Jalel Chergui - Academia.edu (original) (raw)

Papers by Jalel Chergui

Journal of Biomechanical Engineering

Ureteroscopy is a commonly performed medical procedure to treat stones in the kidney and ureter u... more Ureteroscopy is a commonly performed medical procedure to treat stones in the kidney and ureter using a ureteroscope. Throughout the procedure, saline is irrigated through the scope to aid visibility and wash-out debris from stone fragmentation. The key challenge that this research addresses is to build a fundamental understanding of the interaction between the kidney stones/stone fragments and the flow dynamics in the renal pelvis flow. We examine the time-dependent flow dynamics inside an idealized renal pelvis in the context of a surgical procedure for kidney stone removal. Here, we examine the time-dependent evolution of these vortical flow structures in three dimensions, and incorporate the presence of rigid kidney stones. We perform direct numerical simulations, solving the transient Navier–Stokes equations in a spherical domain. Our numerical predictions for the flow dynamics in the absence of stones are validated with available experimental and numerical data, and the govern...

Physics of Fluids

In this study, we investigate the energy conversion and dissipation mechanisms of spreading dropl... more In this study, we investigate the energy conversion and dissipation mechanisms of spreading droplets on a solid surface at a low Weber number regime, which neither conventional energy-balance-based theories nor empirical scaling laws can completely explain. The energetic analysis presented in this study shows that on a hydrophilic surface, the actual primary energy source driving the spreading process is the initial surface energy not the initial kinetic energy. The conventional energy-balance-based approaches are found to be valid only for the spreading process on a hydrophobic surface. Particular attention is also paid to the roles of the capillary waves. The capillary waves are found to play significant roles in all of the important flow physics, that is, the interfacial structure, the oscillatory motions and the rapid collapse of the liquid film, the onset of the viscous regime, and the energy loss mechanism. It is also shown that the energy dissipation caused by the capillary-w...

75th Annual Meeting of the APS Division of Fluid Dynamics - Gallery of Fluid Motion

Bulletin of the American Physical Society, 2016

London-The dynamics of a thin film falling down an inclined solid surface have attracted the atte... more London-The dynamics of a thin film falling down an inclined solid surface have attracted the attention of many researchers because of the richness and variety of waves which develop on its liquid-air interface. Besides experimental work, the problem has been widely studied in the literature but direct numerical simulations have been limited to two-dimensions or low-dimensional modeling for three-dimensional problems. We present a computational study of falling liquid films in a three-dimensional inclined rectangular domain (45 •) using the massively parallel code BLUE for Lagrangian tracking of arbitrarily deformable phase interfaces. Calculations are carried out on O(10 3) cores in a large domain (24cm × 12cm × 1.5 cm) for Reynolds and Kapitza numbers of 100 and 10, respectively, in order to obtain several three-dimensional wave patterns and solitary waves.

74th Annual Meeting of the APS Division of Fluid Dynamics - Gallery of Fluid Motion, 2021

Le Centre pour la Communication Scientifique Directe - HAL - Diderot, Dec 1, 2016

APS Division of Fluid Dynamics Meeting Abstracts, 2020

APS Division of Fluid Dynamics Meeting Abstracts, Nov 1, 2017

Bulletin of the American Physical Society, Nov 22, 2021

Bulletin of the American Physical Society, Nov 22, 2021

APS Division of Fluid Dynamics Meeting Abstracts, Nov 1, 2019

Bulletin of the American Physical Society, 2016

Bulletin of the American Physical Society, 2019

Bulletin of the American Physical Society, 2020

breakup of an interface into a cascade of droplets and their subsequent coalescence is a generic ... more breakup of an interface into a cascade of droplets and their subsequent coalescence is a generic problem of central importance to a large number of industrial settings such as mixing, separations, and combustion. Therefore, it is unsurprising that the breakup of liquid jets during injection (i.e. atomisation) has received great scientific interest, and this is the focus of this study. We use a hybrid interface-tracking/levelset method to treat the surface tension forces of the Navier-Stokes equations in a three-dimensional Cartesian domain. A turbulent water jet is gradually injected through a cylindrical nozzle into the computational domain, which is filled with a stagnant viscous oil. The atomisation induces the formation of outer and inner lobes which film thickness reduces overtime to generate holes. Those holes expand radially driven by surface tension to form ligaments, and subsequently droplets. The formation of the lobes can be explained though through its vortex-surface interaction. A full parametric study is presented, and the relevant mechanisms underlying the flow phenomena are elucidated.

Bulletin of the American Physical Society, 2016

Bulletin of the American Physical Society, 2015

Bulletin of the American Physical Society, 2015

PMD (Parallel Multi-Domain decomposition) is a set of Fortran 90 modules which implements a paral... more PMD (Parallel Multi-Domain decomposition) is a set of Fortran 90 modules which implements a parallel none-overlapping domain decomposition method based on the so called dual- Schur complement. The Schur matrix is built using an inuenc e matrix technique. In this paper, we will briey describe the implementation. A case study will then be presented and performance results will be shown on three parallel machines: IBM SP2, SGI/CRAY T3E-600 and Fujitsu VPP300. At the end, the public location of PMD will be given together with the installation procedure. MOTS-CL ES : performance, parall ele, elliptique, lin eaire, second ordre, d ecomposition de domaine, compl ement de Schur, matrice d'inuenc e, PMD, SP2, T3E, VPP300, LAPACK, ScaLAPACK, MPI

