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Cavitation bubles

2 REPLIES 2
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Message 1 of 3
javier101191
382 Views, 2 Replies

Cavitation bubles

Hello!

 

I have made a model where i forced water to cavitate. It is all ok, except that i dont know if the simulation simulates if the bubles created with cavitation "moves" following the water movement, or the bubles are only calcutated with the pressure vapour.

 

Thanks everyone.

2 REPLIES 2
Message 2 of 3
Jon.Wilde
in reply to: javier101191

Hi,

 

CFD is really only predicting where cavitation will occur (based on pressure as you say), rather than modelling the bubbles.

 

Hope that helps.

Jon

Message 3 of 3
heath.houghton
in reply to: Jon.Wilde

CFD doesn't show the bubbles, but it does show the region of cavitation with the vapor fraction.

Straight from the help system:
"The cavitation model tracks the vapor bubble volume fraction and predicts the onset and location of bubble formation within the flow. It is best suited for predicting small regions of cavitation, and does not predict large vapor formations. This cavitation model assumes a collection of bubbles and not a total vapor region.

When cavitation is enabled, the fluid pressure does not fall below the vapor pressure. (If cavitation is disabled, the pressure is allowed to fall below the physical limit.) This improves the accuracy of forces computed by the Wall Calculator when cavitation is present."

So for small amounts of cavitation, the cavitation model helps identify regions of cavitation, give more accurate fluid pressure drops and more accurate wall forces than if you didn't enable cavitation. You can look at scalar to identify the cavitation regions and their severity. The most important thing to recognize is if the cavitation region grows too large, it can go beyond the scope of the capability and cause instability.

Heath


Heath Houghton
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