CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   FLUENT (http://www.cfd-online.com/Forums/fluent/)
-   -   Connecting two fluid zones in Ansys Fluent 12 (http://www.cfd-online.com/Forums/fluent/72873-connecting-two-fluid-zones-ansys-fluent-12-a.html)

izumi11 February 20, 2010 02:46

Connecting two fluid zones in Ansys Fluent 12
 
Hello,
I have been struggling for awhile with this. My geometry is made of several fluid zones which are supposed to be connected. When I mesh with ansys, it creates walls and interior boundaries. I would like to remove the walls, but it seems I can't. Also I cannot change a wall b.c. into interior for some reason.
Your help is greatly appreciated.

izumi11 February 20, 2010 03:04

Also Ansys mesher computes all the contacts between bodies before creating the mesh, but this doesn't translate into interface b.c. I think one way to make it work would be to create named selections on each faces that are connected and defined them later as interface, but this takes a lot of work and there should be a way to do this automatically in my opinion.
Thanks in advance for the help ^^

msen February 23, 2010 01:12

What are your inlet conditions and how did you define your inlet geometry? You should be able to define an inlet boundary condition for each different fluid at the inlet. You do not have to connect them in this case.

izumi11 February 23, 2010 07:13

Hi thank you for your reply. My fluid is as follows :
-two inlets, one with hydrogen+h2o, one with air
-one outlet.
For the moment I am only interested in the flow so I am ok with a single species, single phase simulation.

The problem is I have spread the fluid into several different contiguous zones. Some of which are porous. Therefore I can't merge them at the cad level. Ansys should handle it. So the outlet and the inlets are in different zones.

What I get is the interface between inlet and outlet becomes a wall under Fluent and the continuity residual never decreases as a result (obviously) because the fluid can't escape.
There should be a way to automate this process. I can't prescribe every fluid interface since there is a large number of zones. I know that the mesher in workbench resolves contacts, but it seems it creates wall b.c. where it should be an interface. Is there a way to tell ansys that a contact between two fluids should be an interface whereas a contact between a fluid and a solid should be a wall?

Hope I was clear enough.
Thanks

izumi11 February 24, 2010 10:31

Ok I think I get the problem. From the fluent perspective I should use fuse faces to merge the walls. Fluent will then create a new thread for the intersecting faces and I can set it to interior. The problem is fluent calculates face coincidence on a node by node basis, which means only conformal interfaces are merged. In my case faces were merged separately so this doesn't work.

I think there is a way in designmodeler to let the mesher know it should mesh contacting faces together, by using "shared topology". I couldn't get it to work though.

A third solution would be I guess to use virtual topologies in the mesher, but I am not sure that will work.
What's bothering me is that Ansys mechanical goes all the way to calculate every contact, but doesn't apply that to meshing fluid interfaces. I think the information is only used for mechanical contacts or FSI.

anga87610del March 25, 2010 01:24

2 fluids at different inlets
 
Sir, I am facing problem in having 2 different fluids at 2 inlets at different sections of my geometry(liquid water and air)fluent only shows an option for mixture ,is there any way out to specify these 2 liquids differently at the two inlets.I hope i have made my point clearly.

izumi11 March 25, 2010 02:18

My problem was only about connecting the fluid zones in the mesher. In ansys I've solved it by using multi-body parts. I think your problem is different. I think you will need to do a multiphase simulation with some kind of interface tracking unless the liquids don't mix. Since I only use gases I only had to set the percentage of each species at each inlet so a simple mixture simulation was enough.
Hope that helps.

anga87610del March 25, 2010 02:53

actually i only want know ..how u set different fluid at each inlet(as u may have done in ur case)...in multiphase it only gives phases to be set..how to set specific fluid at specific inlet...please help me out with procedure in ansys fluent ver. 6.3...as u may have done it in ur case.

Thanks:)

izumi11 March 25, 2010 03:11

In my case it's a gas mixture so there is only one phase. I set the inlet as a mass flow inlet. In materials, I set the fluid as a mix of hydrogen, oxygen h2o and nitrogen. The in the inlet bc, species tab, I set hydrogen mass fraction to 1 for inlet 1 and oxygen mass fraction to 0.21 for inlet 2.
Now this is only a gas mix so it is not really multiphase, in your case since liquids are involved it might be more complicated.
best.

anga87610del March 25, 2010 03:47

thanx..!!!!

sammyraj May 14, 2010 23:14

2 fluids at different inlets
 
Hi

I am facing same problem as anga87610del, I have to introduce two fluids( liquids) at two inlets and the geometry consists of two annular pipes in which inside pipes ends at the middle and fluid coming from it joins with the fluid coming from outside pipe and both go through a single outlet. Hope I made it clear.

Please suggest me a method to use and how to introduce two inlets especially and I have been trying to use VOF method but I am not sure I am in a correct way. and also my fluids does not mix.

anga87610del please let me know if you have found solution.


Thanks a lot..!!:)

bilalmerei July 18, 2010 10:36

2 inlets...
 
Hello everyone.
have you find the way to introduce 2 different velosity inlets?
still waiting for a solution i tried a lot of ways but it seems that i need help

PSYMN October 8, 2010 12:10

My 2 cents...
 
Sorry, there was a lot to follow here and I am not sure on the final status, but someone asked me to comment, so here i am...

1) At the geometry level, you can combine bodies into a multi body part (using the model tree at the top left of DM). This will cause the meshes to be conformal. Not combining bodies into a part will result in them meshing separately... You could then create named selections on each body face where it contacts its neighbor so that you can net up non-conformal interfaces in Fluent... I think there is even an automatic way to do this (similar to automatic contact detection) but I forget the exact steps...