Bulletin of the American Physical Society, 2015

Journal of Biomechanical Engineering

Ureteroscopy is a commonly performed medical procedure to treat stones in the kidney and ureter u... more Ureteroscopy is a commonly performed medical procedure to treat stones in the kidney and ureter using a ureteroscope. Throughout the procedure, saline is irrigated through the scope to aid visibility and wash-out debris from stone fragmentation. The key challenge that this research addresses is to build a fundamental understanding of the interaction between the kidney stones/stone fragments and the flow dynamics in the renal pelvis flow. We examine the time-dependent flow dynamics inside an idealized renal pelvis in the context of a surgical procedure for kidney stone removal. Here, we examine the time-dependent evolution of these vortical flow structures in three dimensions, and incorporate the presence of rigid kidney stones. We perform direct numerical simulations, solving the transient Navier–Stokes equations in a spherical domain. Our numerical predictions for the flow dynamics in the absence of stones are validated with available experimental and numerical data, and the govern...

Physics of Fluids

In this study, we investigate the energy conversion and dissipation mechanisms of spreading dropl... more In this study, we investigate the energy conversion and dissipation mechanisms of spreading droplets on a solid surface at a low Weber number regime, which neither conventional energy-balance-based theories nor empirical scaling laws can completely explain. The energetic analysis presented in this study shows that on a hydrophilic surface, the actual primary energy source driving the spreading process is the initial surface energy not the initial kinetic energy. The conventional energy-balance-based approaches are found to be valid only for the spreading process on a hydrophobic surface. Particular attention is also paid to the roles of the capillary waves. The capillary waves are found to play significant roles in all of the important flow physics, that is, the interfacial structure, the oscillatory motions and the rapid collapse of the liquid film, the onset of the viscous regime, and the energy loss mechanism. It is also shown that the energy dissipation caused by the capillary-w...

75th Annual Meeting of the APS Division of Fluid Dynamics - Gallery of Fluid Motion

Bulletin of the American Physical Society, 2016

London-The dynamics of a thin film falling down an inclined solid surface have attracted the atte... more London-The dynamics of a thin film falling down an inclined solid surface have attracted the attention of many researchers because of the richness and variety of waves which develop on its liquid-air interface. Besides experimental work, the problem has been widely studied in the literature but direct numerical simulations have been limited to two-dimensions or low-dimensional modeling for three-dimensional problems. We present a computational study of falling liquid films in a three-dimensional inclined rectangular domain (45 •) using the massively parallel code BLUE for Lagrangian tracking of arbitrarily deformable phase interfaces. Calculations are carried out on O(10 3) cores in a large domain (24cm × 12cm × 1.5 cm) for Reynolds and Kapitza numbers of 100 and 10, respectively, in order to obtain several three-dimensional wave patterns and solitary waves.

74th Annual Meeting of the APS Division of Fluid Dynamics - Gallery of Fluid Motion, 2021

Le Centre pour la Communication Scientifique Directe - HAL - Diderot, Dec 1, 2016

APS Division of Fluid Dynamics Meeting Abstracts, 2020

APS Division of Fluid Dynamics Meeting Abstracts, Nov 1, 2017

Bulletin of the American Physical Society, Nov 22, 2021

Bulletin of the American Physical Society, Nov 22, 2021

APS Division of Fluid Dynamics Meeting Abstracts, Nov 1, 2019

Bulletin of the American Physical Society, 2016

Bulletin of the American Physical Society, 2019

Bulletin of the American Physical Society, 2020

breakup of an interface into a cascade of droplets and their subsequent coalescence is a generic ... more breakup of an interface into a cascade of droplets and their subsequent coalescence is a generic problem of central importance to a large number of industrial settings such as mixing, separations, and combustion. Therefore, it is unsurprising that the breakup of liquid jets during injection (i.e. atomisation) has received great scientific interest, and this is the focus of this study. We use a hybrid interface-tracking/levelset method to treat the surface tension forces of the Navier-Stokes equations in a three-dimensional Cartesian domain. A turbulent water jet is gradually injected through a cylindrical nozzle into the computational domain, which is filled with a stagnant viscous oil. The atomisation induces the formation of outer and inner lobes which film thickness reduces overtime to generate holes. Those holes expand radially driven by surface tension to form ligaments, and subsequently droplets. The formation of the lobes can be explained though through its vortex-surface interaction. A full parametric study is presented, and the relevant mechanisms underlying the flow phenomena are elucidated.

Bulletin of the American Physical Society, 2016

Bulletin of the American Physical Society, 2015

Bulletin of the American Physical Society, 2015

PMD (Parallel Multi-Domain decomposition) is a set of Fortran 90 modules which implements a paral... more PMD (Parallel Multi-Domain decomposition) is a set of Fortran 90 modules which implements a parallel none-overlapping domain decomposition method based on the so called dual- Schur complement. The Schur matrix is built using an inuenc e matrix technique. In this paper, we will briey describe the implementation. A case study will then be presented and performance results will be shown on three parallel machines: IBM SP2, SGI/CRAY T3E-600 and Fujitsu VPP300. At the end, the public location of PMD will be given together with the installation procedure. MOTS-CL ES : performance, parall ele, elliptique, lin eaire, second ordre, d ecomposition de domaine, compl ement de Schur, matrice d'inuenc e, PMD, SP2, T3E, VPP300, LAPACK, ScaLAPACK, MPI

Bulletin of the American Physical Society, 2015