Publications by Jacques Rappaz

A mixture model for a dilute dispersion of gas in a liquid flow: Mathematical analysis and application to aluminium electrolysis

Jacques Rappaz, Marco Picasso, Emile Tryphon Pierre Soutter

A mixture model to take into account the flow of small carbon dioxide bubbles dissolved in a liquid is presented. The model describes the evolution of the velocity fields (mixture and gas), the pressure and the volume fraction of gas. The system of equatio ...

2021

On Von Karman Modeling For Turbulent Flow Near A Wall

Jacques Rappaz, Jonathan Rochat

Mixing-length models are often used by engineers in order to take into account turbulence phenomena in a flow. This kind of model is obtained by adding a turbulent viscosity to the laminar one in Navier-Stokes equations. When the flow is confined between t ...

2019

Conservation Schemes For Convection-Diffusion Equations With Robin Boundary Conditions

Jacques Rappaz, Stéphane Flotron

In this article, we present a numerical scheme based on a finite element method in order to solve a time-dependent convection-diffusion equation problem and satisfy some conservation properties. In particular, our scheme is able to conserve the total energ ...

EDP Sciences2013

Numerical simulation of two-phase flow with interface tracking by adaptive Eulerian grid subdivision

Jacques Rappaz, Alexandre Caboussat, Pascal Clausen

A numerical model for the simulation of three-dimensional liquid-gas flow with free surfaces is presented. The incompressible Navier-Stokes equations are assumed to hold in the liquid domain, while the surrounding gas is assumed to be compressible, with co ...

2012

Modelling and mathematical results arising from ferromagnetic problems

Jacques Rappaz, Michel Flück, Jean Descloux

In this article, we investigate the equations of magnetostatics for a configuration where a ferromagnetic material occupies a bounded domain and is surrounded by vacuum. Furthermore, the ferromagnetic law takes the form ...

SP Science China Press, Springer2012

Modelling and Numerical Simulation of the Dynamics of Glaciers Including Local Damage Effects

Jacques Rappaz, Marco Picasso, Martin Funk

A numerical model to compute the dynamics of glaciers is presented. Ice damage due to cracks or crevasses can be taken into account whenever needed. This model allows simulations of the past and future retreat of glaciers, the calving process or the break- ...

2011

Existence and stability of steady-state solutions of the shallow-ice-sheet equation by an energy-minimization approach

Jacques Rappaz, Guillaume Jouvet, Heinz Blatter

The existence of solutions of the non-sliding shallow-ice-sheet equation on a flat horizontal bed with a mass balance linearly depending on altitude is proven for fixed margins. Free-margin solutions for the same mass balance do not exist. Fixed-margin sol ...

International Glaciological Society2011

Optimization Problem Coupled with Differential Equations: A Numerical Algorithm Mixing an Interior-Point Method and Event Detection

Jacques Rappaz, Alexandre Caboussat, Christian Landry

The numerical analysis of a dynamic constrained optimization problem is presented. It consists of a global minimization problem that is coupled with a system of ordinary differential equations. The activation and the deactivation of inequality constraints ...

2010

Scientific Computing For Aluminum Production

Jacques Rappaz, Marco Picasso, Michel Flück, Gilles Steiner, Thomas Hofer

Numerical simulation in aluminum production envolves many different topics, this paper is dedicated to some aspects of two of them. In the first part, a numerical approach for the computation of the motion of the fluids in an electrolitic cell is presented ...

2009

Numerical simulation of thermal problems coupled with magnetohydrodynamic effects in aluminium cell

Jacques Rappaz, Michel Flück

A system of partial differential equations describing the thermal behavior of aluminium cell coupled with magnetohydrodynamic effects is numerically solved. The thermal model is considered its a two-phases Stefan problem which consists of a non-linear conv ...

Elsevier2009