[COMSOL_Users] Navier Stokes - Open Channel Flow

[hermano]

Dear all,

Has anyone ever used comsol to model open channel flow? I am trying to
simulate a simple example of flow over a broad crested weir (in 2D),
and I am using the two examples available in the library to give me
ideas on how to model this problem. They are: the "sloshing tank" and
"fluid structure interaction". However, the simulation is not working,
although I believe I used the correct boundary conditions.

I have read some of the messages on the board which suggest a
k-epsilon turbulence model (instead of the navier-stokes in the Fluid
Dynamics Module) in the Chemical Engineering Application Module since
the flow conditions are likely to be turbulent. Would anyone perhaps
have an idea where to find additional libraries for such cases or if
someone has worked on this specific example and is willing to give me
some advice? There is very little mentioned regarding open channel
flow in the documentation. Thank you for your attention.

Regards,
Mahmoud Al-Riffai.

[jalal dehghannya]

Dear Mahmoud Al-Riffai,

The Navier-Stokes equations can be used not only for all types of Newtonian incompressible laminar flows, but can also describe turbulent flows. However, modeling of turbulent flow with the Navier-Stokes equations requires that you should use very fine mesh in order to be able to resolve eddies. I have successfully used the Navier-Stokes equations in highly turbulent flows for forced-convection cooling of spheres.
If you think that the turbulent models (such as the k-epsilon model) can describe your simulation in a good way, you may want to look at the "New Features Guide" in COMSOL 3.3a. There are some examples in Chemical Engineering Module 3.3a model library update such as " Turbulent Flow Through a Bending Pipe" and "Turbulent Flow over a Backward Facing Step".
Regards,
Jalal


hermano <***@yahoo.com> wrote: Dear all,

Has anyone ever used comsol to model open channel flow? I am trying to
simulate a simple example of flow over a broad crested weir (in 2D),
and I am using the two examples available in the library to give me
ideas on how to model this problem. They are: the "sloshing tank" and
"fluid structure interaction". However, the simulation is not working,
although I believe I used the correct boundary conditions.

I have read some of the messages on the board which suggest a
k-epsilon turbulence model (instead of the navier-stokes in the Fluid
Dynamics Module) in the Chemical Engineering Application Module since
the flow conditions are likely to be turbulent. Would anyone perhaps
have an idea where to find additional libraries for such cases or if
someone has worked on this specific example and is willing to give me
some advice? There is very little mentioned regarding open channel
flow in the documentation. Thank you for your attention.

Regards,
Mahmoud Al-Riffai.






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