Workshop on Cavitation, bubble collapse and mass transfer

31 mai 2022, 09:00 → 1 juin 2022, 17:00 Europe/Paris

IRMA, université de Strasbourg

Objective of the workshop

Cavitation occurs in a variety of fluids and technologies such as engine combustion, rocket
engine, lubrication, marine propulsion, hydraulic pumps and turbines, medical applications, cleaning
water, chemical procedia. In most cases, the apparition of cavitation leads to several drawbacks and damages (erosion, vibration, efficiency decrease, head drop, noise, etc

This workshop marks the end of the ASCA project, the French ANR-18-CE46-0009-03 project : Advanced numerical Simulation for CAvitation: HPC, numerical and physical modelling, non equilibrium thermodynamics, large scale simulation.

In this workshop, we will address the physics and the modelling of cavitating flows, bubble collapse and mass transfer. The goal is to share physical mechanism comprehension, modelling methods, difficulties, (rigorous or more phenomenological) analysis, allowing the description of multiphase flows with mass transfer.

 

Program

 

The talks will start the morning of Tuesday 31 noon and finish Wednesday 1. The workshop follows the
Fourth Workshop on Compressible Multiphase Flows.

Keynote Speakers

Henda Djeridi, LEGI
Turbulence et cavitation, l’interaction de deux phénomènes complexes

Kevin Schmidmayer
Modélisation et simulation diphasique compressible

Rémi Abgrall, UZH - Institute of Mathematics
Sur la modélisation des écoulements multiphasiques compressibles

Contributions

Authors are invited to submit a title and a short abstract of their contribution. The presentation will be 20 minutes long plus 5 minutes of question. There are no fees registration but registration (authors and participants) is mandatory.

Practical informations

Location
Institut de Recherche Mathématique Avancée, Strasbourg (map).

Restaurant
Nous aurons rendez-vous le mardi 31 Mai au restaurant La Maison Kammerzell, Place de la cathédrale, Strasbourg (map).

Organizing committee

Yannick Hoarau and Eric Goncalves

 

 

mardi 31 mai

12:00 → 14:00 Repas

14:00 → 15:00 Sur la modélisation des écoulements multiphasiques compressibles

Orateur: Prof. Rémi Abgrall

15:00 → 15:30 A numerical strategy for 3D computations of shock-induced bubble collapse

Orateur: Dr Ksenia Kozhanova

15:30 → 16:00 Modeling the cavitation phenomenon in spacecraft turbopumps: a two-phase flow approach

Orateur: Joris Cazé

16:00 → 16:30 Pause Café

16:30 → 17:00 Challenges in the computations of hydrodynamic cavitating flows

Orateur: Dr Jean Decaix

17:00 → 17:30 High performance computing of bubble collapse on heterogeneous supercomputer

Orateur: Dr Philippe Parnaudeau (Institut P')

mercredi 1 juin

09:15 → 10:15 Turbulence et cavitation, l’interaction de deux phénomènes complexes

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).

Orateur: Prof. Henda Djeridi (LEGI, G-INP)

10:15 → 10:45 Pause Café

10:45 → 11:15 On the direction of jets during the the collapse of a bubble in contact with a rigid wall

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.

Orateur: Daniel Fuster (CNRS Sorbonne Université)

11:15 → 11:45 Numerical investigation of sheet cavitation dynamics on a Venturi configuration

Orateur: Camille Gouin

11:45 → 12:05 Turbulent cavitation in a microchannel

Orateurs: Dr Denis Funfschilling (ICube), Dr G. Castanet, Dr N. Rimbert

12:05 → 14:00 Repas

14:00 → 15:00 Modélisation et simulation diphasique compressible

Orateur: Dr Kevin SCHMIDMAYER (INRIA Pau )

15:00 → 15:30 On the physical mechanism of tip vortex cavitation hysteresis

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.

Orateur: Dr Ali Amini (HES-SO)

15:30 → 16:00 Experimental study of cavitation unsteadiness and erosion on a plane convex hydrofoil

Orateur: M. Luis Carlos Morocho Rosero