VOF multiphase analysis of a micro-Nozzle
 

Hello, I am working on two phase (helium and water) volume of fluid analysis of a micro-nozzle, to study the formation of jet and effects of boundary conditions on the jet.
I need help to verify whether the solution models and controls im using are right or wrong because the results im getting are wrong (according to experimental data).

General:
Pressure based
Axi-symmetric

Models:
Volume of fluid (implicit)
Implicit body forces checked
Interfacial anti diffusion Checked

Boundary conditions:
velocity inlets on body Helium and water inlet
Outlet = Outflow

Solution methods:
Pressure velocity coupling = coupled , coupled with volume fraction

Solution Controls:
flow courant number = 0.25
Vof Courant number = 0.25

Time step size = 10s
Number of time steps = 2000

Hello,

First comment is the time step .. this is too large. To estimate your time step, calculate dt = dx/U where dx is the minimum length scale and U is the maximum velocity in your domain. It is better even to go to less than half this value.

Second, Outflow boundary conditions is not recommended in two phase flow. You need to make it Outlet Pressure

Third, The results are function of the model as well as the mesh ... you might need to increase the mesh quality and/or refine your mesh