finer mesh never achieved convergence of total energy

ngonbadipoor@yahoo.com · January 6, 2017, 04:26

Hi
I am modeling a 3 D laminar flow in a pipe with constant Heat flux (H2). to check the converging situation I choose several items .e.g. on a created point I select a surface-monitoring of vertex average of total energy . when running a convergence history for finest mesh never achieved while for coarser mesh had achieved before. I will be glad to know why?
thanks

LuckyTran · January 6, 2017, 10:55

Check your mesh quality. Fine meshes generally have higher potential for greater # of skewed cells (since there is an overall greater number of total cells). Skewed cells will mess things up.

Fine meshes converge slower than coarse meshes.
Fine meshes are inherently more unstable than coarse meshes (because there is less numerical dissipation).

The finer your mesh, the greater the importance of it needing to be high quality.

ngonbadipoor@yahoo.com · January 7, 2017, 01:35

thanks LuckyTran
I attached the mesh metric. please let me know what you think
thanks
[IMG]file:///C:/Users/navid/AppData/Roaming/Ansys/v160/preview.png[/IMG]

January 6, 2017, 04:26	finer mesh never achieved convergence of total energy	#1
ngonbadipoor@yahoo.com Member NGP Join Date: Mar 2016 Posts: 33 Rep Power: 10	Hi I am modeling a 3 D laminar flow in a pipe with constant Heat flux (H2). to check the converging situation I choose several items .e.g. on a created point I select a surface-monitoring of vertex average of total energy . when running a convergence history for finest mesh never achieved while for coarser mesh had achieved before. I will be glad to know why? thanks

January 6, 2017, 10:55		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,675 Rep Power: 66	Check your mesh quality. Fine meshes generally have higher potential for greater # of skewed cells (since there is an overall greater number of total cells). Skewed cells will mess things up. Fine meshes converge slower than coarse meshes. Fine meshes are inherently more unstable than coarse meshes (because there is less numerical dissipation). The finer your mesh, the greater the importance of it needing to be high quality. ngonbadipoor@yahoo.com likes this.

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