Second viscosity in transient cavitating pipe flows

The paper presents the results of a research on the use of distributed cavitation quasi-2D models to reproduce experimental runs of cavitating water hammer flow. Two effects due to presence of free gas are taken into account: the first is the dependence of the wavespeed on the pressure; the second is the presence of additional dissipations due to thermodynamic interactions between liquid and free gas or to dissolved gas release phenomena. For the latter aspects, different formulations of bulk viscosity (or second viscosity) coefficient are taken into account and verified by comparison with experimental results of cavitating water hammer flow. The comparison between computed and measured head oscillations show that the model allows a good reproduction of the observed phenomena if a proper calibration of the parameters is made.