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How to clip the critical radius in non-equilibrium condensation model with a CEL? |
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October 25, 2018, 11:15 |
How to clip the critical radius in non-equilibrium condensation model with a CEL?
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#1 |
New Member
Zhiyuan Liu
Join Date: Oct 2018
Location: China
Posts: 26
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I am troubled in the simulation of supercritical CO2 non-equilibrium condensation.
I have tried my best to make it converge. However, it doesn't work. I have reduced the time step to 10^-8s, adopted the double precision calculation, and used the single-phase converged result as the initial field. An article mentioned a trick to clip the critical radius of droplet. I'm wondering how to clip the critical radius with a CEL? It's an output parameter, so I'm confused. Last edited by Saeef; October 26, 2018 at 08:44. Reason: supplement |
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October 25, 2018, 17:43 |
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#2 |
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Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
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First of all look at the FAQ on floating point error: https://www.cfd-online.com/Wiki/Ansy...do_about_it.3F
Assuming the simulation is set up correctly the best way to increase your numerical stability is to improve your mesh quality. This can make a huge difference in difficult material models like yours. I would put off fiddling with factors like the critical radius for now - your problem is likely to be more fundamental than that.
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October 26, 2018, 02:11 |
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#3 |
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Hello,
I am the corresponding author of that paper you have mentioned. Yes, we have to write couple of CEL functios to force the solver to change the critical radius limits. But in your case, the divergence is not becase of the critical radius. As far as I remember, we could get converged results, but the droplet size was non-realistic. can you explain more abour your case, boundary consitions and other stuff. In parallel I try to find the CFDX file for that simulation to give you the CEL functions which we wrote. Good luck. |
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October 26, 2018, 08:49 |
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#4 | |
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Zhiyuan Liu
Join Date: Oct 2018
Location: China
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Quote:
Since I have obtained converged result with single-phase simulation, I think the mesh quality should be sufficient. Thank you for your advice. Best regards, Saeef |
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October 26, 2018, 09:34 |
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#5 | |
New Member
Zhiyuan Liu
Join Date: Oct 2018
Location: China
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Quote:
That's really a coincidence. I didn't expect you were in this forum. I have just started the research of SCO2 non-equilibrium condensation. The first study case is the Laval nozzle which you have calculated. The detail of my settings in CFX-Pre was attached here and the .rgp files were generated by my own matlab codes. It referred to the steam turbine case in CFX tutorial. My email address: liuzhiyuan@iet.cn Appreciate your help. Best regards, Saeef |
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October 26, 2018, 20:42 |
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#6 | |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
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Quote:
When you are having troubles with convergence improving mesh quality ALWAYS helps, and sometimes completely fixes the problem. Mesh quality is often underestimated by inexperienced CFD people.
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July 10, 2021, 00:50 |
sCO2 condensation CFX model
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#7 | |
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MD Shujan Ali
Join Date: Jul 2021
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Quote:
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July 10, 2021, 00:53 |
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#8 | |
New Member
MD Shujan Ali
Join Date: Jul 2021
Posts: 2
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Quote:
I am also working with sCO2 condensation inside de Laval nozzle. Please can you send me your CFX File or CCL File? It would be a great favor if you can share your files. My email md_shujan@tamu.edu Best regards, MD Shujan Ali |
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September 27, 2021, 23:39 |
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#9 | |
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橡皮擦
Join Date: Apr 2018
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Quote:
Have you solved the critical radius clip problem? May you share us how to write the CEL to clip the critical radius? My email address is xupengcheng@buaa.edu.cn Many thanks! Best regards |
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Tags |
condensation model, supercrical co2 |
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