Dissimilar meshes with chtMultiRegionFoam

crmccreary · September 19, 2011, 21:51

I've been using chtMultiRegionFoam with good success for some time now. To date, all of the cases I've solved have been "consistent" meshes in that the solid/fluid interface patches share the same points. Is there a mechanism in OpenFOAM in which I can use completely different meshes for the solid and the fluid in which no points are shared?

My objective is to have a rather coarse mesh for the solid and a very fine mesh for the surrounding fluid.

mabinty · September 21, 2011, 03:03

thats a very good question I d be also interested in! what I m currently trying is to refine the base mesh where later on the individual regions should be placed in order to achieve different mesh sizes in the regions.

aram

vkrastev · September 21, 2011, 08:34

The chtMultiRegionFoam (and chtMultiRegionSimpleFoam as well) solver implemented in the OpenCFD OpenFOAM releases (at least till the 1.7.1 one) needs a consistent mesh at the separation surface between different regions. By the way, I saw recently a presentation from Prof. Jasak in which he explained quite clearly that the GGI (Generic Grid Interface) implemented in the -dev or -ext OpenFOAM releases is (in principle) capable of handling any type of flux exchange between two adiacent non-conformal interfaces: thus, if you are interested in this topic, I can advice you to deeply investigate the capabilities of the OpenFOAM-1.6-ext release (personally I havent't had sufficient time to do it in the last period, so I will not be able to give you any practical further support about this matter).

Regards

V.

chandramurthy · September 21, 2011, 15:02

It must be possible with ggi feature of 1.6-ext. The non-conformal fluid-solid coupled BC need to be conservative and at-least 2nd order accurate to get better results. I think it can work out, if you can write a new BC inheriting the classes of ggi and coupled bc of chtmultiregionfoam. It appears that the present implementation of ggi in 1.6-ext is conservative due to face-cutting method. I think it is possible to implement it.
I have done a similar type work, which takes the nearest 3 points and calculates new face field using inverse distance weight function method. hope this is useful
regards,
Chandra Murthy

tjliang · February 9, 2016, 06:49

Hello,

Could anyone tell me if it is possible to use dynamic mesh refinement in fluid region in chtmultiregionfoam . If yes, could someone tell me how.

Bests ,

Peng

hcl734 · February 12, 2016, 03:26

I don't know about dynamic mesh refinement but to answer the original question of this thread.
It is possible to use arbitrary mesh interfaces by using nearestPatchFaceAMI as boundary type between solid and fluid.

hcl734 · February 12, 2016, 04:07

Also take a look at this

http://www.cfd-online.com/Forums/ope...-openfoam.html

September 19, 2011, 21:51	Dissimilar meshes with chtMultiRegionFoam	#1
crmccreary New Member Charles McCreary Join Date: Jun 2010 Posts: 12 Rep Power: 15	I've been using chtMultiRegionFoam with good success for some time now. To date, all of the cases I've solved have been "consistent" meshes in that the solid/fluid interface patches share the same points. Is there a mechanism in OpenFOAM in which I can use completely different meshes for the solid and the fluid in which no points are shared? My objective is to have a rather coarse mesh for the solid and a very fine mesh for the surrounding fluid.

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September 21, 2011, 03:03		#2
mabinty Senior Member Aram Amouzandeh Join Date: Mar 2009 Location: Vienna, Vienna, Austria Posts: 190 Rep Power: 17	thats a very good question I d be also interested in! what I m currently trying is to refine the base mesh where later on the individual regions should be placed in order to achieve different mesh sizes in the regions. aram

September 21, 2011, 08:34		#3
vkrastev Senior Member Vesselin Krastev Join Date: Jan 2010 Location: University of Tor Vergata, Rome Posts: 368 Rep Power: 20	The chtMultiRegionFoam (and chtMultiRegionSimpleFoam as well) solver implemented in the OpenCFD OpenFOAM releases (at least till the 1.7.1 one) needs a consistent mesh at the separation surface between different regions. By the way, I saw recently a presentation from Prof. Jasak in which he explained quite clearly that the GGI (Generic Grid Interface) implemented in the -dev or -ext OpenFOAM releases is (in principle) capable of handling any type of flux exchange between two adiacent non-conformal interfaces: thus, if you are interested in this topic, I can advice you to deeply investigate the capabilities of the OpenFOAM-1.6-ext release (personally I havent't had sufficient time to do it in the last period, so I will not be able to give you any practical further support about this matter). Regards V.

September 21, 2011, 15:02		#4
chandramurthy Member MSR CHANDRA MURTHY Join Date: Mar 2009 Posts: 33 Rep Power: 17	It must be possible with ggi feature of 1.6-ext. The non-conformal fluid-solid coupled BC need to be conservative and at-least 2nd order accurate to get better results. I think it can work out, if you can write a new BC inheriting the classes of ggi and coupled bc of chtmultiregionfoam. It appears that the present implementation of ggi in 1.6-ext is conservative due to face-cutting method. I think it is possible to implement it. I have done a similar type work, which takes the nearest 3 points and calculates new face field using inverse distance weight function method. hope this is useful regards, Chandra Murthy

February 9, 2016, 06:49		#5
tjliang Member Peng Liang Join Date: Mar 2014 Posts: 59 Rep Power: 12	Hello, Could anyone tell me if it is possible to use dynamic mesh refinement in fluid region in chtmultiregionfoam . If yes, could someone tell me how. Bests , Peng

February 12, 2016, 03:26		#6
hcl734 Member Join Date: May 2015 Posts: 68 Rep Power: 10	I don't know about dynamic mesh refinement but to answer the original question of this thread. It is possible to use arbitrary mesh interfaces by using nearestPatchFaceAMI as boundary type between solid and fluid.

February 12, 2016, 04:07		#7
hcl734 Member Join Date: May 2015 Posts: 68 Rep Power: 10	Also take a look at this http://www.cfd-online.com/Forums/ope...-openfoam.html