Figure 5
From: Turbulence and Cavitation Suppression by Quaternary Ammonium Salt Additives
Computational domain and numerical results showing the effect of viscoelasticity on the nozzle flow and cavitation. (a) Computational domain, the blue rectangle indicates the flow visualization region, nozzle dimensions given in mm, (b,c) show the cavitation structures (dark colour) and vortex structures (translucent red color) in the nozzle for the Newtonian and the viscoelastic fluid, cavitation structures are presented by isosurface of 50% vapour volume fraction and vortex structures are presented by isosurface of second invariant of the velocity gradient at 2 × 109 s−2, (d,e) time averaged vapour volume fraction in the mid-plane of the nozzle, cavitation suppression by viscoelasticity is particularly visible close to the nozzle wall where the cavity cloud is clearly detached from the wall, (f) time-averaged streamwise velocity at the nozzle exit, it is evident that the velocity is enhanced by the viscoelastic fluid, (g) RMS of velocity fluctuations at the nozzle exit, viscoelasticity can supress turbulence and reduce the level of velocity fluctuations.
