conjugateHeatTransfer solver, Problem with DT-surface-field

gmoehl · February 4, 2015, 08:44

Hi,

I've got a problem using the conjugateHeatTransfer-solver from OpenFoam 1.6 extended.
The problem seems to lie somewhere in the interpolation of the DT-Field at the surface and seems to be similar to the one brought up by the user 'benk' in this discussion: http://www.cfd-online.com/Forums/ope...penfoam-8.html

I tried to simulate a simple conduction problem. Therefore I created two simple boxes, one for the solid and one for the fluid region and only varied the DT-Value in both regions:

DT_solid = 1
DT_fluid = 10

The temperature-BC for the wall opposite of the surface in the fluid region is a constant value and on the opposing wall in the solid region the gradient is set to a constant value.

I uploaded a figure of the temperature distribution after the simulation was run.
In the figure, the solid line shows the distribution, yielded from the simulation and the dashed line shows the analytical solution, that should evolve.

https://www.dropbox.com/s/rhf42dm0aq..._wall.png?dl=0

The problem is, that the solver doesn't use the harmonic mean (= 1.818) to calculate the heat transfer over the surface but the arithmetic mean (= 5.5). This leads a lower Temperature-gradient between the two cells on each side of the surface, yielding a lower Temperature in the first solid cell. So while the gradient in the solid and fluid field is right, the absolut temperature value isn't.
The weird thing is that The DT-field that is saved at the end is actually right, the value at the surface is 1.81 on both sides. So the solver calculates the right value but doesn't use it.

I've tried everything mentioned in the older thread and havn't found a solution yet.

Thanks for your help in advance!

gmoehl · February 9, 2015, 03:07

Sooo, no one has an idea?
has anyone tried out the sover in the new 3.0-extended edition?

gmoehl · February 11, 2015, 09:48

It looks like this problem doesn't occur in the current solver, so I'm gonna work with this one.
Nevertheless it would be interesting to know why this error occurs in the older version, so if you know it would be nice if you enlighten me ;-)

February 4, 2015, 08:44	conjugateHeatTransfer solver, Problem with DT-surface-field	#1
gmoehl New Member Join Date: Aug 2012 Posts: 12 Rep Power: 14	Hi, I've got a problem using the conjugateHeatTransfer-solver from OpenFoam 1.6 extended. The problem seems to lie somewhere in the interpolation of the DT-Field at the surface and seems to be similar to the one brought up by the user 'benk' in this discussion: http://www.cfd-online.com/Forums/ope...penfoam-8.html I tried to simulate a simple conduction problem. Therefore I created two simple boxes, one for the solid and one for the fluid region and only varied the DT-Value in both regions: DT_solid = 1 DT_fluid = 10 The temperature-BC for the wall opposite of the surface in the fluid region is a constant value and on the opposing wall in the solid region the gradient is set to a constant value. I uploaded a figure of the temperature distribution after the simulation was run. In the figure, the solid line shows the distribution, yielded from the simulation and the dashed line shows the analytical solution, that should evolve. https://www.dropbox.com/s/rhf42dm0aq..._wall.png?dl=0 The problem is, that the solver doesn't use the harmonic mean (= 1.818) to calculate the heat transfer over the surface but the arithmetic mean (= 5.5). This leads a lower Temperature-gradient between the two cells on each side of the surface, yielding a lower Temperature in the first solid cell. So while the gradient in the solid and fluid field is right, the absolut temperature value isn't. The weird thing is that The DT-field that is saved at the end is actually right, the value at the surface is 1.81 on both sides. So the solver calculates the right value but doesn't use it. I've tried everything mentioned in the older thread and havn't found a solution yet. Thanks for your help in advance! Last edited by gmoehl; February 4, 2015 at 08:47. Reason: forgot to ad the figure

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February 9, 2015, 03:07		#2
gmoehl New Member Join Date: Aug 2012 Posts: 12 Rep Power: 14	Sooo, no one has an idea? has anyone tried out the sover in the new 3.0-extended edition?

February 11, 2015, 09:48		#3
gmoehl New Member Join Date: Aug 2012 Posts: 12 Rep Power: 14	It looks like this problem doesn't occur in the current solver, so I'm gonna work with this one. Nevertheless it would be interesting to know why this error occurs in the older version, so if you know it would be nice if you enlighten me ;-)