: 17 ![]() |
yes this should be correct
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Tags |
cylinder, separation, shear stress |
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