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Same pressure gradient but different velocity field

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Old   April 24, 2018, 04:37
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Filippo Maria Denaro
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Originally Posted by TurbJet View Post
I kind of figured this out. 1st case will be Poiseuille flow and it follows the parabola profile. But for 2nd case, it's not Poiseuill flow, the velocity profile will not be parabola. It has much larger gradient at near wall region to balance the pressure gradient, so the entire velocity field is smaller than the 1st case.

I think this solution has not really reached a convergence to steady state. If it does not converge that should confirm a bug in setting the BC.

PS: are you using a small Re number?
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Old   April 28, 2018, 01:46
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Originally Posted by FMDenaro View Post
I think this solution has not really reached a convergence to steady state. If it does not converge that should confirm a bug in setting the BC.

PS: are you using a small Re number?
Actually, fixed total pressure at the inlet will give a different velocity profile. So it seems we cannot simply compare with Poiseuille solution.
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Old   April 28, 2018, 04:35
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Originally Posted by TurbJet View Post
Actually, fixed total pressure at the inlet will give a different velocity profile. So it seems we cannot simply compare with Poiseuille solution.

At the steady state the solution has a constant velocity along x, therefore (p0_inl=p_inl + k_inl) and (p0_out=p_out + k_out) being k_out=k_inl should provide the same pressure difference.
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pressure and velocity, pressure boundaries, viscous laminar

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