The energy problem when solving cavitation in FLUENT

javat33489 · December 30, 2023, 13:06

Hi all.
I am simulating the operation of a centrifugal pump.
I did the calculations on the water, everything is fine.
Previously, I saw a tutorial on HOW TO from ANSYS:

https://www.youtube.com/embed/bgdBrOBuNgQ

and my settings are also the same, inlet pressure and outlet mass flow.

Next, I need to calculate cavitation, I also paid attention to the video from ANSYS:

https://www.youtube.com/watch?v=9E3Q-cqhkVw

My settings are the same again.

My problem is that the calculation starts and the energy and continuity grow greatly, which leads to an error:

I tried all the settings but nothing helps (changed methods, reduced relaxation coefficients, switched to stationary mode + pseudo transient, changed turbulence options k-e, k-omega, etc.).
I used substep time steps of 0.001, it seems that this is not enough. I made a new calculation with a step of 1e-5, it was very long and left it to be decided further, the graph is already like this:

Can this help? Should you take an even smaller step? The calculation will take even longer, I'm using 48 cores.
Thank you.

lolno · January 5, 2024, 11:18

do you mind showing a cross section of your mesh? and how's your mesh quality metrics?

December 30, 2023, 13:06	The energy problem when solving cavitation in FLUENT	#1
javat33489 New Member Rasl Join Date: Dec 2023 Location: India Posts: 6 Rep Power: 2	Hi all. I am simulating the operation of a centrifugal pump. I did the calculations on the water, everything is fine. Previously, I saw a tutorial on HOW TO from ANSYS: https://www.youtube.com/embed/bgdBrOBuNgQ and my settings are also the same, inlet pressure and outlet mass flow. Next, I need to calculate cavitation, I also paid attention to the video from ANSYS: https://www.youtube.com/watch?v=9E3Q-cqhkVw My settings are the same again. My problem is that the calculation starts and the energy and continuity grow greatly, which leads to an error: I tried all the settings but nothing helps (changed methods, reduced relaxation coefficients, switched to stationary mode + pseudo transient, changed turbulence options k-e, k-omega, etc.). I used substep time steps of 0.001, it seems that this is not enough. I made a new calculation with a step of 1e-5, it was very long and left it to be decided further, the graph is already like this: Can this help? Should you take an even smaller step? The calculation will take even longer, I'm using 48 cores. Thank you.

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January 5, 2024, 11:18		#2
lolno New Member Join Date: Aug 2019 Posts: 12 Rep Power: 7	do you mind showing a cross section of your mesh? and how's your mesh quality metrics?