Publications de Mohamed Farhat

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Flow numerical simulations in a low specific speed radial pump-turbine scale model are performed to investigate off-design operating conditions in generating mode. The Best Efficiency Point (BEP) and the runaway operating conditions at 10° guide vanes open ...

In recent years, considerable interest has been devoted to the interactions between cavitation bubbles and tissue-mimicking materials due to their promising applications in medicine and biomedical sciences. The strong fluid-structure interaction between a ...

The present study deals with the shedding process of the Kármán vortices in the wake of a NACA0009 hydrofoil at high Reynolds number. This research addresses the effects of the foil leading edge roughness on the wake dynamic with a special focus on the vor ...

We present detailed visualizations of the micro-jet forming inside an aspherically collapsing cavitation bubble near a free surface. The high-quality visualizations of large and strongly deformed bubbles disclose so far unseen features of the dynamics inside the bubble, such as a mushroom-like flattened jet-tip, crown formation and micro-droplets. We also find that jetting near a free surface reduces the collapse time relative to the Rayleigh time.

A fluid engaging device comprising a vortex mitigating component configured for integration in, or for assembly to, a vortex inducing zone of the fluid engaging device, the vortex mitigating component (2) comprising a vortex reducing structure (3) comprising at least one network (5, 5a, 5b) of interconnected5 tortuous channels bounded by an outer boundary (4) having at least a first surface portion (4a) and a second surface portion (4b), the network of interconnected channel sections (6) extending between i

In 2009, l’Hydroptère broke the symbolic barrier of 50 knots and became the world fastest sailing boat over both 500 meters and 1 nautical mile. This major achievement relied on the high skills of the sailing team but also on technical advances of the boat, resulting from long years of studies and development. This achievement is also an open window to a new goal: flying around the world. In the present article, we present this long and incredible story, highlighting the different steps, the technology invo

The dynamic of a cavitation bubble inside a water drop is investigated in microgravity in order to analyze the interaction between the collapsing bubble and a quasispherical free surface. Tests are carried in the frame of the 42nd parabolic flight campaign ...

The present study concerns fluid-structure coupling phenomena occurring in a guide vane cascade of a pump-turbine scale model placed in the EPFL PF3 test rig. An advanced instrument set is used to monitor both vibrating structures and the surrounding flow. ...

Background and Purpose: Growth and rupture, the two events that dominate the evolution of an intracranial aneurysm, are both dependent on intraaneurysmal flow. Decrease of intraaneurysmal flow is considered an attractive alternative for treating intracrani ...

The phenomenon of vortex shedding behind a hydrofoil is an important issue from both scientific and technical point of view. The resulting fluctuating forces may lead to excessive vibrations and premature cracks in the hydraulic machines. According to prev ...

The first three mode shapes of a cantilevered NACA0009 hydrofoil were experimentally investigated in air and under different flow conditions in a cavitation tunnel. First and second bending modes and first torsion mode were determined in resonance conditio ...

In the present study, we have carried out an experimental investigation on the fluid-structure interaction caused by Karman vortices in the wake of a truncated 2D hydrofoil. The instrumentation involves a high frequency accelerometer and high speed visuali ...

We studied spark-generated shockwaves propagating inside stable water drops produced in microgravity. The closed and isolated liquid geometry results in a unique confinement of shockwaves, since the latter bounce of the free surface. This setting results in an amplified form of secondary cavitation, and proved particularly useful to study the coupling between shockwaves and secondary cavitation. High-speed visualizations and 3D computer simulations reveal that focus zones in the shockwave propagation lead t

The shedding process of the von Kármán vortices is shown to be highly related to the state of the boundary layer over the entire hydrofoil: The selected hydrofoil has a laminar-turbulent boundary layer transition at mid-chord for an incidence angle of 0° a ...

The aim of the paper is to present the results of investigations conducted on the free surface flow in a Pelton turbine model bucket. Unsteady numerical simulations, based on the two-phase homogeneous model, are performed together with wall pressure measur ...

This paper presents an experimental investigation of the vortex shedding in the wake of blunt and oblique trailing edge hydrofoils at high Reynolds number, Re=5 10 5 - 2.9 10 6. The velocity field in the wake is surveyed with the help of Particle-Image-Vel ...

The effect of hydrofoil trailing edge shape on the wake dynamic and flow induced vibration is investigated at high Reynolds number, Re = 0.5 x 10(6)-2.9 x 10(6). Two NACA 0009 hydrofoils with blunt and oblique trailing edges are tested. The velocity field ...

In the process of developing tools for cavitation erosion prediction of prototypes from mode) tests, 4 on board aggressiveness evaluation methods were tested on a severely eroded blade of a 266 MW Francis turbine. These are pressure, pit counting, DECER electrochemical and vibration measurements. All methods provided coherent results on the blade mounted measurements. The test program provided understanding of the heterogeneous erosion distribution of the prototype blades and quantitative data for compariso

Structure Interaction (FSI) phenomena is becoming a relevant study field for the design or revamping of hydropower plants. The generalized trend of increasing flow rates and reducing rotor blades/stay vanes thickness in order to improve the efficiency of t ...

The flow in the Pelton turbine bucket is three-dimensional, unsteady, turbulent, features a free surface, and is influenced by the rotation-induced forces. It is therefore difficult to investigate how the energy transfer takes place between the water flow ...

Mohamed Farhat

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Hydrodynamics of a Pump-Turbine at Off-Design Operating Conditions: Numerical Simulation

Cavitation bubble dynamics and microjet atomization near tissue-mimicking materials

Cavitation in Kármán Vortex Shedding from 2D Hydrofoil: Wall Roughness effects

Detailed Jet Dynamics in a Collapsing Bubble

Fluid engaging device with a vortex mitigating component

L'Hydroptère: A story of a dream

Interaction of a cavitation bubble with a spherical free surface

Fluid-Structure Coupling in the Guide Vanes Cascade of a Pump-Turbine Scale Model

Effect of Flow Diverter Porosity on Intra-aneurysmal Blood Flow

Vortex shedding from blunt and oblique trailing edge hydrofoils

Experimental mode shape determination of a cantilevered hydrofoil under different flow conditions

Cavitation effects on fluid-structure interaction in the case of a 2D hydrofoil

Secondary Cavitation and Shockwaves in Isolated Volumes

Hydrofoil Roughness Effects on von Kármán Vortex Shedding

Flow in a Pelton Turbine Bucket: Numerical and Experimental Investigations

Experimental investigation of the vortex shedding dynamic in the wake of oblique and blunt trailing edge hydrofoils using PIV-POD method

How oblique trailing edge of a hydrofoil reduces the vortex-induced vibration

Cavitation Erosion Prediction on Francis Turbines Part 1 : Measurements on the Prototype

Boundary layer effects on the vortex shedding in a Donaldson-type hydrofoil

Numerical Flow Analysis in a Pelton Turbine Bucket