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outlet -> inlet how?

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Old   June 28, 2010, 09:24
Default outlet -> inlet how?
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Benni
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Hi,

I don't know how to set an outlet velocity field result of a previous run as inlet velocity field in my present run.
Can anybody help me
Thanx
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Old   June 28, 2010, 09:35
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Hi,

You can try that (in your system file):

startFrom lastTime;
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Old   June 28, 2010, 10:15
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Benni
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Hi Norbert,

I have a case, in which my inlet (O/U) of the boundaryField is fixedValue, uniform (10 0 0).
my outlet is set to zeroGradient.
In a next case, I want to take the results of the outlet velocity field and set them as the boundary field of the inlet for the new case. Instead of fixedValue, I want to use the results of the old case.
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Old   June 28, 2010, 10:58
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Martin
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Hi Benni,

have a look at the mapFields utility: in the mapFieldsDict you can use the patchMap function.

http://www.openfoam.com/docs/user/mapFields.php

In your case the entry for patchMap might be:

patchMap (outlet inlet);

Preparations:
- define the appropriate mapFieldsDict in your second simulations "system" directory.
- use boundary condition fixedVelocity for the inlet of your second simulation with a dummy value of (0 0 0) initialized.

The command sequence is something like (replace the paths and the 1000):
cd path_to_second_simulation
mapFields path_to_first_simulation -sourceTime 1000

Check with paraview before starting the second simulation.

Martin
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Old   June 29, 2010, 05:28
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Benni
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Hi Martin,

thanx for your help.

I tried the second simulation with mapFieldsDict. The Field in paraview is o.k.

But I get the following error:

gradientInternalCoeffs cannot be called for a genericFvPatchField (actual type fixedVelocity)
on patch inlet of field U in file "/home/eggert/OpenFOAM/eggert-1.6/run/cube_cyclic/0/U"
You are probably trying to solve for a field with a generic boundary condition.

From function genericFvPatchField<Type>::gradientInternalCoeffs( ) const
in file fields/fvPatchFields/basic/generic/genericFvPatchField.C at line 782.

FOAM exiting


The other point is: I think mapFields is perhaps not the right tool for what I want to do. I have a 2-D case with inlet on the left and outlet on the right. In the middle of the mesh I have a box, which stands for a wall in a 3D case.
For every simulation step the velocity Field at the outlet would be the inlet for the next simulation step. This means, that this simulation will give the same solution as a simulation with many boxes in a row.
My problem is to generate the inlet velocity field for every step of the simulation.
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Old   June 29, 2010, 10:47
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Hi Benni,

I assume that the cyclic boundary condition is the BC you are looking for.

Since I don't have experience with it, you may have a look at these threads:

How to setup cyclic BCs in simpleFOAM

Cyclic Boundary Condition

This example in the OpenFOAMs tutorial directories might help, too:
tutorials/incompressible/channelFoam/channel395

Good luck

Martin
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