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#1 |
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Juan
Join Date: Jun 2024
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Hi!
A did a simulation in Fluent about a straight pipe with a velocity profile as inlet = 0.05 m/s as maximum velocity, and pressure outlet = 0 at Outlet. The fluid is water included in Fluent database. Using the Darcy equation: DeltaP = rho * f * L * V^2 / D where Re = 498 f = 64 / Re = 0.128 I get DeltaP = 3.2 Pa (same as calculator online). The problem is that I get 1.6 Pa in Fluent. I have used Laminar flow, k-w SST and k-e realizable. All of them obtain the same value and mass flow net is equal to e-11. I had change the mesh and I did refinement but value does not change. Residuals go below 1e-6. What am I missing? The pipe has dimensions: Long = 200mm Diameter = 10mm |
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Kareem
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#3 |
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Juan
Join Date: Jun 2024
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In the inlet I have applied a name expression:
f(r) = Umax * ( 1 - (r/R)**2) Where Umax is the velocity 0.05 m/s, r is defined as sqrt(z**2 + x**2) and R = D/2. Pipe is along Y axis. This function I understand is for a developed laminar flow so I can use Darcy equation, isn’t it? Edit: if I use the mean velocity = 0.025 m/s I get DeltaP = 1.6 Pa which is the value obtained in Fluent. So mean velocity is needed in equation right? Last edited by Xatkor; June 5, 2024 at 05:30. |
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Tags |
fluent, missmatch, theorical solution, wrong value |
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