The contact line problem in the case of hollow droplet impact

[Han Luyang]

Dear all,

 

I am a beginner in Basilisk and currently conducting numerical simulations of drop impact on superhydrophobic wall. The contact angle of the wall is set through the height function. During previous simulations of normal droplets, using a free-slip boundary condition to simulate a 154-degree contact angle impact achieved good results.

 However, when I attempted to add a bubble in the droplet, the identification of the contact line was extremely poor. As shown in Figures ContactLinePinned1&2.png, the contact angle seemed to always be identified as 90 degrees and there was severe "contact line pinning" which also led to subsequent evolutions being non-physical. I tried changing the boundary condition to no-slip and adding Laplace pressure to the bubbles (SingleForce_Hollow.c), but the result did not improve.

 

Furthermore, I also experimented with different combinations of bubble physical properties, Weber numbers, and Reynolds numbers from several other papers, but found that none of these solutions addressed the issue.

 

I sincerely hope to receive help from all of you. I have been troubled by this problem for a long time!

 

 

Best regards

 Han