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Professor Parviz Moin, Director of the Center for Turbulence Research
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Two problems with subgrid modelling: Contact line dynamics and mass transfer in a ladle

Professor Stéphane Zaleski, Institut Jean Le Rond d’Alembert, Sorbonne Université

Event Details:

Wednesday, April 10, 2024
11:00am - 12:00pm PDT

Location

CTR Conference Room

Contact

This event is open to:

Faculty/Staff
Students

Abstract 

Among the most difficult issues in CFD is the very wide range of scales involved in a wide range of problems.  Attempts at investigating the contact line problem have been made coming from various theoretical and numerical frameworks, the closest to first principles being molecular dynamics, while diffuse interface methods and sharp interface methods with several variants have also been put forward. Experiments are obviously difficult.  Efforts made on a number of typical cases, including plunging and withdrawing plates, a sheared droplet, sessile droplets on oscillating or accelerating substrates, menisci in nanopores and the hydrodynamics assist problem. The issues involved in nucleate boiling and accelerated sessile droplets will be addressed both from the point of view of experiments (performed by various colleagues from MIT and Tokyo University) and from the point of view of simulations.   To model the ladle metallurgical secondary refinement process, a container of water, modelling the molten metal, is topped by a thin layer of oil, modelling the slag. The system is agitated by the injection of air at the bottom, creating a bubble plume that merges into the air at the top of the system. Theoretical, numerical, and experimental studies of the hydrodynamic properties of the system are performed. The rising bubble form a vertical plume akin to thermal plumes and following similar (Q/z)-1/3 scaling, where Q is the flow rate. Results are compared by a measurement often used in the literature, the area of “open eye” arising at the center of the oil layer, and the mass transfer measured at different flow rates. The Reynolds number is large but does not exceed values at which Direct Numerical Simulation remains possible.  On the other hand, the simulation is made difficult by the large value of the Schmidt number, a difficulty attacked using a subgrid model.

Short Bio

Stéphane Zaleski is Professor of Mechanics at Sorbonne Université and member of the “Institut Jean Le Rond d’Alembert”. After early years at the Physics Laboratory of Ecole Normal Supérieure in Paris where he obtained his PhD under the supervision of Yves Pomeau, and three years at the applied math group of MIT he joined the Mechanics group at University of Paris 6, aka UPMC, now merged into Sorbonne Université. He investigates numerical methods for multiphase flows with applications to atomization, cavitation, porous media flow, nucleate boiling, hydrometallurgy, moving contact lines and droplet impact, including several variants of the Volume of Fluid method, the Edge-Based Interface Tracking method and the Diffuse Interface method. He has written several computer codes for the simulation of multiphase flow including PARIS Simulator (with D. Fuster, Y. Ling, R. Scardovelli and G. Tryggvason) and is involved in the development of the basilisk platform. He is Associate Editor of J. Comput. Phys. and of Computers and Fluids. He leads the ERC-Advanced project TRUFLOW on mass transfer at large Schmidt numbers and is a member of Institut Universitaire de France.

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