Concept

Sonochemistry

Related publications (11)

Advanced imaging and cavitation bubbles as promising tools for hemodynamic disorders diagnosis and treatment

Hemodynamic disorders encompass all anomalies occurring within blood vessels that disrupt the normal blood flow. Detecting these pathologies, assessing their severity, and evaluating the benefit-risk balance of associated treatments are essential for refining medical decision-making. In this context, the precise measurement of key parameters related to specific pathologies, as well as the understanding of physical phenomena involved in various endovascular intervention techniques and their complications, is

EPFL2025

RANS computations of a confined cavitating tip-leakage vortex

Mohamed Farhat, Matthieu Dreyer

Cavitating tip-leakage vortices appear in several hydrodynamic flows such as marine propellers or Kaplan turbines. Cavitating computations are a challenging topic since several keys issues are an ongoing work such as the definition of a universal mass sour ...

2018

Dynamics of the precessing vortex rope and its interaction with the system at Francis turbines part load operating conditions

François Avellan, Arthur Tristan Favrel, Christian Landry, Andres Müller, Keita Yamamoto, Joao Gomes Pereira Junior

At part load conditions, Francis turbines experience the formation of a cavitation vortex rope at the runner outlet whose precession acts as a pressure excitation source for the hydraulic circuit. This can lead to hydro-acoustic resonances characterized by ...

2017

Unsteady hydraulic simulation of the cavitating part load vortex rope in Francis turbines

François Avellan, Arthur Tristan Favrel

For Francis turbines at part load operation a helical vortex rope is formed due to the swirling nature of the flow exiting the runner. This vortex creates pressure fluctuations which can lead to power swings, and the unsteady loading can lead to fatigue da ...

2017

X-Ray Diffraction Observations of a Charge-Density-Wave Order in Superconducting Ortho-II YBa_{2}Cu_{3}O_{6.54} Single Crystals in Zero Magnetic Field

X-ray diffraction measurements show that the high-temperature superconductor YBa2Cu3O6.54, with ortho-II oxygen order, has charge-density-wave order in the absence of an applied magnetic field. The dominant wave vector of the charge density wave is q(CDW) = (0, 0.328(2), 0.5), with the in-plane component parallel to the b axis (chain direction). It has a similar incommensurability to that observed in ortho-VIII and ortho-III samples, which have different dopings and oxygen orderings. Our results for ortho-I

Amer Physical Soc2013

The most spherical cavitation bubble

Focusing a high energy pulsed laser into water is a widely used method to generate a single cavitation bubble. Such a bubble is generally assumed to collapse spherically. However, the precision of the focusing system and the effect of gravity, most often neglected, break the spherical symmetry of the collapse. In the experiment presented here, we generated the ‘most spherical’ cavitation bubbles in a series of experiments by (1) running the experiments in microgravity (during the 52nd ESA Parabolic Flight C

American Physical Society2011

Universal Scaling Law for Jets of Collapsing Bubbles

Mohamed Farhat, Danail Obreschkow

Cavitation bubbles collapsing and rebounding in a pressure gradient del p form a "microjet" enveloped by a "vapor jet." This Letter presents unprecedented observations of the vapor jets formed in a uniform gravity-induced del p, modulated aboard parabolic flights. The data uncover that the normalized jet volume is independent of the liquid density and viscosity and proportional to zeta equivalent to vertical bar del p vertical bar R-0/Delta p, where R-0 the maximal bubble radius and Delta p is the driving p

2011

Direct effects of gravity on cavitation bubble collapse

Mohamed Farhat, Danail Obreschkow, Philippe Kobel

We propose an experiment for studying the final stages of collapse of a single laser generated cavitation bubble in microgravity. Unlike previous investigations, the goal of the study is to examine the direct effects of gravity on the cavity collapse. In this paper we present ground-based research on these effects and outline a microgravity experiment destined for ESA Microgravity Research Campaign. The proposed experiment uses a focused laser to generate a highly spherical bubble in an extended water volum

2007

Water drops and cavitation bubbles in microgravity

Mohamed Farhat, Danail Obreschkow, Philippe Kobel

We realized an experimental setup to study the dynamics of cavitation bubbles inside spherical water drops produced in microgravity (8th Student Parabolic Flight Campaign, European Space Agency ESA). Water volumes of up to 8 ml (25 mm diameter) were expelled through a specially designed injector tube. The latter contained a porous hydrophilic foam and was particularly coated to ensure a stable and attached water drop. Single cavitation bubbles were then generated by an electrical discharge inside the drop.

2005

Contribution à l'étude de l'érosion de cavitation : mécanismes hydrodynamiques et prédiction

Mohamed Farhat

In the field of hydraulic power plant, the leading edge cavitation is often responsible of sever erosion which may cause a premature shutdown of energy production with costly consequences. This type of cavitation is characterized by an attached vapour cavity at the leading edge of the blades. Transient vapour vortices are generated and convected by the mean ow to the pressure recovery region where they collapse violently. The resulting water hammer pressure is responsible of material damage. In order to inv

EPFL1994

Cavitation erosion, impact intensity and pit size distribution of jet and vortex cavitation

François Avellan, Mohamed Farhat

Three different methods of cavitation erosion measurement are compared and correlated with weight loss rates in two cavitation set-ups: a high-pressure cavitation jet producing a high repetition rate of a wide range of impact intensities and a single vortex machine producing a low repetition rate of large collapses. The electrochemical cavitation activated current measurements on pure titanium sensors are calibrated on the jet and used to evaluate erosion rates on the vortex. The cavitation pit counting tec

ASME1993

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Related publications (11)

Advanced imaging and cavitation bubbles as promising tools for hemodynamic disorders diagnosis and treatment

EPFL2025

RANS computations of a confined cavitating tip-leakage vortex

Mohamed Farhat, Matthieu Dreyer

2018

Dynamics of the precessing vortex rope and its interaction with the system at Francis turbines part load operating conditions

François Avellan, Arthur Tristan Favrel, Christian Landry, Andres Müller, Keita Yamamoto, Joao Gomes Pereira Junior

2017

Unsteady hydraulic simulation of the cavitating part load vortex rope in Francis turbines

François Avellan, Arthur Tristan Favrel

2017

X-Ray Diffraction Observations of a Charge-Density-Wave Order in Superconducting Ortho-II YBa_{2}Cu_{3}O_{6.54} Single Crystals in Zero Magnetic Field

Amer Physical Soc2013