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pressureGradientExplicitSource fvOptions - Problems on different meshes

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Old   December 3, 2015, 10:50
Default pressureGradientExplicitSource fvOptions - Problems on different meshes
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Hi all,
I am simulating a 2D-rib with periodic boundary conditions where OUTLET data is mirrored to INLET.
To keep the mass flow constant I am using pressureGradientExplicitSource in the fvOptions dictionary.

type pressureGradientExplicitSource;
active on; //on/off switch
selectionMode all; //cellSet // points //cellZone

fieldNames (U);
Ubar ( 1 0 0 );
gradPini gradPini [0 2 -2 0 0] 0; // initial pressure gradient
flowDir (1 0 0); // flow direction

So obviously I want to keep speed constant at 1m/s.
To look at avg(U) I select all cells of my geometry and use plotSelectionOverTime with only statistics chosen,
It works fine on a coarse mesh, consisting only of quadratic blocks (AR=1).

The velocity oscillates a little but becomes constant quickly at the desired value of 1.

But when I try to use a wall refined mesh

Velocity drops to 0.8 and remains there giving bad results for my simulation since I have to adjust a sink term for temperature according to mass flow (~velocity).

Does anybody has an idea what could cause this strange behaviour?

You can download my example calculation here:

Every help is appreciated!
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