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Phase depending absorption & emission model properties |
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#1 | |
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Hektor
Join Date: Feb 2020
Posts: 5
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Hello,
I am trying to model laser melting using OpenFOAM1912, with the icoReactingMultiphaseInterFoam solver. This solver has the radiation model laserDTRM built in. I have managed to solve simple problems nicely, but the optical properties are significantly different in the gas (almost completely transmissive)/liquid(highly absorbing)/solid phases(highly absorbing and reflective). Is it possible to set the absorptivity/emissivity/E to different values in different phases? Does any of the built in models support this? I have tried looking around in the source code, but I do not quite follow the radiation models. Any help on the topic is greatly appreciated. EDIT: It seems that localDensityAbsorptionEmission does the trick, and it does more or less what I would expect. Best regards Hektor Attachments: radiationProperties Code:
radiation on; radiationModel laserDTRM; solverFreq 3; absorptionEmissionModel constantAbsorptionEmission; mode "Gaussian"; nTheta 20; nr 100; opd 0.4425; focalLaserPosition constant (.0002 .00020 0.0002); laserDirection constant (0 -1 0); focalLaserRadius 0.000025; laserPower 200; sigma 25e-6; //qualityBeamLaser 1.0; absorptivity absorptivity [0 -1 0 0 0 0 0] 1e5; emissivity emissivity [0 -1 0 0 0 0 0] 0.04; E E [1 -1 -3 0 0 0 0] 0; scatterModel none; sootModel none; transmissivityModel none; Quote:
Last edited by hektorWartgard; February 12, 2020 at 08:25. Reason: Found solution |
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#2 |
New Member
Bill
Join Date: Jun 2019
Posts: 29
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Hi Hektor,
I am also trying to work with LaserDTRM for laser melting. Unfortunately, I don't know much about your problem, but I wonder if it is connected to a problem I am having. I also have three phases set up (gas, liquid, solid), however, the laser source will not travel through the gas phase and into the solid phase. I have attached quick snapshots from paraview. I use a simple blockmesh and then initialize the phases using setFields. Have you also encountered this problem? Cheers |
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#3 |
New Member
Hektor
Join Date: Feb 2020
Posts: 5
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My solution has been to use the "localDensityAbsorptionEmission" absorption/emission model, there you can set the absorptivity/emissivity/E of the different phases.
The value can be set to 0 for the gas, and metals typically have around 10^8 1/m. Find good values for your material at (https://refractiveindex.info/). The other option is to to skip the gas phase and use a boundary condition to model the laser. This will work if you have a high absorptivity and a simple geometry. |
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#4 |
New Member
Bill
Join Date: Jun 2019
Posts: 29
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Hi Hektor,
Thanks for your quick reply. I'm glad you were able to figure your problem out. I'm trying to incorporate your comments, but I don't know how exactly to code in the coefficients. Here's what I have: localDensityAbsorptionEmissionCoeffs { alphaNames alpha.gas; absorptivity absorptivity [0 -1 0 0 0 0 0] 0; emissivity emissivity [0 -1 0 0 0 0 0] 0; E E [1 -1 -3 0 0 0 0] 0; alphaNames alpha.liquid; absorptivity absorptivity [0 -1 0 0 0 0 0] 0; emissivity emissivity [0 -1 0 0 0 0 0] 0; E E [1 -1 -3 0 0 0 0] 0; alphaNames alpha.solid; absorptivity absorptivity [0 -1 0 0 0 0 0] 0; emissivity emissivity [0 -1 0 0 0 0 0] 0; E E [1 -1 -3 0 0 0 0] 0; } Any insight? Thanks in advance! |
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#5 |
New Member
Bill
Join Date: Jun 2019
Posts: 29
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I think I was able to figure it out after trial and error. For anyone else interested, here's what ended up working for me:
localDensityAbsorptionEmissionCoeffs { alphaNames (alpha.gas alpha.liquid alpha.solid); aCoeff (0 1e3 1e10); eCoeff (0 0.5 0.5); ECoeff (0 0.5 0.5); } Please let me know if I made any errors or left something out. Thanks! |
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#6 |
New Member
Hektor
Join Date: Feb 2020
Posts: 5
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Yes this looks correct.
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Tags |
laser melting, phase change material, radiation model |
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