Computational modelling of cavitation in simple geometries, but complex flows

conference paper

English

Cavitation occurs when local pressure in flowing liquid drops below saturated vapor pressure. If the resulting vapor bubbles are transported to regions of higher pressure then sudden condensation follows, which is accompanied by emission of pressure and acoustic waves. Above described process leads to cavitation erosion and consequently to shorter service time of the hydraulic machines. Cavitation can be modeled by current CFD tools with simplified cavitation models. Computational simulations revealed that proper capturing of the underlying one-phase flow field is crucial to obtain correct vorticity distribution. Clouds filled with vapor are born from regions of concentrated vorticity and shed downstream. Only advanced turbulence models (Reynolds Stress Model, Scale Adaptive Simulation) are able to predict vorticity field and development of the unsteady swirling flow. Increased vorticity generation in two-phase flows is caused by additional term in vorticity equation - baroclinic torque. Present paper dicusses relative magnitude of vorticity generation terms for cases of concentrated vortical structure and separated boundary layer over hydrofoil.

cavitation, vorticity, baroclinic torque

RUDOLF, P.; KOZÁK, J.

2014

3. 11. 2014

FAV ZČU Plzeň

Plzeň

978-80-261-0429-2

Computational mechanics 2014; book of extended abstracts

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