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convergence problem with simpleFoam

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Old   July 19, 2017, 18:07
Post convergence problem with simpleFoam
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Hi All,

I am simulation a flow in a cylinder in order to get a velocity distribution at outlet, which i will use as inlet in another case.

in my current case, i'm using simleFoam, a wedge of a cylinder with 6mm radius, and 10 cm long. boundary conditions for pressure are zeroGradient every where except the outlet it was set to zero value. velocity boundary condition was set as fixedValue of zero at wall, zeroGradient at outlet, and flowRateInletVeloctiy at inlet. two sides were set as wedge in both blockMeshDict and boundary files. the axis of symmetry we set as empty in both blockMeshDict and boundary files. Re is 100.

tolerances for linear solver were set as 10^-9 for pressure and velocity, and zero for relative tolerances. also, residual was set to 10^-9.

GAMG was used for pressure with gaussSeidel smosther. smoothSolver was used for velociy with gaussSeidel smoother.

when i ran the solver for up to 10000 iteration, all fields initial residuals are fall below 10^-9 except Ux is stuck on 0.0035 initial residual. x is axis of symmetry and the direction of flow.
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Old   July 20, 2017, 10:23
Default repeating the simulation with icoFoam
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Hi there,

I have repeated the simulation using icoFoam solver, i have changed time step to get suitable Courant number, and it ran for 10 seconds.

at the end, iíve got a parabolic profile of velocity at the outlet, the initial residuals of all fields fall below 10^-9, except of Ux again (it stuck on 0.016).

thanks.
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