# How to model Fluid Reservoir in SolidWorks?

Engineer have spherical but symmetric pressure vessel.

Inside this pressure vessel there is water.

I have a series of (lets call them) soda straws blowing air through the water.

And then an exhaust a the top of the tank.

I am trying capture what configuration of "soda straws" creates the lowest pressure drop. I am not looking to do multi-phase flow.

My problem/question stems from the fact that for the life of me, I cannot figure out how to model the water level in this vessel as it has an air-gap at the top.

I've tried using a cap and fluid subdomain and have tried putting a solid in that would be the water volume and disable that solid.

Neither approach worked.

### 2 Answers

I did not get the question sketch might help. Are you trying to model the airflow through the liquid? And having problems with the liquid boundary conditions?

If that's the case you have to set up free energy BC if the software allows, or model the boundary layer which eventually holds the liquid together, then dynamically control the BC for each air bubble which appears throughout the time (each integration step).

If by meaning non-multiphase you mean not only discarded phase transitions, but everything, then you are having one substance flow only (which is air) and I do not see a problem. Let me know if anything else I might help.

BTW, Navier-Stocks is the worst way of solving those types of problems and also the most complex, if you are interested, let me know as well.

This is a complex and multiphase CFD question if i get it right. By multiphase, i mean the air blowing through the water. One phase: liquid water, other one: gas air. Any assumption (like defining a solid etc.) will not model liquid water right, even if you succeed getting results, it will be wrong. Water definitely flows when you blow gas in it. You must model the water as water, modeled with NS equations considering turbulance. It is like; Pressure that is exerted on your nozzles tip can not be modeled with height - weight calculations. Fluid movement fluctuations will be very effective. Like bubbles get bigger and begin acting different elevating in water, thus change the water pressure on your nozzles. Unfortunately, solidworks fluid modeling will not be enough for this problem (as i know there is no multiphase flow in that, i may be wrong with newer versions, though you should consult to a CFD experienced person that have used the software before, such as the person who sells it in your region to get true results). You should use Fluent, CFX, OpenFOAM like CFD software to get results. If you need help or maybe consulting, contact me... Hope i've understood the question right. If not, please warn me.