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2D Droplet break up in plannar flow focusing geometry
Posted Apr 4, 2017, 10:52 a.m. EDT Fluid & Heat, Computational Fluid Dynamics (CFD), Microfluidics, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 5.2a 3 Replies
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I am trying to simulate the formation of water-in-oil droplets in a plannar flow focusing geometry.
The physics I am using is the laminar flow-phase field.
The boundary conditions for the inlets are the flow rates that I used experimentally.
The simulation "runs" "properly" only when the option Neglect surface tension in momentum equation is activated.
Once I activate this option, the computation process takes ages ( stuck at 4%) and eventually crashes.
I would appreciate if you could provide any advice related with this issue. I am confident it is just a small but critical mistake in the settings of the model.
Attachments:
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Sorry I couldn't run your file on my machine since it was busy. I saw your file and everything looks fine.
However, your meshing seems inappropriate. The mesh size is too large in some regions and too small in the corners. Fix it at first.
You know that the maximum element size determines the thickness of the interface. Try either:
1) Reducing the maximum mesh size.
or
2) Set the interface thickness manually (give it a value instead of hmax/2)
Amin,
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Thank you for your reply. Unfortunately the simulation gives the following error:
"The following feature has encountered a problem:
Failed to find consistent initial values.
Undefined value found.
NaN or Inf found when solving liner system using SOR.
Last time step is not converged.
- Feature: Time-Dependent Solver 1 (sol1/t1)"
The mesh is indeed quite messy, but I think the problem comes from another source.
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I made a few minor changes to the file you attached and it is working now.
My changes:
1) Remeshed the geometry.
2) Changed all the inlet entrances from 1m (default value) to 0.1 mm. Your domain size is in the order of mm and the inlet entrance of 1 m is physically inappropriate .
See the attached files.
Good luck.
Amin,