dear everyone

how to model three seprate region (fluid-solid-fluid), what would be the appropriate boundary conditions on interface region to process the convection-difusion-convection in three different materials(my problem is :fluent treaet every region seperatly with no interaction with them)

You must specify in gambit the type of regions i.e you must coice fluid to the first zone , solid to the second and fluid to the third.in fluent you dont need to do any thing since the fluent will creat a shadow wall with the walls seperating two different adjecent regions. you need only to check that the thermal boundary condition on the interface wall to be coupled .the fluent automaticlly solve the conjugate heat transfer i.e solve the energy eqaution in all trhee zones with coupling boudry conditions.

I hope this will helpful

dear rosol I have already defined these zone in gambit(fliud and solid zones) but it seems that fluent treat each zone separately(there is no temperature gradients across the three zones ie disturbance does not travel from fluid to solid through interface boundary)

Please check that is there are a shadow walls are created in the interface walls if so and the thermal B.C is coupled so the three zones is coupled together.f not you have aproblem in ploting the zones in gambit I think its not in dirct contact

dear rosol thanks alot for ur replay. the shadow walls are generated in fluent so i think there is no problem with interface wall, but let me know how to couple the thermal B.C. at interface wall to allow for thermal graidient at interface boundaries

only check the therma B.C at the interface wall it must be coupled not heat flux nor temp

[arunachalam.siva]

Mr.reem
In gambit U use split option u will create the wall shadow automatically

[wave11]

Dear all,
i would like to know how to get the coupled boundary condition. it is not available under thermal.
also in gambit, i've already set the continuiity type to SOLID and FLUID respectively. but i couldnt get the shadow zone.
please enlighten me.
thanks in advance

[FluentNewbie]

Hi reem,

First, ensure that Fluent creates "shadow walls" for each "interface", then you can go to "define", "grid interfaces" and create grid interfaces. Don't forget to check the "coupled" box.
When done, go to "boundary conditions" and choose "set" for your wall. under "Thermal" you can check the "coupled" option and define you material.

Good luck!

[Behnam Ghadimi]

hi H&A,
i do what you said with some scrupulosity. but i couldn't be able to have coupled boundary condition.
can you help me?
thanks a lot
Behnam

[madhuvc]

Behnam,

you wont be able to use coupled boundary condition if there is not shadow walls created. this will be created by default by FLUENT, when you have shared boundaries between two different regions.

You have to make sure that you have shadow walls, in which if you go to the thermal tab you can see options for coupled BC.

[Behnam Ghadimi]

hi madhuvc, thanks for your replay. i did it, fluent created shadow wall.
But now i have another problem, are you know, how can we rotate a brake disc in fluent by using hexa mesh, i write UDF for dynamic mesh. fluent can rotate model with tri mesh but can't be able to rotate model with hexa meshes.
thanks

[Cyrus69]

Hi everyone
I'm simulating a heat transfer problem that consists fluid & solid zones.I meshed it in gambit & specified zone type(fluid or solid).I put the interface BC between solid & fluid & fluid & fluid as "wall".when I import it to fluent, all these walls become couple.i want to simulte convection between 2 fluid,but i can't enable convective thermal boundary condition.that's my first problem.
My second question is that, is there any way to simulate heat transfer and not choose wall BC? i've tried pressure outlet for one of my fluids but I got divergence error.