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BC for a water-air system

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Old   February 20, 2017, 05:30
Default BC for a water-air system
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paolo
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Hi everybody!

the aim of my simulation is to evaluate the interaction in between a flux of air through a flux of water, like in the picture-1 attached.

The solver I'm using is interFoam and the tutorial I used to start is damBreak.
First I tried to implement the inlet flow of water , with turbulent condition, without air flux, and I expanded the volume of study

The boundary conditions I applied are as in the attached files (BC.zip). I choose them based on those of the damBreak tutorial and from a tutorial at this page:
http://www.holzmann-cfd.de/index.php...pump-cyclic-bc

What I get is an error about the number of iterations, as in the attached file (log.interFoam.zip). The log file is shorter than the real one beacause of file dimension.

So, which should be in general the correct (or standard) BC for a simulation like this (and with the air-flux applied)?

Thanks in advance for any kind reply.

Regards
Paolo
Attached Images
File Type: jpg Picture-1.JPG (32.4 KB, 24 views)
Attached Files
File Type: zip BC.zip (3.3 KB, 2 views)
File Type: zip log.interFoam.zip (47.8 KB, 2 views)

Last edited by iopenfoam; February 20, 2017 at 06:01. Reason: Clarification
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Old   February 20, 2017, 07:39
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Hi,
It looks like you used a fixed time step, which causes the courant number to increase too much.

Set adjustTimeStep to "yes" and max courant number to 0.5 in your controldict and it should be better.
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Old   February 22, 2017, 04:21
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paolo
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Hi Sati,

thanks for your hint, it works fine now!
I guess the problem was about a high velocity of the fluid while falling, so with high velocity , but same time step and cell size, the Courant number increased too much and affected convengence.

Thanks a lot!

Regards
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