[praveensrikanth91]

Hello,

I am trying to generate a static liquid plug in a capillary using interFoam. The two fluids are air and water. I set up the initial water region as in the figure

And on running interFoam the final solution i get is something like

instead of the expected liquid plug. This is also oscillating as the droplet in the middle increases and decreases in size with time. I am wondering if it is a problem with any of the boundary specifications that i have done. I have attached the case folder with the post and I am hoping that someone would be able to help. I am unable to attach the mesh file as it is a 3d mesh with 600k cells and is very huge. It is a simple cylindrical capillary

Many thanks

[snak]

Hi Praveen,

Increasing liquid volume or decreasing a cylinder diameter will make a plug.
The contact angle of 45 deg at the wall pulls liquid to the wall.
Decreasing surface tension, sigma, may make a plug because a low sigma tends to keep an interface flat.

good luck,

[praveensrikanth91]

Hey Shinji,

Thank you very much for your reply and going through the files.

I thought so too that the contact angle should make it a plug. The volume that I had given is the minimum volume required to have a plug solution for a contact angle of 45 and the diameter of the capillary. Do you think it should be run for a longer time? I am going for something like this


That is the model I generated with the plug and if this doesn't automatically collapse to that because of the surface tension and contact angle then I have to mesh this in ICEM and denote a separate region which I am still trying to figure out as to how to do it.

[praveensrikanth91]

I still haven't managed to get a stable liquid plug solution for the case I want. It does work for higher fluid volumes. The case that I am looking for is a minimum volume condition for a plug. The minimum volume is calculated using an analytical formula and the corresponding radius of curvature of the plug as well. I set up a case with the plug as the initial condition for a contact angle of 45 degrees.



but on running interFoam with no changes at all while I expected the plug to remain as such it collapsed into an annulus which is not supposed to happen.



Please let me know if you have any idea as to what could possibly be the problem and if you need any additional information to help

Many thanks