Eulerian VOF method-outlet boundary?????
 

Hi

I am doing a 2D simulation for the movement of a water droplet having Diameter 25 micrometer through a channel of cross scetion 50 micro X 500 micro..
Using Eulerian VOF coupled method to explicitly define the velocity of droplet and oil phase

I patch the droplet phase and assign a volume fraction of 1 to that water droplet patched region

I am using transient case with double precision

Oil as primary phase and secondary phase as droplet
scheme: phase coupled SIMPLE gradient : Least sqaure method Momentum : first order upwind volume fraction: geo construct

Inlet BC: velocity for oil and droplet volume fraction zero and droplet velocity also at inlet

when i am using Outlet boundary condition
I have to define the back flow volume fraction.
initially If i give the back flow fraction as 0 the simulation running fine and give the correct tracking of interface also

For me i want to eject the droplet from the exit.But by this condition after the simulation the droplet is stuck at exit.solution gets stopped by the high courant number

Similarly i tried with outflow BC.at that time also simulation perfect upto reaching the outlet then again the simulation stopped and the droplet is not going out.

When i tried outlet boundary condition with back flow volume fraction of droplet as 1 it is showing error ->Solution diverging ..velocity diverging .Global courant number more than 250..

Please help me to eject the droplet from the channel during simulation.For that what BC should i give at outlet...

My email ID sajeeshperil@gmail.com


Thanking You

sajeesh

Hello,

I am also working on similar Project on wetting Dynamics of an indium droplet. Can you send me your files, so that I can recommend something mehmet.yigit.balta@gmail.com

sir what files you want....

case and data file

yes please send me case and last data file so that i can look through

sir
did you get my mail..have seen the files....pls reply me..if you got it


Sajeesh

sir
did you get my mail..have seen the files....pls reply me..if you got it


Sajeesh

droplet
 

Hi saajesh:

I think you should try like this:

1 Finer mesh

VOF method instead of Euler

Implicit instead of explicit

Servers:

Pressure based Coupled

Least square cell based

Quick

Quick

Small time steps (like 1e-6)

My droplet and tank project with wall adhesion worked like this

Sorry for the late answer, Good luck!

Thanks sir for reply

How i can give velocity for the droplet if i select the VOF model

I want to give different velocity for the droplet.

To study the internal external velocity vectors at differnt flow rates of discrete phase

Sajeesh