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Cavitiy Length for NPSHi calculation

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Old   October 5, 2022, 04:12
Default Cavitiy Length for NPSHi calculation
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Daniel
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Hello,

is there a way to calculate the cavity length in a pump simulation with the cavitation model ?
I would even like to stop the solver when a certain cavity length has been reached, so I can calculate the NPSHi for a given flow.

I tried to work with IsoClips in CFD Post and use the length expression, but that is not very clear to me, wether this is a correct or suitable approach.
Has anybody done this before ?

Thank you your help!
Daniel
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Old   October 8, 2022, 04:14
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Glenn Horrocks
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If you define an isosurface of volume fraction you can get the volume which has gone to vapour. But you will need to define how you want to convert that volume to a length - possible approaches could be maximum extent in x, y z, or a specific direction; longest extent; cube root of the volume - or maybe some other definition is suitable for your case.
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Old   October 10, 2022, 02:44
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Thank you, Glenn!
Indeed it worked with the Volume Fraction.
I created a polyline on the hub and shroud (later additional lines from hub to shroud) and plotted the "Curve Length" of that polyline and calcualted the length where the volume fraction is greater than zero.
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