Meshing in CHT Problem

Markat · January 8, 2013, 15:24

I try to mesh my geometry (thin plate). The minimum orthogonal quality is about 0.1 and the average about 0.9. The residuals are about 1e-05 after 1000 iterations and can not be further reduced.
Some elements have negative value of wall heat transfer, which I cannot physically explain.
1. Is it important to use inflation or should I ignore inflation to achieve a better minum orthogonal quality?
2.Should I try to use Polyherdal meshing to improve minimum orthogonal quality? Can Polyherdal meshing be used for CHT problems? When I used Polyhedral meshing the maximum value of wall heat transfer was being almost doubled in comparison with Tetrameshing. How could you explain this?

Thank you in advance

Markat · January 10, 2013, 15:56

Could anybody please help me?

Markat · January 13, 2013, 12:36

Does anybody have any idea?

diamondx · January 13, 2013, 12:59

post screenshot of you mesh !! and your geometry !! is it 2d or 3d ?? what software did you use to mesh ??

Markat · January 13, 2013, 13:45

Thnak you for yyour reply! My mesh is 3d and was made in Ansys Mesher (Workbench)

diamondx · January 13, 2013, 13:57

can i see how it looks like

Markat · January 13, 2013, 15:14

I unfortunately don't have an availiable picture of my meshing right now, but I will post one as soon as possible! Thank you in advance for your help

Markat · January 13, 2013, 15:16

Just to imagine it looks like an thin airfoil in a wind tunnel. Only a the fluid was being meshed (I used boolean subtraction to create the appropriate geometry).

diamondx · January 13, 2013, 15:38

it should be easy to mesh with a structured mesh under ICEM are you familiar with icem. when the geometry is easy; always go for a structured mesh if you can.

Markat · January 13, 2013, 15:45

Thank you for your advice! I tried to do a structured mesh! Unfotunately the mesh in the area near the airfoil (cambered) can not be structured.
When I try smoothing the meshing in Fluent I got a better minimum orthogonal quality (~0.4). The simulation result remained unchanged (energy residuals do not ger below 10^-5 so I thought I should try to solve my problem transient)!

January 8, 2013, 15:24	Meshing in CHT Problem	#1
Markat New Member Join Date: Oct 2012 Posts: 27 Rep Power: 13	I try to mesh my geometry (thin plate). The minimum orthogonal quality is about 0.1 and the average about 0.9. The residuals are about 1e-05 after 1000 iterations and can not be further reduced. Some elements have negative value of wall heat transfer, which I cannot physically explain. 1. Is it important to use inflation or should I ignore inflation to achieve a better minum orthogonal quality? 2.Should I try to use Polyherdal meshing to improve minimum orthogonal quality? Can Polyherdal meshing be used for CHT problems? When I used Polyhedral meshing the maximum value of wall heat transfer was being almost doubled in comparison with Tetrameshing. How could you explain this? Thank you in advance

January 13, 2013, 12:59		#4
diamondx Super Moderator Ghazlani M. Ali Join Date: May 2011 Location: Tokyo, Japan Posts: 1,385 Blog Entries: 23 Rep Power: 28	post screenshot of you mesh !! and your geometry !! is it 2d or 3d ?? what software did you use to mesh ?? __________________ Regards, New to ICEM CFD, try this document --> https://goo.gl/KAOIwm Ali

January 13, 2013, 13:57		#6
diamondx Super Moderator Ghazlani M. Ali Join Date: May 2011 Location: Tokyo, Japan Posts: 1,385 Blog Entries: 23 Rep Power: 28	can i see how it looks like __________________ Regards, New to ICEM CFD, try this document --> https://goo.gl/KAOIwm Ali

January 13, 2013, 15:38		#9
diamondx Super Moderator Ghazlani M. Ali Join Date: May 2011 Location: Tokyo, Japan Posts: 1,385 Blog Entries: 23 Rep Power: 28	it should be easy to mesh with a structured mesh under ICEM are you familiar with icem. when the geometry is easy; always go for a structured mesh if you can. __________________ Regards, New to ICEM CFD, try this document --> https://goo.gl/KAOIwm Ali

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January 10, 2013, 15:56		#2
Markat New Member Join Date: Oct 2012 Posts: 27 Rep Power: 13	Could anybody please help me?

January 13, 2013, 12:36		#3
Markat New Member Join Date: Oct 2012 Posts: 27 Rep Power: 13	Does anybody have any idea?

January 13, 2013, 13:45		#5
Markat New Member Join Date: Oct 2012 Posts: 27 Rep Power: 13	Thnak you for yyour reply! My mesh is 3d and was made in Ansys Mesher (Workbench)

January 13, 2013, 15:14		#7
Markat New Member Join Date: Oct 2012 Posts: 27 Rep Power: 13	I unfortunately don't have an availiable picture of my meshing right now, but I will post one as soon as possible! Thank you in advance for your help

January 13, 2013, 15:16		#8
Markat New Member Join Date: Oct 2012 Posts: 27 Rep Power: 13	Just to imagine it looks like an thin airfoil in a wind tunnel. Only a the fluid was being meshed (I used boolean subtraction to create the appropriate geometry).

January 13, 2013, 15:45		#10
Markat New Member Join Date: Oct 2012 Posts: 27 Rep Power: 13	Thank you for your advice! I tried to do a structured mesh! Unfotunately the mesh in the area near the airfoil (cambered) can not be structured. When I try smoothing the meshing in Fluent I got a better minimum orthogonal quality (~0.4). The simulation result remained unchanged (energy residuals do not ger below 10^-5 so I thought I should try to solve my problem transient)!