Publications de Danail Obreschkow

Vapor compression and energy dissipation in a collapsing laser-induced bubble

Mohamed Farhat, Danail Obreschkow, Armand Baptiste Sieber, Davide Bernardo Preso

The composition of the gaseous phase of cavitation bubbles and its role on the collapse remains to date poorly understood. In this work, experiments of single cavitation bubbles in aqueous ammonia serve as a novel approach to investigate the effect of the ...

Aip Publishing2024

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

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

Rebounds of deformed cavitation bubbles

Mohamed Farhat, Danail Obreschkow, Outi Supponen

Presented here are experiments clarifying how the deformation of cavitation bubbles affects their rebound. Rebound bubbles carry the remaining energy of a bubble following its initial collapse, which dissipates energy mainly through shock waves, jets, and ...

AMER PHYSICAL SOC2018

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

The inner world of a collapsing bubble

Mohamed Farhat, Danail Obreschkow, Philipp Kobel, Outi Supponen

Amer Inst Physics2015

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

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

Analytical approximations for the collapse of an empty spherical bubble

Mohamed Farhat, Danail Obreschkow

The Rayleigh equation 3/2 (R) over dot + R(R) double over dot + p rho(-1) = 0 with initial conditions R(0) = R-0, (R) over dot(0) = 0 models the collapse of an empty spherical bubble of radius R(T) in an ideal, infinite liquid with far-field pressure p and ...

2012

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

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

Nonorthogonal theory of polarons and application to pyramidal quantum dots

Marc-André Dupertuis, Elyahou Kapon, Sascha Dalessi, Danail Obreschkow

We present a general theory for semiconductor polarons in the framework of the Frohlich interaction between electrons and phonons. The latter is investigated using noncommuting phonon creation/annihilation operators associated with a natural set of nonorth ...

2007

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

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