Author Topic: Problem of over-predicting tangential velocity near the wall in swirling flow  (Read 1606 times)

Offline piso

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Hi,

I am getting a very high tangential velocity profile magnitude in Fluent. The flow is highly swirling flow. I can not understand why this is happening. I am using RSM with second order upwind scheme for turbulence.

I would appreciate any help in this matter.

Thank you in advance.


Offline william

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Hi,

In high-swirl rotating turbulent flows, the default settings for the Reynolds Stress Model and wall function can lead to erroneous predictions of the velocity profiles near rotating walls such that there is unphysical dissipation of the swirl in the outer region. The tangential velocity is flatter and decays more slowly resulting in an over-prediction of tangential velocity near the wall.

Steady-state solver
Green-Gauss cell-based solver
Pressure-based Coupled Solver
Relative velocity formulation

Turbulence Model = RSM
Options
Linear strain
Wall reflection option OFF to avoid impact on swirl
Near-wall Treatment = Non-equilibrium wall function

Discretization
Pressure = PRESTO
Momentum = MUSCL
Turbulence = Second-order upwind

Solver Controls
Courant number = 100
Under-relaxation Factors
Pressure, Momentum = 0.5
Turbulence = 0.1 (can be increased)