Errors using contact-embed.h in parallel channels inclined with the grid

[Willemijn Van Rooijen]

Dear Basilisk Users,

My name is Willemijn van Rooijen, and I work with Stéphane Zaleski and Hadi Hajibeygi on contact line movement in channels with embedded surfaces. Initially, I focused on two-phase flow in straight channels using contact-embed.h.

I have two separate issues with contact-embed that I am going to send in separate emails.

I have encountered instabilities and observed deviations from the imposed contact angles. Attached is a sample code illustrating the problem. The channel is inclined with the grid.  A contact angle of 90 degrees is imposed, the embedded surface does not intersect any grid corners, and the capillary number remains at 1e-3. As you can see in the attached image, the interface is very unstable, particularly at the bottom, and fails to maintain the imposed angle. The extrapolated interface facets in the solid are chaotic.

I'm reaching out to see if anyone within the community has encountered similar difficulties or might have insights into resolving this issue, and to coordinate with anyone already trying to solve this problem.

Your help is greatly appreciated.

Kind regards,

Willemijn van Rooijen