inlet boundary condition based on specified water level
Hi,
I am dealing with a two phase flow problem where I need to specify a constant water level for the inlet. I do not want to do it by specifying a velocity or flux. I tried to do it by specifying a hydrostatic pressure (rho*g*h) for p_rgh and zeroGradient for U but it blows up! Is there any way to specify the height of the water at the inlet? Thanks Hale |
well i guess you can do it via non-uniform alpha1 (i assumed you use interFoam as solver ;) )
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Thanks for the reply. Yes, I use interFoam. For the inlet where I need a constant water level I have defined alpha1=1 and zeroGradient for everwhere else. What did you mean with non-uniform alpha1? |
well you can put a non-uniform alpha
something similar this : Quote:
you can used: 1- code stream 2: groovyBC to create such nonuniform BC |
This is too complicated for me :) but would you please explain what will this non-uniform alpha1 do? I need a uniform water level at the inlet so why should I changed alpha1 to non-uniform?
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in your post #1, you said you want a constant water level!, so i assumed! a portion of your inlet fill with water! if the whole inlet is water! then specify the velocity or flux whats wrong then? ;)
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The problem is that I'm simulating a real life problem where the flux is not known but the water level can be adjusted. Therefore I want to specify the water level in terms of hydrostatic pressure or something else that can allow the model to find the flux/velocity by itself.
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Different water levels; BCs OpenFOAM
I have a similar problem. I have two water tanks connected by a pipe. The tanks have two different water levels. I want to keep this difference constant but I do not know the flow rate at the inlet and outlet. Therefore I should find the BCs that allows me to keep the water levels constant in the tanks. Any help?
Thank you |
I have a very similar problem for open channel flows
What I need is an upstream boundary that physically behaves like there would be an unlimited reservoir of water with a fixed water level and no prescribed flow rate / velocity at the boundary. Velocity at the upstream boundary should develop as a consequence of the velocities in the model. I have tried to fix upstream water level with groovyBC: Upstream BC ------------------ alpha.water: pos().z <= waterlevel ? 1:0 U: zeroGradient p_rgh: fixedFluxPressure Downstream BC (simulating free outflow) ------------------- alpha.water: inletOutlet, inletValue uniform 0; U: pressureInletOutletVelocity p_rgh: totalPressure p0 uniform 0; Atmosphere ---------------------- alpha.water: inletOutlet, inletValue uniform 0; U: pressureInletOutletVelocity p_rgh: totalPressure p0 uniform 0; These BC seem to work nicely with a very simple rectangular open channel flow. With more complicated meshes the simulation seemed to blow up, developing unphysical pressure/velocity from one point near the fixed inlet water level. I suspect the combination of zeroGradient for U and fixedFluxPressure for p_rgh at inlet is not stable. Any ideas which combinations for p_rgh and U could work when fixing the inlet alpha.water level with groovyBC? Hints are highly welcome! Tinu |
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Thanks for sharing the BC.I am simulating flow past plate with free surface.I will try your BC. Sent from my iPhone using CFD Online Forum mobile app |
Defininig flow depth as a boundary condition
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I am trying to define flow depth as boundary condition for an open channel model. This suggestion of yours seem reasonable. However, I could not find out how to apply this in the alpha.water file. Can you or anyone help on this issue? Thanks. |
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Failing that, as someone at the start of the thread mentioned, you can do the same with some pretty codeStream coding. Check out the following: http://www.wolfdynamics.com/wiki/pro...streamINIT.pdf |
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