Need help with 3d mesh - reduce number of cells

stevenbooth · February 19, 2016, 12:54

Hi everyone, I will preface this by saying I am a biologist and very new to CFD.

I have a 3d model of some small airways from a human lung and I am hoping to try and run a CFD of airflow through it to see if any airflow measurements may be different in diseased airways, however I am having some trouble as the model contains too many cells (for the student ver of fluent).

Can anyone explain to me how to reduce the number of cells in the mesh?

Please let me know if you need any additional files or info.

Thanks!
Steve

hwet · February 19, 2016, 20:33

Have you got the geometry file? You need to remesh it obviously...

LuckyTran · February 21, 2016, 13:26

The student version is somewhat limiting in cell count at 512 thousand cells. It's hard to do a high fidelity simulation in complex geometry. It's enough for simple academic models like short straight pipes, but large and complicated domains will inevitably need many more cells to represent to the same degree of accuracy. You should look into getting a full version.

For now, try generating coarse meshes. Cell count goes like dx^3 so simply halving your base cell size reduces your cell count by a factor of 8.

enayath · February 22, 2016, 13:51

I can help you. You may send me your geometry in a private message... meanwhile, try to use coarse mesh size(like 5 mm) and see what you get...To be honest, comment on mesh without knowing the size and the format of the geometry is hard...

Good Luck,
Hooman

jn10hn · February 22, 2016, 14:48

I'm not familiar with the student version of ANSYS but if you have DesignModeler, I sometimes split my geometry using slice and I'm able to control which sections I want to have a finer mesh. Afterwards, you'll have to combine the separate geometries into one model if you want a conformal mesh.

February 19, 2016, 12:54	Need help with 3d mesh - reduce number of cells	#1
stevenbooth New Member Steven Booth Join Date: Feb 2016 Posts: 3 Rep Power: 10	Hi everyone, I will preface this by saying I am a biologist and very new to CFD. I have a 3d model of some small airways from a human lung and I am hoping to try and run a CFD of airflow through it to see if any airflow measurements may be different in diseased airways, however I am having some trouble as the model contains too many cells (for the student ver of fluent). Can anyone explain to me how to reduce the number of cells in the mesh? Please let me know if you need any additional files or info. Thanks! Steve

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February 19, 2016, 20:33		#2
hwet Senior Member Join Date: Mar 2014 Posts: 375 Rep Power: 13	Have you got the geometry file? You need to remesh it obviously...

February 21, 2016, 13:26		#3
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,674 Rep Power: 65	The student version is somewhat limiting in cell count at 512 thousand cells. It's hard to do a high fidelity simulation in complex geometry. It's enough for simple academic models like short straight pipes, but large and complicated domains will inevitably need many more cells to represent to the same degree of accuracy. You should look into getting a full version. For now, try generating coarse meshes. Cell count goes like dx^3 so simply halving your base cell size reduces your cell count by a factor of 8.

February 22, 2016, 13:51		#4
enayath Senior Member Joe Join Date: Feb 2012 Location: Canada Posts: 111 Rep Power: 14	I can help you. You may send me your geometry in a private message... meanwhile, try to use coarse mesh size(like 5 mm) and see what you get...To be honest, comment on mesh without knowing the size and the format of the geometry is hard... Good Luck, Hooman

February 22, 2016, 14:48		#5
jn10hn New Member John C Han Join Date: May 2015 Posts: 4 Rep Power: 10	I'm not familiar with the student version of ANSYS but if you have DesignModeler, I sometimes split my geometry using slice and I'm able to control which sections I want to have a finer mesh. Afterwards, you'll have to combine the separate geometries into one model if you want a conformal mesh.