[1988]

hi
I have simulated a micro channel which has been made by main and lateral channels, in the main channel, air as continues phase and in lateral channel, water as dispersed phase are flowing. I made structural and uniform mesh through the whole geometry and I have got these results which have been shown in the picture 1.
As it is obvious from the pictures in small capillary numbers, the droplet length become bigger and bigger in the channel after the breakage. Contact angels were defined 150 at the main channel’s walls and 0 at the lateral channel’s walls and the same results have been gotten. But I have 2 problems.
1.Why in small amounts of capillary number the droplet length become bigger and bigger through the channel? Do you have any suggestion? By mesh refinement nothing has changed. And I use to dynamic contact angle but it isn't different.
2-In picture 2 (I took it from an article) during droplet breakage, the air from main channel goes inside the lateral channel and this curved part has been formed( as you can see in the picture) but in my simulation in picture 3 this effect (shown by yellow circle) this curved shape was not formed. what is wrong in my simulation?
Do you have any idea or suggestion?
I have used contact angel 0 in lateral walls and 150 in main channel walls. What is the right way of contact angel definition?
thanks
u and alpha water files were attached

[wyldckat]

Greetings Ali Reza,

I've had this thread on my to-do list for sometime now and I've finally managed to look into this.
If you had provided a test case, I could have tested this myself and try to isolate the problem.
Since you did not, my guess is that what you're seeing is that the fluid is sticking to the walls of the tube, which is why the surface on the wall becomes longer along the tube.

Have a look at the following FAQ on the topic of mesh diagnosis: http://openfoamwiki.net/index.php/FA...is_in_ParaView - the idea is that you can use the "Extract Cells by Region" filter in ParaView, to look into the cells within the tube, to confirm what values it has inside it, to confirm if my theory is correct or not.

Best regards,
Bruno