Publications by Philipp Kobel | EPFL Graph Search

Detailed experiments on weakly deformed cavitation bubbles

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

We present high-precision experiments conducted with the aim to better characterise weak deformations of single cavitation bubbles. Using two needle hydrophones and a high-speed photodetector, we record the timings of shock waves and luminescence emitted a ...

SPRINGER2019

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

Luminescence from cavitation bubbles deformed in uniform pressure gradients

Mohamed Farhat, Danail Obreschkow, Philipp Kobel, Outi Supponen

Presented here are observations that demonstrate how the deformation of millimetric cavitation bubbles by a uniform pressure gradient quenches single-collapse luminescence. Our innovative measurement system captures a broad luminescence spectrum (wavelengt ...

2017

Scaling laws for jets of single cavitation bubbles

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

Fast liquid jets, called micro-jets, are produced within cavitation bubbles experiencing an aspherical collapse. Here we review micro-jets of different origins, scales and appearances, and propose a unified framework to describe their dynamics by using an ...

Cambridge University Press2016

Radial Shock Wave Devices Generate Cavitation

Mohamed Farhat, Philipp Kobel

Background Conflicting reports in the literature have raised the question whether radial extracorporeal shock wave therapy (rESWT) devices and vibrating massage devices have similar energy signatures and, hence, cause similar bioeffects in treated tissues. ...

Public Library of Science2015

The inner world of a collapsing bubble

Mohamed Farhat, Danail Obreschkow, Philipp Kobel, Outi Supponen

Amer Inst Physics2015

Inferring the magnetic field vector in the quiet Sun III. Disk variation of the Stokes profiles and isotropism of the magnetic field

Philipp Kobel

Recent investigations of the magnetic field vector properties in the solar internetwork have provided diverging results. While some works found that the internetwork is mostly pervaded by horizontal magnetic fields, other works argued in favor of an isotro ...

EDP Sciences2013

The quest for the most spherical bubble: experimental setup and data overview

Mohamed Farhat, Danail Obreschkow, Nicolas Dorsaz, Philipp Kobel, Marc Tinguely, Aurèle De Bosset

We describe a recently realized experiment producing the most spherical cavitation bubbles today. The bubbles grow inside a liquid from a point plasma generated by a nanosecond laser pulse. Unlike in previous studies, the laser is focussed by a parabolic m ...

Springer Verlag2013

MicroFactory : Miniaturized Modular Cleanroom Concept for Automated Production

Philipp Kobel

Production in a controlled environment is becoming an increasingly important issue in various branches of industry. In the food, pharmaceutical, optical and semiconductor industries, today’s mass production would not be possible without so-called “cleanroo ...

EPFL2013

The continuum intensity as a function of magnetic field II. Local magnetic flux and convective flows

Philipp Kobel

Context. To deepen our understanding of the role of small-scale magnetic fields in active regions (ARs) and in the quiet Sun (QS) on the solar irradiance, it is fundamental to investigate the physical processes underlying their continuum brightness. Previo ...

2012

Energy partition at the collapse of spherical cavitation bubbles

Mohamed Farhat, Danail Obreschkow, Nicolas Dorsaz, Philipp Kobel, Marc Tinguely, Aurèle De Bosset

Spherically collapsing cavitation bubbles produce a shock wave followed by a rebound bubble. Here we present a systematic investigation of the energy partition between the rebound and the shock. Highly spherical cavitation bubbles are produced in micrograv ...

American Physical Society2012

Confined shocks inside isolated liquid volumes: A new path of erosion?

Mohamed Farhat, Danail Obreschkow, Nicolas Dorsaz, Philipp Kobel, Marc Tinguely, Aurèle De Bosset

The unique confinement of shock waves inside isolated liquid volumes amplifies the density of shock–liquid interactions. We investigate this universal principle through an interdisciplinary study of shock-induced cavitation inside liquid volumes, isolated ...

American Institute of Physics2011

Bubbles in drops: from cavitation to exploding stars

Mohamed Farhat, Danail Obreschkow, Nicolas Dorsaz, Philipp Kobel, Marc Tinguely, Aurèle De Bosset

APS2011

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

Mohamed Farhat, Danail Obreschkow, Nicolas Dorsaz, Philipp Kobel, Aurèle De Bosset

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

Cavitation Bubble Dynamics inside Liquid Drops in Microgravity

Claude Nicollier, Mohamed Farhat, Danail Obreschkow, Nicolas Dorsaz, Philipp Kobel, Aurèle De Bosset

We report a fundamental study of single cavitation bubbles inside quasi-spherical water drops produced in microgravity (42nd ESA parabolic flight campaign, 8th ESA student parabolic flight campaign). High-speed imaging revealed implications of isolated, fi ...

2006

Interaction of a cavitation bubble with a spherical free surface

Mohamed Farhat, Danail Obreschkow, Nicolas Dorsaz, Philipp Kobel, Aurèle De Bosset

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 ...

2006