[Saideep]

Hi FOAMERS;

Before you go onto the weekend i have a question for you!!

I am simulating flow through micro channels {2P flow -> using interFOAM solver} and have a serious problem with boundary conditions.

I start with a very simple case having an inlet and outlet face. I keep injecting one phase and it flows through the outlet face. Seems to be quite simple to analyze but what bc do you use for U at the outlet?

I fixed the pressure at 0 at outlet and tried several U bcs {indirectly a zeroGradient bc with additional features} like zeroGradient, inletOutlet {inletValue = 0}, pressureInletOutletVelocity.

But what happens is that there is an inflow of one phase from the outlet and the inflow phase displaces it out. This is quite nonphysical i guess.

I read in some experimental papers they try to neglect the capillary end effects by taking a central region for analysis. Is this something related to that?

I am also not flexible with the field alpha as i have one flow inflow through inlet and mixed flow (zeroGradient) at the outlet face.

I tried the same with many shapes of micro channels but all have this sort of inflow from the outlets. If this is physical what is the reason if not what are the suitable bcs?

Thanks and a nice weekend;
Saideep

[mchehab2]

Hi saideep,

try to use
U:
outlet
{type inletOutlet;
inletValue uniform (0 0 0);
value ( 0 0 0);
}
how did you make the phase flows, would you show me the code?

[mchehab2]

i am doing multiphase example, when i use fixedvalue for velocities, the vectors dont move when simulating ( there is no flow), how can i make the vectors flow when simulating the model?

[Saideep]

hi,

i tried inletOutlet but i guess in order to maintain continuity it still breaks up the bc and injects the phase at the boundary face.
Also i read elsewhere it isnt a strict bc. There should be something more effecient than that i guess.

I guess your setFields data are incorrect. Can you notice your phases at 0 time step? Then applying your alpha, U, p_rgh are straight forward.

Saideep

[mchehab2]

where do i get the setfield data from?

[Saideep]

i guess you were too fast to experiment.

You find that in system folder. The aim of setFields is to specify the initial location of specific phase in your system.

For getting started try damBreak example from user manual. It gives you a basic idea of how interFoam works.

Saideep