Learning Forum

[Prashant Jha]

Hello all, I am tring to do simulation of multiphase flow and have defined the phases. My phases are one on top of other, but when i preview my phase distribution before starting the simulation then between two phases no sharp interface is there. I have attached the image for reference. Any clue on why this is happening and how to rectify it.

[SRP]

Hi,

Try to patch phase by creating appropriate region or you can create separate zone to patch regions.

Thank you.

[Prashant Jha]

i think i have done so. I first marked the three regions in the cell registers options and then patched the phases with their respective regions. 

[SRP]

Hi, 

Can you try to plot contours and share here for single phase individually just to verify how it is displayed?

Thank you.

[Prashant Jha]

also, when i run the simulation, then after about 25 time steps, that gree color distortion appears and it becomes perfectly flat, but actually the sharp interface should be there from the beginning.

[SRP]

Hi,

Can you please try to replot the contours keeping nodes values off? 

And can you share the patching setting that you have incorporated?

Thank you.

[Prashant Jha]

yes, now i can see the problem, when i turned off the node values.

For patching, in the patch window, for phase 2, i am giving value 1 to region of phase 2 and value 0 to regions of phases 1 and 3. Similarly, for phase 3, i am giving value 1 to region of phase 3 and value 0 to regions of phases 1 and 2.

[SRP]

Hi,

Great. Be careful during patching as only the secondary phase volume fraction is solved in case of VOF. Primary phase volume fraction is deduced from secondary phase volume fraction.

Thank you.

[Prashant Jha]

ok so the values which i am giving for patching are correct??

 

[SRP]

Hi,

Looks good. Try running to get your desired results and check ansys user's guide: 25.3. Setting Up the VOF Model (ansys.com)

And theory manual for more details: 14.3. Volume of Fluid (VOF) Model Theory (ansys.com)

Thank you.