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-   -   Cyclic inlet/outlet + specified volumetric flow rate possible? (https://www.cfd-online.com/Forums/openfoam/185126-cyclic-inlet-outlet-specified-volumetric-flow-rate-possible.html)

eivind March 19, 2017 15:52

Cyclic inlet/outlet + specified volumetric flow rate possible?
 
Hi!

I am modelling water flowing over a gravel bed for my masters thesis.
In order to reduce the length of my domain I would like to use a cyclic boundary condition connecting the outlet to the inlet using a cyclic BC, (e.g. cyclicAMI).

Using cyclic BCs for inlet and outlet, is there a way to at the same time specify the volumetric flow rate?

This is important because I am intend to compare the simulated results to experimental results from lab measurements with a given flow rate.

Any suggestions would be very much appreciated!

Cheers,
Eivind

fumiya March 20, 2017 02:13

You might want to check if you can use meanVelocityForce or patchMeanVelocityForce fvOptions.
The channel395 tutorial is a good example case:
https://github.com/OpenFOAM/OpenFOAM...LES/channel395
http://caefn.com/openfoam/fvoptions-meanvelocityforce

Best regards,
Fumiya

eivind March 20, 2017 07:41

cyclicAMI - must the geometry of patches be exactly the same
 
1 Attachment(s)
Thank you, fumiya, that was exactly what I was looking for!

Now, I have encountered another problem regarding the cyclicAMI boundary condition.
As the gravel bed geometry is irregular, the inlet and outlet patches do not completely match eachother near the bed (i. e. the boundary of the patches mismatch somewhat along the bottom).

My question is:
Is the cyclicAMI BC going to work when there is some mismatch between the geometry of the slave and master (inlet and outlet) patches? Or do they have to be exactly the same?

If not, any other suggestions to implement cyclic inlet/outlet for my case?

I haven't tried a lot yet (and am quite new to OF), so if anyone could tell me if it should work in principle or if it is impossible I would be very thankful!


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