|
[Sponsors] |
explanation about radiation model coefficients |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
December 14, 2023, 12:18 |
explanation about radiation model coefficients
|
#1 |
New Member
nicolas Claverie
Join Date: Sep 2022
Posts: 3
Rep Power: 4 |
Hello !
Stupid question: What is the physical definition of the coefficient of the radiation model constantAbsorptionEmission : (for example in the multiRegionHeaterRadiation tutorial) constantAbsorptionEmissionCoeffs { absorptivity absorptivity [0 -1 0 0 0 0 0] 0.0; //opaque emissivity emissivity [0 -1 0 0 0 0 0] 0.1; E E [1 -1 -3 0 0 0 0] 0; } They can’t be the absorption and emission coefficient of the material since they are in [1/meter] units. Also, people online recommend values as high as 1e8 for them in some cases but the coefficient i know should be between 0 and 1. E is apparently the emission contribution but I see no physical equivalent for this. How can I find those value for a specific material (like aluminum for example). PS: install information if relevant: Windows 11 pro 22H2 WSL 2.0.9.0 Ubuntu 22.04.3 LTS Openfoam 2306 |
|
December 15, 2023, 04:25 |
|
#2 |
Senior Member
Join Date: Dec 2021
Posts: 231
Rep Power: 5 |
Hey,
I have been struggling too with this! As far as I know, these values are indeed different from the absorptivity and emissivity of surfaces which are between 0 and 1 as you said. I believe they are the absorption and emission coefficients which can be really high for opaque solids. It basically tells you how much energy from a beam will be dissipated/scattered as it goes through the medium. For non participating medium, these values should be near 0, meaning the radiation goes through unhampered. For opaque solids, you should just set the radiation model to opaqueSolid, and let your boundaryRadiationProperties take care of the heat transfer, the coefficients don't matter. And if you have semi-transparent media, you are out of luck because OpenFoam does not support it currently. Hope it helps though! |
|
December 15, 2023, 11:25 |
|
#3 |
New Member
nicolas Claverie
Join Date: Sep 2022
Posts: 3
Rep Power: 4 |
Thanks a lot for your answer! Any idea what E is supposed to be?
|
|
Tags |
coefficients, definition, radiation, unit |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
radiation model DO "edge effect" | JMM_UC3M | FLUENT | 0 | November 22, 2021 01:23 |
S2S Radiation Model at non conformal interfaces | ataoulalim | FLUENT | 4 | May 31, 2017 13:38 |
Overflow Error in Multiphase Modelling with Two Continuous Fluids | ashtonJ | CFX | 6 | August 11, 2014 14:32 |
GETVAR Error in Multiband Monte Carlo Radiation Simulation with Directional Source | silvan | CFX | 3 | June 16, 2014 09:49 |
Selecting the appropriate multiphase model and radiation model | panos_metal | FLUENT | 0 | June 18, 2010 07:58 |