Hi! I wanted to make two volumes and connect one another, so that gas flow in from a face of one volume and flow out to a face of other volume. But, the boundary conditions (or operation condition) must be set different for each volume.

At first, I have tried to make two volumes and unite them. (There is now one volume) Gas did flow, but I could not set the b.c. for each volume.

Then I have tried to unite them with retaining the volumes. (Now, there are three volumes) I could set the b.c., but gas didn't flow. (The result was same, when I didn't unite volumes)

What's wrong? What should I do?

Hi,

Whats the difference in the BC. You can use Interior BC as the common face, but I m not sure you can change the BC or not.

Regards, Titiksh

DId you create your geometry using GAMBIT?.

If yes this what happens when you try to unite two adjacent volumes; you'll get the message that volumes are not connected.

One option is to break a volume with the other, but you may end up gettting funny results if you have a 3D mesh. You may loose it.

Another option that may work pretty well; you mesh the two volumes and then you export the whole mesh as a *.msh file or the like depending on the solver that you'll choose. You then import the mesh back into GAMBIT. You'll get again two different meshed volumes but you can merged them with no problem at all.

Create the two separate volumes and put your boundary conditions for both the volumes. Set the boundary condition for the 2 common surfaces to interface in Gambit(you can also do that later in Fluent).

Use tgrid to merge the two volumes into one. Open Fluent and then use the grid interface under define (change the 2 common surfaces to interface, if you have not done it earlier in gambit) to join the two volumes. There is an example tutorial also in Fluent for this kind of problem.

Hope it helps.