Optimize Multiphase Simulation

Hey there,

First of all: I read the topic “Optimize Simulation” and tried to transfer the suggestions to my mesh, but in my Opinion the main Problem there ist the overall quantity of cells. I don´t think that this counts for my mesh with something like 650K cells.

I finally managed to run my multiphase Simulation and with the help of a colleague we could speed it up by the factor of two.

We did this with a new moderate hex dominant mesh instead of the standard algorithm. Unfortunately it´l still take ~3,5 days/s of simulation (In my case it will be stopped after 30000s anyway).

The solver log now says that the velocity exceeds 500 m/s which ist way too fast. Expectation ist a maximum of less than 0,5 m/s at the inlet. Furthermore the Volume Ratio is 105. A.f.a.i.k. this should be below 100. I solved this by meshing again with “fine”, but didin´t yet run a simulation with this.

Besides the meshing, what else can I do to speed up simulation? I have to say that the Model is relatively large (I think). It´s a manhole (grid chamber) with 6m in diameter and comparable depth. The inlet and outlet is 1,8m in diameter each. Inflow is 0,775 m³/s. May this actually be too large for the utilised 16 cores max?

The moderate mesh ist still running. After finishing, I will start again with the fine mesh. Maybe I can add more information after the first timesteps.

I would be grateful for your Ideas.

I think you mesh is good enough, in terms of the small number of elements.

I don’t think there is much you can do to speed up the simulation, in this case you might be limited by the size of the machine you can access with the community account.