define vof in flip bucket spillway???
 

:confused:hi dear all I'm working on a project with one of my friends i do making geometry and the mesh, but I did have problems in the ansys cfx settings , i attach picture of my model in pdf file.I have modeling a flip bucket spillway for compared numerical and experimentaldata, According to the experimental data My goal here is to for Q=600 verified my model, but according Q=VA, basing experimental data in inlet section with depth and velocity with value( D=1.01, b=33.88, v=27.68) my Q is equal to Q=947, because inlet section input after aeration , I think the inconsistency Q due to the high amount of mixing water and air in model.
My problem is the definition of the volume fractions of water and air , note that I read free surface flow over a bump but in this model inlet and outlet At a high level were not,How do I define VOLUME FRACTION UP AND DOWN ( WATER AND AIR)?
whether to achieve the flow rate(Q=600) at the inlet based on experimental data?
I'm so confused and do not mind learning theory, Friends if you have any advice please tell me
Thanking you in anticipation.
regards

Are you sure your inlet condition is appropriate? You have not included the losses associated with the entrance to the spillway.

vof?
 

:confused:hi glenn horrocks , thank you for taking time for me
I considered inlet section in L point , that drawn in attached image, i have completed data for L point( i.e velocity, pressure, depth) ,that i selected velocity and depth in inlet section, but discharge(Q) according experimental data for Q=600 with experimental data for L point Is inconsistent, note that my experimental data is valid, I asked my question of teacher, he says because of the mixing of water and air in the model. with information data in inlet L point my discharge obtain Q= 947, Now the situation , how define volume fraction in model?

Thank you for your attention

excuse me, i forgot attach my image in previous post

I am no expert in spillway design but most the spillways I have seen are very aerated when they discharge. This means a homogenous free surface model is not going to work. You are probably going to need an inhomogenous model, but probably still with a free surface model. Then you can model the free surface, water and aeration of the water.

This approach makes it easy to define a volume fraction for the incoming flow. You just put the aerated bit in the aeration volume fraction.

define vof in flip bucket?
 

:confused:You just put the aerated bit in the aeration volume fraction????
If it is possible for you, You mean to express more clearly. If you can explain a little more about the definition of the volume fractions, how define aeration volume fraction??
Unfortunately, none of the guys did not help me
thanks a lot for the time that I put.

First of all - Do you expect the flow in the spillway to be highly aerated? I need to know if I am on the right track.

define vof in flip bucket?
 

hi dear glenn horrocks, thank you for spending time for me.
as respects, i considered my geometry after aeration ramp, Unconscious a lot
of air entered in my flow, so my fluid volume increases that i think inconsistency Q is Resulting from aeration. So I think the impact of aeration must be considered.
thanks a lot

In that case a homogeneous free surface model will not work. You will need an inhomogeneous free surface model like I describe in post #5.

So make sure you are famniliar with homogeneous free surface models (for instane the free surface flow over a bump tutorial) and inhomogeneous multiphase models (like the multiphase flow in a mixing vessel tutorial). I do not know of any inhomogeneous free surface model tutorials so you are going to have to work out how to combine them yourself.