2) At some point (in DM or ANSYS Meshing), you would need to create named selections. Personally, I like to do it in ANSYS Meshing because there are more options and you can't forget to turn on the setting that passes named selections. You would create these for the faces of the bodies (such as Inlet, Outlet, etc.) but you should also create them for the bodies themselves... If all your bodies are supposed to be same zone, just select them all with the body selection tool, right click and Create a Named Selection named Fluid. If some of your bodies are in a porous, solid or other region, you should select those separately and name them. This should take care of the zones, interfaces, etc.

3) as for the questions about how to specify which fluids are coming thru each inlet, how the mixing happens, etc... I am sure there are some Fluent tutorials about that or you could ask the question on the Fluent Solver Forum.

amirmohebbi October 9, 2011 04:49

problem to define another flow in mass flow inlet B.C
 
dear all
hi
I am new in fluent
how i can define all of my mesh zone stagnation air
and mass flow inlet another flow like that fuel
then i have to the mixing rate of them
please help me?
thanks for your attention
amir mohebbi

prishor November 20, 2012 05:03

hi all,
i am doing a multiphase flow simulation in fluidized bed using fluent 6.3. i have to enter air and steam as mixture in material properties. how should i proceed to enter the mixture property as it is currently disabled in material panel. i am doing the simulation without species transport.

please help me.

thanks and regards,

prishor p k

Mahboobe365 June 14, 2013 23:29

Hi all,I have the same problem one of the zones is vapor and one of them is porous with liquid. my problem is that the common line btweeb two zones is velocity inlet for example the water escapes from liquid zone come to vapor zones. But when i use multy parts in ansys , The lines will be defined az wall and i cant define velocity for them . Can you help me? pleasee

mustafa-uslu December 2, 2013 09:43

Quote:

Originally Posted by PSYMN (Post 278469)
Sorry, there was a lot to follow here and I am not sure on the final status, but someone asked me to comment, so here i am...

1) At the geometry level, you can combine bodies into a multi body part (using the model tree at the top left of DM). This will cause the meshes to be conformal. Not combining bodies into a part will result in them meshing separately... You could then create named selections on each body face where it contacts its neighbor so that you can net up non-conformal interfaces in Fluent... I think there is even an automatic way to do this (similar to automatic contact detection) but I forget the exact steps...

2) At some point (in DM or ANSYS Meshing), you would need to create named selections. Personally, I like to do it in ANSYS Meshing because there are more options and you can't forget to turn on the setting that passes named selections. You would create these for the faces of the bodies (such as Inlet, Outlet, etc.) but you should also create them for the bodies themselves... If all your bodies are supposed to be same zone, just select them all with the body selection tool, right click and Create a Named Selection named Fluid. If some of your bodies are in a porous, solid or other region, you should select those separately and name them. This should take care of the zones, interfaces, etc.

3) as for the questions about how to specify which fluids are coming thru each inlet, how the mixing happens, etc... I am sure there are some Fluent tutorials about that or you could ask the question on the Fluent Solver Forum.


Awsome answer. I had the similar problem but solve it after reading your comment. Thanks very much

hamiasmai February 21, 2014 03:21

Thanks and Help and Thanks
 
Quote:

Originally Posted by PSYMN (Post 278469)
Sorry, there was a lot to follow here and I am not sure on the final status, but someone asked me to comment, so here i am...

1) At the geometry level, you can combine bodies into a multi body part (using the model tree at the top left of DM). This will cause the meshes to be conformal. Not combining bodies into a part will result in them meshing separately... You could then create named selections on each body face where it contacts its neighbor so that you can net up non-conformal interfaces in Fluent... I think there is even an automatic way to do this (similar to automatic contact detection) but I forget the exact steps...

2) At some point (in DM or ANSYS Meshing), you would need to create named selections. Personally, I like to do it in ANSYS Meshing because there are more options and you can't forget to turn on the setting that passes named selections. You would create these for the faces of the bodies (such as Inlet, Outlet, etc.) but you should also create them for the bodies themselves... If all your bodies are supposed to be same zone, just select them all with the body selection tool, right click and Create a Named Selection named Fluid. If some of your bodies are in a porous, solid or other region, you should select those separately and name them. This should take care of the zones, interfaces, etc.

3) as for the questions about how to specify which fluids are coming thru each inlet, how the mixing happens, etc... I am sure there are some Fluent tutorials about that or you could ask the question on the Fluent Solver Forum.

I am new and this really helpful! Kudos.
May I add one question: How to make dissolution phenomena between 2 phases? (preferebly tiny solid particles + liquid)

Thank you in advance. :)

landerfwc October 15, 2014 11:50

Mesh connection
 
Hi, I had similiar problem and I have successfully solved it by supressing automatically created contact regions in Ansys meshing. Then, to connect the meshes I created a Mesh connection on appropriate edges.

6863523 October 20, 2014 12:17

Quote:

Originally Posted by landerfwc (Post 514499)
Hi, I had similiar problem and I have successfully solved it by supressing automatically created contact regions in Ansys meshing. Then, to connect the meshes I created a Mesh connection on appropriate edges.

Hi, I am facing a similar problem.
I want to do the simulation of evaporation. There are two regions, one is water vapor, the other is wick saturated with liquid water. the evaporation is supposed to occur at the contact line between wick and vapor.
Need i specify the boundary type? Which kind? Interface? wall? porous-jump?
Thank you. Any suggestions would be appreciated. My email is: 815719752@qq.com


All times are GMT -4. The time now is 00:00.