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Mohamed Farhat

Cette personne a quitté l’EPFL

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Publications associées (118)

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Virtual-versus-Real Implantation of Flow Diverters: Clinical Potential and Influence of Vascular Geometry

Mohamed Farhat, Pierre Bouillot

BACKGROUND AND PURPOSE: Intracranial stents have become extremely important in the endovascular management of complex intracranial aneurysms. Sizing and landing zone predictions are still very challenging steps in the procedure. Virtual stent deployment ma ...

American Society of Neuroradiology (ASNR)2016

Numerical study on the scale effect of tip vortex cavitation induced by incoming velocities and scale ratios

Mohamed Farhat

Large eddy simulations of tip vortex cavitation (TVC) around an elliptical hydrofoil is performed to study its scale effect. A satisfying agreement is obtained between the numerical and experimental data. It indicates that the scale effect of TVC is remark ...

PERGAMON-ELSEVIER SCIENCE LTD2023

Advanced Instrumentation for Measuring Fluid-Structure Coupling Phenomena in the Guide Vanes Cascade of a Pump-Turbine Scale Model

François Avellan, Mohamed Farhat, Vlad Hasmatuchi, Steven Roth

In the present study, the fluid-structure coupling is investigated in the guide vanes of a pump-turbine scale model placed in one of the test rigs of the Laboratory for Hydraulic Machines (EPFL) in Lausanne. The paper focuses on the advanced instrumentatio ...

American Soc Mechanical Engineers, Three Park Avenue, New York, Ny 10016-5990 Usa2010

How Flow Reduction Influences the Intracranial Aneurysm Occlusion: A Prospective 4D Phase-Contrast MRI Study

Mohamed Farhat, Philippe Reymond, Pierre Bouillot

BACKGROUND AND PURPOSE: Flow-diverter stents are widely used for the treatment of wide-neck intracranial aneurysms. Various parameters may influence intracranial aneurysm thrombosis, including the flow reduction induced by flow-diverter stent implantation, ...

American Society of Neuroradiology (ASNR)2019

Shock waves from nonspherical cavitation bubbles

Mohamed Farhat, Danail Obreschkow, Nicolas Dorsaz, Philipp Kobel, Marc Tinguely, Outi Supponen

We present detailed observations of the shock waves emitted at the collapse of single cavitation bubbles using simultaneous time-resolved shadowgraphy and hydrophone pressure measurements. The geometry of the bubbles is systematically varied from spherical ...

Amer Physical Soc2017

Experimental Investigation of Pressure Fluctuations in a High-Energy Centrifugal Pump Stage at Off-Design Conditions

François Avellan, Mohamed Farhat, Philippe Dupont

In centrifugal pumps, the interaction between the rotating impeller blades and the stationary diffuser vanes generates specific pressure fluctuation patterns. At off design operation, high incidence and large local pressure gradients can lead to flow separ ...

Institution of Mechanical Engineers2014

Mind the gap: a new insight into the tip leakage vortex using stereo-PIV

Mohamed Farhat, Cécile Münch-Alligné, Matthieu Dreyer

The tip leakage vortex (TLV), which develops in the clearance between the rotor and the stator of axial hydro turbines, has been studied for decades. Yet, many associated phenomena are still not understood. For instance, it remains unclear how the clearanc ...

Springer2014

Cavitation induction by projectile impacting on a water jet

Mohamed Farhat

The present paper focuses on the simulation of the high-velocity impact of a projectile impacting on a water-jet, causing the onset, development and collapse of cavitation. The simulation of the fluid motion is carried out using an explicit, compressible, ...

PERGAMON-ELSEVIER SCIENCE LTD2019

Techniques for generating centimetric drops in microgravity and application to cavitation studies

Mohamed Farhat, Philipp Kobel, Danail Obreschkow, Nicolas Dorsaz, Philippe Kobel

This paper describes the techniques and physical parameters used to produce stable centimetric water drops in microgravity, and to study single cavitation bubbles inside such drops (Parabolic Flight Campaigns, European Space Agency ESA). While the main sci ...

