well, i tried to carry out such a mesh, after duplicating the boundaries and creating a new region, i get the message: "Error: could not match up perimeters of boundaries Boundary 14 and Copy of boundary 14". What's wrong ? I took the correct procedure to duplicate the boundary creating interfaces... help me please !!! Thank you in advance, Mike

If the two surfaces are not topologically identical in the interface you either have to remove the interface and re-apply after volume meshing or put them in different mesh continua

the problem is that i cope with two fluids, entering the model by two different inlets. i tried to make two separate continua under the "continua" column, but that doesn't work. so i tried with a multi-phase mixture (what in effect is), but it shows a problem with memory (perhaps initial conditions i gave are still quite rough). actually i don't know waht's the best path to choose, whether the two mesh-two continua regions or the multiphase simulation.. could you please tell me what's your experience ? thanx in advance, mike

Are the two fluids miscible? If so you should only need 1 continua and the multi species model if not then you can use VOF. You shouldn't need two mesh or physics continua.

Let's say, the fluids are air and water... what's this multi species model you say ? i can't find it in the selection... thus, using two physics continua i get an error on generating volume mesh: after having create the interface by the common boundary, and have splitted it in a new region, it recognizes this surface as a nonmanifold one... it says it contains non manifold edges... so unconfortable...

It probably helps to study some of the tutorials, since your questios are answerd there.

The multi species model is in the material selection bit of the physics continua setup wizard thingy, but it should be noticed that this is for miscible mixtures only. If you are using air and water, if the water is in liquid state, then you will need VOF as a free surface is present.