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#1 |
Senior Member
Weiqiang Liu
Join Date: Feb 2018
Posts: 278
Rep Power: 9 ![]() |
Hi all,
I am doing a methane combustion simulation with fluent. I followed the node distribution in literature and drew the same mesh with the author. Because the geometry is a very thin channel, the final mesh has very large aspect ratio with maximum aspect ratio 150. I used this mesh to continue my simulation. Divergence did not happen with this mesh. However, I can not ignite the mixture like the author did. Temperature would increase to a high temperature and then drop to room temperature. I am wondering could this mesh with high aspect ratio be the reason why I can not ignite the mixture? will large aspect ratio mesh effect results accuracy? Can somebody who has combustion simulation experience give me some suggestions? Best regards Weiqiang |
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#2 |
Senior Member
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The effect that you observed cannot be because of mesh. AR 150 is an order of magnitude smaller than what is used in boundary layers for high speed flows. So, this will not affect the physics they way your are observing. Either there is some heat loss or the parameters given for the reaction kinetics (provided you are using finite rates) are incorrect. Check material properties as well.
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Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority. |
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#3 | |
Senior Member
Weiqiang Liu
Join Date: Feb 2018
Posts: 278
Rep Power: 9 ![]() |
Quote:
All chemical kinetics, thermal and transport are imported into fluent with CHEMKIN files. Actually my gas phase mechanism is different with the author's. Mine is simpler due to the limitation of computation power. I tried to keep other settings the same with the author. Do you think will the difference of gas mechanism cause ignition failure? Thank you Weiqiang |
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#4 |
Senior Member
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If it is a reduced mechanism then it has to be done carefully. Chemical mechanism reduction is a field of study in itself. I'd suggest you to try with elemental reactions before using detailed kinetics.
__________________
Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority. |
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#5 | |
Senior Member
Weiqiang Liu
Join Date: Feb 2018
Posts: 278
Rep Power: 9 ![]() |
Quote:
Best weiqiang |
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Tags |
accuracy, aspect ratio, combustion, convergence |
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