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How does FLUENT caculate velocity profile at wall when shear is specified?

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Old   June 4, 2021, 08:54
Default How does FLUENT caculate velocity profile at wall when shear is specified?
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Faizan
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Dear all,

I am doing simulations for laminar flow in a 2D rectangular channel where a wall is modelled with specified shear (against the flow direction using a udf prescribed profile (for example using linear or sinusoidal functions.) Although, the udf profile works fine and the wall shear stress remains as specified, I am not able to understand how does Fluent calculates the corresponding velocity profile at the wall. I have tried comparing velocity profile from Fluent with that calculated using integration of tau=mu *du/dy but the velocity is significantly smaller in FLUENT.

Does anybody know how does velocity profiles is implemented in FLuent when shear stress is specified?

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Faizan
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Old   June 4, 2021, 19:13
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Lorenzo Galieti
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Which viscosity did you use? Are you perhaps running a turbulence model?
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Old   June 5, 2021, 12:04
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Faizan
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Hi Lorenzo,

I have tried constant viscosity as well as temperature dependent viscosity using udf (not needed for base case with only flow) for this case. I am not using any turbulence model. My flow strain calculation is correct given as du/dy=stress/viscosity but apparantly Fluent is calculating velocity in some different way. Any ideas?

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Faizan
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