2009

High-speed imaging of high pressures produced by cavitation bubbles

Mohamed Farhat, Danail Obreschkow, Outi Supponen

Cavitation bubbles, when correctly tuned, may provide interesting mechanical and chemical effects to their surroundings owing to their violent collapse. Such an event may produce high-speed liquid jetting, extreme heating, as well as pressures of thousands ...

SPIE-INT SOC OPTICAL ENGINEERING2019

Neurovascular stent artifacts in 3D-TOF and 3D-PCMRI: Influence of stent design on flow measurement

Mohamed Farhat, Pierre Bouillot

Purpose: The morphological and hemodynamic evaluations of neurovascular diseases treated with stents would benefit from noninvasive imaging techniques such as 3D time-of-flight MRI (3D-TOF) and 3D phase contrast MRI (3D-PCMRI). For this purpose, a comprehe ...

WILEY2019

Mind the gap - tip leakage vortex in axial turbines

Mohamed Farhat, Matthieu Dreyer

The tendency of designing large Kaplan turbines with a continuous increase of output power is bringing to the front the cavitation erosion issue. Due to the flow in the gap between the runner and the discharge ring, axial turbine blades may develop the so ...

IOP Publishing2014

Gravity-Independent Oscillate Boiling

Mohamed Farhat, Outi Supponen

Heat transfer in nucleate boiling relies on the detachment and rise of the boiling bubble, in which gravity plays the dominant role. Previous studies showed that in the absence of gravity, the bubble fails to rise, causing the dryout of the heater and sign ...

SPRINGER2019

Effect of the winglet on reduction of blade tip vortex from elliptical hydrofoil

Mohamed Farhat, Azin Amini

It is well known that the performance of the turbomachinery (losses, vibrations, noise, and erosion) is often affected by the trailing vortex from the blade tip (Tip Leakage Vortex; TLV) of the impeller or propeller, and sometimes cavitation occurs in the ...

IOP Publishing2021

Determination of a scale-up factor from mixing time studies in orbitally shaken bioreactors

Christos Comninellis, Florian Maria Wurm, Mohamed Farhat, David Hacker

Efficient mixing in bioreactors is essential in order to avoid concentration gradients which can be harmful for mammalian cells. To study mixing and its scalability in orbitally shaken cylindrical bioreactors, we measured mixing times in containers with no ...

Elsevier2010

RANS computations of tip vortex cavitation

Mohamed Farhat, Matthieu Dreyer

Some two-dimensional (2D) exfoliated zeolites are single- or near single-unit cell thick silicates that can function as molecular sieves. Although they have already found uses as catalysts, adsorbents and membranes precise determination of their thickness ...

Institute of Physics2015

Cavitation in impacted drops and jets and the effect on erosion damage thresholds

Mohamed Farhat, Danail Obreschkow, Marc Tinguely

It is well known that metals and alloys erode at lower impact threshold velocities than expected. This was studied by Thomas and Brunton (1970) who reported “discrepancy factors” in the range 4–10. These authors suggested that liquid impact was a more sear ...

Elsevier Science Sa2012

Perfluorocarbon emulsion enhances MR-ARFI displacement and temperature in vitro: Evaluating the response with MRI, NMR, and hydrophone

Mohamed Farhat, Davide Bernardo Preso

Sonosensitive perfluorocarbon F(8)TAC(18)-PFOB emulsion is under development to enhance heating, increase thermal contrast, and reduce treatment times during focused ultrasound tumor ablation of highly perfused tissue. The emulsion previously showed enhanc ...

FRONTIERS MEDIA SA2023

Analysis of the dynamic response of pump-turbine runners- Part I: Experiment

François Avellan, Mohamed Farhat, Xiaopeng Huang

When in operation, pump-turbine runners have to withstand large pressure pulsations generated by the rotor-stator interaction. The analysis of the dynamic behavior of these structures is necessary to avoid damage. For this analysis a realistic model of the ...

International Association For Hydraulic Research2012

Observation of the Formation of Multiple Shock Waves at the Collapse of Cavitation Bubbles for Improvement of Energy Convergence

Mohamed Farhat, Marc Tinguely

The collapse of a cavitation bubble is always associated with the radiation of intense shock waves, which are highly relevant in a variety of applications. To radiate a strong shock wave, it is necessary to converge energy at the collapse, and understandin ...

MDPI2022