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Free convection using chtMultiRegionSimpleFoam - implausible results

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Old   April 13, 2018, 21:02
Default Free convection using chtMultiRegionSimpleFoam - implausible results
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Peter Hess
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Dear openFoamers!

I am working on a very simple simulation with free convection driven by a heat source.

Unfortunately I am getting wrong results and can not find the missed part of the puzzle.

UBUNTU 17.10. server with kubuntu desktop. VMware Player is used.

openFoam 5.0.

Simulation:

- Two regions: Solid one in the middle and surrounded by the second which is air as perfect gas
- The solid region cubic form and has a heat source defined in fvOptions
- The fluid region is cubic and has gravity oriented in z direction
- Just the half of the regions calculated, since the geometry and the flow are symmetrical
- The outer boundary of the fluid should allow the flow to entre from the surrounding to the region from the bottom to the top and leave via free convection
- Laminar flow
- No radiation

The heat source should cause a flow in z direction in the opposite direction of z.

The problem I am facing here is that the flow (velocity profile) looks strange in paraFoam.

The geometry and the flow are symmetrical, well paraFoam shows something different.

Adding the turbulence and simulating without the symmetry did not corrected the mistake.

Run the simulation (more than 2000 iterations) and you will get the results shown below.

The zeroGradient for the velocity of the fluid surrounding (Out boundary) seams to make a problem.

Any suggestions?

Regards

Peter
Attached Files
File Type: gz CASE_FREE_CONVECTION.tar.gz (63.4 KB, 34 views)
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Last edited by peterhess; April 14, 2018 at 19:55.
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Old   July 8, 2018, 14:32
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Peter Hess
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Problem solved!

The conditions p_rgh has been modified.

See attached file.

Regards

Peter
Attached Files
File Type: gz Free_Conv_Works.tar.gz (30.1 KB, 75 views)

Last edited by peterhess; July 8, 2018 at 17:45.
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