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August 26, 2019, 06:46 |
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#41 |
Senior Member
Raza Javed
Join Date: Apr 2019
Location: Germany
Posts: 183
Rep Power: 7 |
This is the output of Code:
wallHeatFlux -region air -latestTime Code:
Wall heat fluxes [W] airTop convective: 0 radiative: 5.796363e-07 total: 5.796363e-07 airLeft convective: 0 radiative: 6.173778e-07 total: 6.173778e-07 airRight convective: 0 radiative: 6.460372e-07 total: 6.460372e-07 airBack convective: 0 radiative: -3.128043e-06 total: -3.128043e-06 airBottom convective: 0 radiative: 6.3663e-07 total: 6.3663e-07 air_to_heater convective: 3.336472e-05 radiative: 6.121647e-07 total: 3.397688e-05 |
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August 26, 2019, 07:13 |
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#42 |
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anonymous
Join Date: Jan 2016
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Yes but your air is steady(all zero velocity), so it is a conduction not a convection (It is like your air is a solid medium). This is why I think your material props are not correct for vacuum. This "concective" flux should be really small, close to zero since there is no media to convect (or conduct) the heat.
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August 26, 2019, 07:26 |
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#43 | |
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Raza Javed
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Location: Germany
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Quote:
I think it is writing convection because in the region properties we declared Air as a Fluid, and normally convection occurs between solid and a fluid. Now, we can be sure that our radiation is working? Below are the results for the same case but without radiation: Code:
Wall heat fluxes [W] airTop convective: 0 radiative: -0 total: 0 airLeft convective: 0 radiative: -0 total: 0 airRight convective: 0 radiative: -0 total: 0 airBack convective: 0 radiative: -0 total: 0 airBottom convective: 0 radiative: -0 total: 0 air_to_heater convective: 3.341257e-05 radiative: -0 total: 3.341257e-05 End |
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August 26, 2019, 08:23 |
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#44 |
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anonymous
Join Date: Jan 2016
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It seems like it's working
I told you to run in both cases because in earlier (i think you are using a never version) versions it only wrote the sum flux (rad+conv) |
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August 26, 2019, 08:33 |
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#45 | |
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Raza Javed
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Location: Germany
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Quote:
Yes I RUN both cases, and I posted here the results of both (with and without radiations). In with radiation, it is showing radiation on every boundary. In withour radiation, it is showing only convection only on air to heater boundary. |
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August 26, 2019, 08:38 |
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#46 |
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anonymous
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I know u did in both cases, I just told you why I gave you this advice.
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August 26, 2019, 08:46 |
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#47 |
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Raza Javed
Join Date: Apr 2019
Location: Germany
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September 1, 2019, 15:01 |
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#48 |
Senior Member
Raza Javed
Join Date: Apr 2019
Location: Germany
Posts: 183
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Hello,
Sorry to disturb you again. In my geometry, I am putting fvOptions in the heater region, the volume of my region is 0.000125m3. And the power I am putting is 1W. So I am using specific mode in fvOptions and I am putting the value 1W/0.000125m3=8000. My fvOptions is given below: Code:
heatSource { type scalarSemiImplicitSource; active true; selectionMode all; scalarSemiImplicitSourceCoeffs { selectionMode all; volumeMode specific;//absolute; injectionRateSuSp { h (8000 0); } } } Now, to check what should be the temperature of my heater region, can I use boltzman law of radiation like below? P = e*sigma*A*(T)^4 |
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May 9, 2022, 13:38 |
thermophysical properties of vaccum
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#49 |
New Member
Patrick Saft
Join Date: May 2022
Posts: 1
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Hello togther,
Raza, i have a similiar problem as you. I also have to calculated vaccum. How do you finally realised it? which thermophysical properties have you taken? thank you kind regards |
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openfoam, radiation, vacuum |
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