OpenLB – Open Source Lattice Boltzmann Code Forums on OpenLB General Topics Undesired condensation in multicomponent flows

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• #1964
lollipopcorn
Participant

Hi there,

When simulating multicomponent flows using SC method, I would like to change the interfacial tension between two fluids by changing G value. However, in the case of two fluids of density 1 and 0.8, unexpected condensation occurs when the G value is increased from 3 to 4. How to solve this problem?

Thanks a lot,
John

#2790
mgaedtke
Keymaster

Hey John,

what do you mean by condensation in combination with multiple components? What is your setup up and what is the effect you see there? Please provide some more information, so that I can reproduce your effect.

Best, Max

#2795
lollipopcorn
Participant

Dear Max,

Thanks for your reply. When I say condensation I was actually meaning the precipitation of one fluid in the other fluid. The setup is that fluid 1 is being injected from the left end, displacing fluid 2. (rectangle geometry, constant pressure at right end, bounceback at top and bottom, BouncbackRho1=0.7, BouncebackRho2=0.3). When I increase G from 3 to 4, after the start of the simulation, though most of fluid 1 is still in the left region, I see some little bubbles of fluid 1 precipitation in fluid 2 at up and bottom walls in the middle and right region. it feels like part of fluid one dissolves in fluid 2 and then precipitates at the top and bottom boundary walls.

Why does this happen? especially, if its due to the partial miscibility of two fluids, then, why does it happen when G is 4 but doesn’t when G is 3. since G is a measurement of repulsive forces between fluids, shouldn’t the fluids be “more immiscible” when G is 4?

Thanks,
John

#2799
mathias
Keymaster

Dear John,

What about the initial conditions? How close is the one fluid to 0. Did you try to plax with it like 0.01 or 0.001? Then G=4, the force seperating the fluids in stronger. So, the results seems all right.

Best
Mathias

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