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-   -   VOF-Simulation using InterFoam (Laminar) (http://www.cfd-online.com/Forums/openfoam/79721-vof-simulation-using-interfoam-laminar.html)

ronaldo September 1, 2010 11:15

VOF-Simulation using InterFoam (Laminar)
 
Dear All,

I am simulating a VOF using interFoam (laminar). I have a time step of 1x10^(-6) sec. This means I have to wait quite long for my simulation. could someone tell me how to get the time step higher.

Thank you in advance

flowman September 1, 2010 21:06

You can use adaptive time stepping base on Courant number

sega September 2, 2010 02:52

Quote:

Originally Posted by flowman (Post 273679)
You can use adaptive time stepping base on Courant number


... or even set the timestep manually (which I would not suggest).
All to be read in the User Guide.

kwardle September 3, 2010 16:23

interFoam timestep tips
 
I assume you have already tried using "adjustTimeStep yes;" in controlDict to get a Courant adaptive time step as was suggested.

If you use interFoam in 1.7 it also has a definition of the Cr according the the main flow and a separate one for just this interface region. Take a look at the damBreak tutorial to see controlDict definitions. Set maxCo to 2. and maxAlphaCo to 1. This should help you push the timestep to the max.

If the timestep is still quite small check your solutions for erroneous regions of high velocity that may be driving it down. I have found this sometimes happens near pressure outlets with unwanted air ingress.

Hope this is useful.

akidess September 6, 2010 03:43

Quote:

Originally Posted by kwardle (Post 273960)
If you use interFoam in 1.7 it also has a definition of the Cr according the the main flow and a separate one for just this interface region. Take a look at the damBreak tutorial to see controlDict definitions. Set maxCo to 2. and maxAlphaCo to 1. This should help you push the timestep to the max.

A maxCo of 2 seems way too high to me for a stable PISO solution, and from what I know using a VOF method tightens the Courant limit even further. Have you made different experiences?

ronaldo September 6, 2010 05:04

thk akidess,

i have made different experiences. When i increase the maxCo, the time step becomes smaller. The maxCo in my simulation is 0.3

ronaldo September 6, 2010 05:15

thk kwardle,

i use interFoam in 1.7. IŽll set maxCo to 2. and maxAlphaCo to 1 and geve you a feedback.


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