interForm static capillary interface
 

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 http://www.cfd-online.com/Forums/att...1&d=1392850272

And on running interFoam the final solution i get is something like http://www.cfd-online.com/Forums/att...1&d=1392850272

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

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,

Thank you
 

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
http://www.cfd-online.com/Forums/att...tter.net-.jpeg

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.

Help: Quick Update
 

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.

http://www.cfd-online.com/Forums/att...1&d=1394171061

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.

http://www.cfd-online.com/Forums/att...1&d=1394171061

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