Conjugate Heat Transfer- Meshing

skapetan · November 10, 2014, 07:14

Hello,

I'm trying to analyze a CHT problem on an exhaust system, but there just some meshing facts where I'm not sure about how to handle it. So I wanted to discuss that issues with you and get your help.

-my case consist of a small solid region ( 4mm thickness )

It's clear that I need a Solid and a Fluid Region to setup CHT (+Interface between Regions). I wonder how to mesh this regions. For an accurate solution its recommended to have a conformal mesh between Fluid and Solid.

First option is to generate one mesh continuum and second option is to generate two mesh continua for each region.

So is it possible to achieve a conformal mesh via an contact interface if I chose option two?

The reason why I want to mesh with two continua is because of my thin Solid Region. Therefor I want to use the Thin mesher.

What do you recommend for my case? Is it useful to use the Thin mesher? Or should I mesh with 1 continuum and costumize my Poly-mesh in the Solid region?

Thanks for you help.

kguntur · November 11, 2014, 01:53

Hi,

You can get a conformal mesh using a single mesh continuum. Using one mesh continuum for multiple regions is compatible only for polyhedral mesh. So use that along with embedded thin mesher and you can get a conformal interface. Make sure you have created the interface before meshing.

However, if you want to use trimmer for the fluid region, then surface mesh the solid and fluid regions together and then generate the volume mesh. This will not give you a conformal interface, but it will give almost 100% interface.

Hope this helps.

Bust · November 12, 2014, 04:35

Hi,

As kguntur said: 1 continuum and the Embedded Thin mesher should be the way to go.

I did exactly the same once and a there are basically no restrictions. Remember to turn on the "grow prism layer" option for your interfaces, you can then deactivate the prism layers again in the solid region.

Cheers!

skapetan · November 18, 2014, 07:58

Thank you for your fast response.

Is there any option where I can check if i have a conformal mesh or not?

Basically it would be possible to use the two mesh continuum with the consequence being a bad accuracy for my solution or no convergence, is that right?

kguntur · November 18, 2014, 08:15

Once you create your interfaces and generate the volume mesh, right click the interface and click initialize. If it is a conformal match, you should be able to see that in the output window.

Two mesh continuum will not give conformal mesh. It is not all bad. I have used that successfully for many simulations. However, conformal mesh has fewer errors.

skapetan · November 19, 2014, 05:23

Thanks a lot for this very helpful informations.

skapetan · November 20, 2014, 09:17

I disabled prism layers at the solid region and activated "Grow Prisms from Interface" at the Interface Prism layer Option.

If you take a look at this picture 3D plane.jpg you can see that prism layer are only generated in the Fluid Region of the Ribed channel.

What I'm wondering about is if there should be prism layers at the wall of my channel and around the ribs if I convert my mesh into a 2D mesh. As you can see here there are no visible prism layer around the ribs etc. 2D Mesh.jpg .

Do I have to change some options for my 2D mesh?

Thanks in advance.

November 10, 2014, 07:14	Conjugate Heat Transfer- Meshing	#1
skapetan New Member Join Date: Apr 2014 Posts: 24 Rep Power: 12	Hello, I'm trying to analyze a CHT problem on an exhaust system, but there just some meshing facts where I'm not sure about how to handle it. So I wanted to discuss that issues with you and get your help. -my case consist of a small solid region ( 4mm thickness ) It's clear that I need a Solid and a Fluid Region to setup CHT (+Interface between Regions). I wonder how to mesh this regions. For an accurate solution its recommended to have a conformal mesh between Fluid and Solid. First option is to generate one mesh continuum and second option is to generate two mesh continua for each region. So is it possible to achieve a conformal mesh via an contact interface if I chose option two? The reason why I want to mesh with two continua is because of my thin Solid Region. Therefor I want to use the Thin mesher. What do you recommend for my case? Is it useful to use the Thin mesher? Or should I mesh with 1 continuum and costumize my Poly-mesh in the Solid region? Thanks for you help.

November 11, 2014, 01:53		#2
kguntur Member kris Join Date: May 2014 Posts: 73 Rep Power: 11	Hi, You can get a conformal mesh using a single mesh continuum. Using one mesh continuum for multiple regions is compatible only for polyhedral mesh. So use that along with embedded thin mesher and you can get a conformal interface. Make sure you have created the interface before meshing. However, if you want to use trimmer for the fluid region, then surface mesh the solid and fluid regions together and then generate the volume mesh. This will not give you a conformal interface, but it will give almost 100% interface. Hope this helps. skapetan likes this.

November 12, 2014, 04:35		#3
Bust New Member Bastian N. Join Date: Jul 2014 Posts: 6 Rep Power: 11	Hi, As kguntur said: 1 continuum and the Embedded Thin mesher should be the way to go. I did exactly the same once and a there are basically no restrictions. Remember to turn on the "grow prism layer" option for your interfaces, you can then deactivate the prism layers again in the solid region. Cheers! skapetan likes this. Last edited by Bust; November 13, 2014 at 09:11.

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November 18, 2014, 07:58		#4
skapetan New Member Join Date: Apr 2014 Posts: 24 Rep Power: 12	Thank you for your fast response. Is there any option where I can check if i have a conformal mesh or not? Basically it would be possible to use the two mesh continuum with the consequence being a bad accuracy for my solution or no convergence, is that right?

November 18, 2014, 08:15		#5
kguntur Member kris Join Date: May 2014 Posts: 73 Rep Power: 11	Once you create your interfaces and generate the volume mesh, right click the interface and click initialize. If it is a conformal match, you should be able to see that in the output window. Two mesh continuum will not give conformal mesh. It is not all bad. I have used that successfully for many simulations. However, conformal mesh has fewer errors.

November 19, 2014, 05:23		#6
skapetan New Member Join Date: Apr 2014 Posts: 24 Rep Power: 12	Thanks a lot for this very helpful informations.

November 20, 2014, 09:17		#7
skapetan New Member Join Date: Apr 2014 Posts: 24 Rep Power: 12	I disabled prism layers at the solid region and activated "Grow Prisms from Interface" at the Interface Prism layer Option. If you take a look at this picture 3D plane.jpg you can see that prism layer are only generated in the Fluid Region of the Ribed channel. What I'm wondering about is if there should be prism layers at the wall of my channel and around the ribs if I convert my mesh into a 2D mesh. As you can see here there are no visible prism layer around the ribs etc. 2D Mesh.jpg . Do I have to change some options for my 2D mesh? Thanks in advance.