SWFS Transient Multi-Fluid Mixing in Closed Volume
 

Hello all! First time poster here. The best I could tell, this is the sub-forum to post about SolidWorks Flow Simulation questions. Apologies if this is in the wrong place.

I'm pretty new to using SWFS, and what I've done with it has been limited to single fluid steady-state simulations. But I've been asked to look at doing a simulation of a liquid fuel that is pushed out by a hydraulic fluid. The fuel is isolated in a closed volume by burst disks. Hydraulic fluid enters on one side to open the inlet burst disk, which then mixes into the fuel and pressurizes the volume. This pressurization opens the outlet burst disc and the fuel and hydraulic fluid mixture flows out the other side.

Some specific things (events) I've been asked to look at are:

1. Inlet hydraulic pressure rise rate prior to rupture of inlet burst disk
2. Hydraulic fluid flow into the closed fuel volume, and the pressure rise rate prior to rupture of the outlet burst disk
3. Fuel and hydraulic fluid mixed flow exiting the volume after the outlet burst disks opens, to evaluate how quickly the fuel fully empties from the volume (or if is fully empties at all).

My general approach to this analysis would be to break it up for each event: 1, 2, 3. I assume that modeling the sudden 'opening' of the burst discs would not be possible in SWFS?

I'd like to get this communities thoughts on approaching this problem and the challenges/limitations of doing this with SWFS. Any advice for tackling this analysis would be greatly appreciated.

Thank you so much for your time, and I look forward to reading your responses. :)

Hi Scott,

Yes, the general approach is correct.
All simulations would have to be in transient.

1.
You can model the fluid flow until a certain value of a goal is reached and then let the calculation stop. That is done by defining a pressure goal for example on the inlet burst disc and set the stopping criteria in the calculation control options of that goal not on "auto" but on ">absolute value" and use the value at which pressure the disc would burst. Also use not "All goals" as convergence criteria but only the one you are interested in to let it burst and stop the solver.

2.
The next step would be to deactivate the lid which was representing the burst disc and use the transferred initial conditions to get the flow distribution for the second simulation so the hydraulic fluid flows into the fuel and mixes. After a while also here the pressure goal should reach the stopping criteria for the outlet burst disc.

3.
Then use again the simulation results of the 2nd simulation for the 3rd and analyze for any desired length to see what the concentration of the mixture does over time.

I hope this helps,
Boris