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|ID||Project||Category||View Status||Date Submitted||Last Update|
|0003927||OpenFOAM||Bug||public||2022-11-04 11:35||2022-11-04 21:43|
|Reporter||Lukasz Bazydlo||Assigned To||henry|
|Status||closed||Resolution||no change required|
|Summary||0003927: chtMultiRegionFoam - results seem wrong when using constAnIsoSolid in cylindrical coordinates|
|Description||A hollow cylinder body with a heat flux of 1000 W/m2 specified at the inner radius wall and constant temperature of 300 K at the outer radius wall, all other walls zeroGradient. Thermal conductivity is specified using constAnIsoSolid as (1.3 28 28) in the cylindrical coordinate system, the rest of the material properties are constant. The obtained results do not match the analytical solution and exactly the same set-up in ANSYS Fluent. The radial component of conductivity seems overestimated ~2 times. Also there is a discrepancy between results obtained using kappa (1.3 28 28) and isotropic kappa 1.3, which should be the same considering that side walls are insulated so axial and angular components should not matter (described behaviour can be observed while using Fluent).|
The issue seems like a strange behaviour of the anisotropic material model, also the documentation/built-in tutorials seem to lack information about the topic.
|Steps To Reproduce||1. Run the attached case|
2. In file constant/solid/physicalProperties change entry mixture/transport/kappa to value (1.3 1.3 1.3)
in file constant/solid/physicalProperties change entry thermoType/transport to value constIsoSolid and entry mixture/transport/kappa to 1.3
3. Compare both results
|Additional Information||Inner radius wall temperatures obtained by analytical calculations and Fluent/OpenFOAM:|
- Analytical - T_inner = 308.86 K
- Fluent cylindrical aniso (1.3 28 28) - T_inner = 308.81 K
- Fluent iso 1.3 - T_inner = 308.81 K
- OpenFOAM cylindrical aniso (1.3 28 28) - T_inner = 304.84 K
- OpenFOAM cylindrical aniso (1.3 1.3 1.3) - T_inner = 308.46 K
- OpenFOAM iso 1.3 - T_inner = 308.46 K
Based on obtained temperature value in case of OpenFOAM cylindrical aniso (1.3 28 28), the effective radial kappa is 2.38 W/mK
|Tags||No tags attached.|
The handling of anisotropic thermal conductivity is incomplete in OpenFOAM-10 and before, it assumes alignment with the boundary. I have recently completed a rewrite of the entire solid energy transport in OpenFOAM-dev which might/should resolve this issue:
Author: Henry Weller <http://cfd.direct>
Date: Mon Oct 24 19:01:52 2022 +0100
solidThermophysicalTransportModel::anisotropic: Added heat-flux correction qCorr
to handle the wall heat-flux generated by the tangential components of the
temperature gradient when the thermal conductivity tensor Kappa does not align
with the boundary. This is an uncommon situation but for cases where it is
important it must be handled correctly; previously this term was ignored.
For efficiency the temperature gradient field is automatically cached so that it
is not evaluated for every patch for which Kappa is not aligned with the
boundary, and the correction is evaluated and applied only for those patches.
The heat-flux correction qCorr is used in the coupled and external heat-flux
boundary conditions coupledTemperature and externalTemperature.
||You will need to check very carefully the setup of the coordinate system, it looks like from your results that the first component of kappa is not in the radial direction. In the OpenFOAM-dev implementation you can write out the Kappa tensor field and study it.|
I could not unpack the test-case, RAR is not a standard Linux compression format.
Try your case with (28 1.3 28) and (28 28 1.3)
Sorry, I have uploaded the case in .tar.gz format now. Regarding your suggestions:
- I have already tried running the case with (28 1.3 28) and (28 28 1.3) using OpenFOAM 10. Tried the same approach again with OpenFOAM-dev and uploaded the comparison of the results. The behaviour in OpenFOAM-dev is different - all the results were the same. Also, I have tried to use (1.3 0.1 0.1) with OpenFOAM-dev and got max temp equal to 308.44 K, which is close to the value obtained using isotropic properties.
- I have run the same case using freshly installed OpenFOAM-dev - the inner radius temperature decreased to 300.279 K.
- I don't know how to get a kappa tensor using OpenFOAM-dev but I managed to obtain a KappaLocal tensor from OpenFOAM 10 using the debugger. The values were KappaLocal = 9.73,  = 12.41,  = 0,  = 19.57,  = 0,  = 28. I presume that this is just an example value for 1 point, but I hope it might help.
test_anisotropic_conduction.tar.gz (2,073,252 bytes)
I set the case up in dev, reorganising as a solid only case running with
foamRun -solver solid
setting the coordinate system in thermophysicalTransport
origin (0 0 0);
axis (0 0 1);
and used a more accurate grad scheme because of the horrible tet-mesh:
and I get the same results for
constIsoSolid with kappa 1.3
constAnIsoSolid with kappa (28 28 28)
constAnIsoSolid with kappa (1.3 28 28)
There is no bug, this is a user-support request, if you need further assistance you will need to arrange for a support contract.
User error and support request.
|2022-11-04 11:35||Lukasz Bazydlo||New Issue|
|2022-11-04 11:35||Lukasz Bazydlo||File Added: test_anisotropic_conduction.rar|
|2022-11-04 11:35||Lukasz Bazydlo||File Added: model_scheme.PNG|
|2022-11-04 11:35||Lukasz Bazydlo||File Added: comparison.png|
|2022-11-04 11:35||Lukasz Bazydlo||File Added: comparison2.PNG|
|2022-11-04 12:18||henry||Note Added: 0012855|
|2022-11-04 12:26||henry||Note Added: 0012856|
|2022-11-04 18:55||henry||File Deleted: test_anisotropic_conduction.rar|
|2022-11-04 18:57||henry||Note Added: 0012857|
|2022-11-04 20:49||Lukasz Bazydlo||Note Added: 0012858|
|2022-11-04 20:49||Lukasz Bazydlo||File Added: comparison_10_vs_dev.PNG|
|2022-11-04 20:49||Lukasz Bazydlo||File Added: OpenFOAM-dev_1.3-0.1-0.1.PNG|
|2022-11-04 20:49||Lukasz Bazydlo||File Added: test_anisotropic_conduction.tar.gz|
|2022-11-04 21:43||henry||Note Added: 0012859|
|2022-11-04 21:43||henry||Assigned To||=> henry|
|2022-11-04 21:43||henry||Status||new => closed|
|2022-11-04 21:43||henry||Resolution||open => no change required|
|2022-11-04 21:43||henry||Note Added: 0012860|