Sur la modélisation des écoulements multiphasiques compressibles

• Rémi Abgrall

A numerical strategy for 3D computations of shock-induced bubble collapse

• Ksenia Kozhanova

Modeling the cavitation phenomenon in spacecraft turbopumps: a two-phase flow approach

• Joris Cazé

Challenges in the computations of hydrodynamic cavitating flows

• Jean Decaix

High performance computing of bubble collapse on heterogeneous supercomputer

• Philippe Parnaudeau (Institut P')

Turbulence et cavitation, l’interaction de deux phénomènes complexes

• Henda Djeridi (LEGI, G-INP)

La question de savoir dans quelle mesure la turbulence contribue ou non à la modification des conditions d’apparition du changement de phase est très délicate. Le caractère multi-échelle de la turbulence ne permet pas de corréler les fréquences relatives d’une bulle à celle des structures tourbillonnaires présentes dans l’écoulement. Pour permettre de mieux appréhender l’ampleur de ces éventuelles interactions de nombreuses approches expérimentales ont été choisies et on en présente ici deux d’entre elles : • L’étude de l’influence de la présence de la phase vapeur sur la dynamique d’un écoulement de marche descendante à haut nombre de Reynolds • L’étude du comportement hydrodynamique et cavitant d’un corps profilé en mouvement d’oscillation Dans cet objectif, des actions collaboratives ont permis de déboucher sur des expériences dédiées pouvant être qualifiées de cas tests de référence pour une approche coordonnée afin de faire progresser la modélisation physique diphasique et de la modélisation numérique associée (compressible et/ou incompressible).

On the direction of jets during the the collapse of a bubble in contact with a rigid wall

• Daniel Fuster (CNRS Sorbonne Université)

In this work we will show that the dynamics of a bubble in contact with a wall is markedly different depending on the effective contact angle at the instant of maximum expansion. For contact angles smaller than 90 degrees, a classical jet develops towards the wall that generates large pressures upon its impact on the wall. For contact angles larger than 90 degrees, a re-entrant jet is observed that leads to an unconventional jet directed outwards the wall. This change of behavior can be explained using the solution of the potential flow around the bubble at small times. This solution is indeed singular at the contact line for contact angles larger than 90 degrees only. Direct Numerical Simulations will be used to unveil the importance of the the bubble shape at the instant of maximum radius on the effects induced by the bubble collapse in its surroundings and the peak pressures and temperatures reached.

Numerical investigation of sheet cavitation dynamics on a Venturi configuration

• Camille Gouin

Turbulent cavitation in a microchannel

• Denis Funfschilling (ICube)
• N. Rimbert
• G. Castanet

Modélisation et simulation diphasique compressible

• Kevin SCHMIDMAYER (INRIA Pau )

On the physical mechanism of tip vortex cavitation hysteresis

• Ali Amini (HES-SO)

Inception and desinence thresholds of tip vortex cavitation (TVC), generated by an elliptical NACA 16-020 hydrofoil, are measured at different flow conditions for various gas contents. It is observed that TVC often disappears at cavitation indices significantly higher than the inception thresholds introducing large hystereses. Our measurements reveal that TVC desinence pressure increases with gas content and, under specific flow conditions, may reach to atmospheric pressure. When the pressure of the cavitating core is below the initial saturation pressure of the dissolved gases, water flowing adjacent to the interface becomes supersaturated, which leads to the diffusion of air molecules into TVC. To estimate the outgassing rate, a simple diffusion model is proposed and analytically solved. In addition, we demonstrate that the extent of the delay in desinence due to outgassing is also dictated by the bulk flow parameters, i.e., the incidence angle and freestream velocity. Owing to flow visualizations, we assert that formation of a laminar separation bubble of appropriate size and shape at the hydrofoil tip is a necessary condition for a delayed desinence.

Experimental study of cavitation unsteadiness and erosion on a plane convex hydrofoil

• Luis Carlos Morocho Rosero