viscosity ratio in MC-SC

Hi, I’m trying to simulate a T-junction according to [W Wang, Z Liu, Y Jin, Y Cheng, LBM simulation of droplet formation in micro-channels‏, Chemical engineering journal, 2011‏] but in this article they have used the ratio 2 for dynamic viscosity, because in MC-SC model we should use the unit density ratio, I used the ratio 2 for kinematic viscosity to set the equal condition but it lead to produce negative densities, in my simulation. I used the same formulas but why this happen?

The other question is for calculating the surface tension I use a static droplet but when I’m simulating the micro-channels, by changing the outlet pressure the densities change, doesn’t this lead to change in surface tension and Ca number ?


Hi King
I do not know your first question, but as a part of your second question, I need to know how you calculate surface tension? Do you use the Laplace Test? If not try it.
In addition, Do you have contact angle in your case? If a droplet is in contact with the wall you need to determine the contact angle as well.