Publications
Here is a full list of my publications in international peer-reviewed journals, with a short (and subjective) description in one sentence, and images illustrating the most representative articles.
[94] M. V. Paludan, B. Dollet, P. Marmottant, K. H. Jensen, Elastohydrodynamic interactions in soft hydraulic knots, J. Fluid Mech. 984, A55 (2024).
We study the hydraulic characteristics of soft intertwined channels, from a single hydraulic knot where two connected channels interact through a thin flexible membrane, to multiple knot configurations. We rationalise their nonlinear flow rate-pressure drop relations, and use them to rectify oscillatory flows.
[93] C. Hadji, B. Dollet, B. Coasne, E. Lorenceau, Soap-film membranes for CO2/air separation, Langmuir 40, 1237-1334 (2024).
In this follow-up of [79], we quantify the permability of soap films to gas mixtures of N2, O2 and CO2. While we recover previous values for the permeabilities for N2 and O2, we show that in the presence of surfactants, the permeability of CO2 is reduced and depends on its molar fraction.
[92] B. Dollet, Coarsening of foams driven by concentration gradients of gases of different solubilities, Langmuir 39, 16174-16181 (2023).
I study experimentally and theoretically the evolution of a bamboo foam made of an insoluble gas, and put initially into contact with a soluble gas. I show that the bubbles progressively swell, and that the dynamics can be rationalised by an effective diffusion model.
[91] A. Caumont, O. Stephan, E. Bossy, B. Dollet, C. Quilliet, P. Marmottant, Acoustic tokamak with strongly coupled toroidal bubbles, Phys. Rev. E 108, 045105 (2023).
We study the coupled resonances of an assembly of an acoustic Tokamak: toroidal bubbles disposed along a circle. We identify several modes, and we show that the fundamental resonance frequency of the Tokamak can be much lower than that of a single bubble.
[90] P. Trinh, A. Mikhailovskaya, G. Lefèvre, N. Pantoustier, P. Perrin, E. Lorenceau, B. Dollet, C. Monteux, Relation between oxidation kinetics and reactant transport in an aqueous foam, J. Colloid Interface Sci. 643, 267-275 (2023).
By monitoring the time evolution of the oxidation of a copper cylinder in an acid foam, we show that foams are exquisite media to enhance chemical reactions involving both gas and liquids as reactants, since gas is efficiently transported across the bubbles while liquid is efficiently transported through the network of liquid channels.
[89] F. Schott, B. Dollet, S. Santucci, C. Claudet, M. Argentina, C. Raufaste, R. Mokso, Three-dimensional liquid foam flow through a hopper resolved by fast X-ray microtomography, Soft Matter 19, 1300-1311 (2023). Cover page.
We study in three dimensions and in real time the flow of a flow through a hourglass-like geometry, featuring a convergent and a divergent channel; we show in particular a marked asymmetry of the bubble shape, passing from prolate to oblate between the convergent and the divergent part.
[88] J. Lamolinairie, B. Dollet, J. L. Bridot, P. Bauduin, O. Diat, L. Chiappisi, Probing foams from the nanometer to the millimeter scale by coupling small-angle neutron scattering, imaging, and electrical conductivity measurements, Soft Matter 18, 8733-8747 (2022). Cover page.
A new cell of foam characterisation is proposed, coupling small-angle neutron scattering, electrical conductivity measurements and optical imaging, and enabling a multiscale and real-time quantification of foam coarsening.
[87] M. Alloul, B. Dollet, O. Stephan, E. Bossy, C. Quilliet, P. Marmottant, Acoustic resonance frequencies of underwater toroidal bubbles, Phys. Rev. Lett. 129,134501 (2022).
We study bubbles enclosed in toroidal frames, and we show that their resonance frequency displays a logarithmic dependence on the ratio of the two radii of the torus.
[86] L. Keiser, P. Marmottant, B. Dollet, Intermittent air invasion in pervaporating compliant microchannels, J. Fluid Mech. 948, A52 (2022).
We show that the presence of a constriction drastically impairs the pervaporation-induced drying dynamics of a compliant microchannel, inducing stops and jumps arising from the coupling of pinning, capillary pressure and compliance; this is likely the origin of the intermittent drying dynamics observed in leaves.
[85] J. Pierre, V. Leroy, B. Dollet, A toy model for the effective density of acoustic metamaterials, Proc. R. Soc. A 478, 20210861 (2022).
We present a simple model based on two springs and two masses to clarify the frequency ranges of the negative mass regime, deduce from it the effective density of a model metamaterial, and compare our predictions to real acoustic metamaterials such as membrane-based systems or liquid foams.
[84] C. Pasquier, S. Pezennec, A. Bouchoux, B. Cabane, V. Lechevalier, C. Le Floch-Fouéré, G. Paboeuf, M. Pasco, B. Dollet, L. T. Lee, S. Beaufils, Protein transport upon advection at the air/water interface: When charge matters, Langmuir 37, 12278-12289 (2021).
This experimental study shows that in the formation of layers of proteins at the air/water interface, both a positive charge of the proteins and the presence of advection favour the formation of multilayers, while monolayers are formed in other conditions. However, classical diffusion/advection models do not capture the kinetics of multilayer formation.
[83] K. N. Chagua Encarnacion, P. Marmottant, B. Dollet, Pervaporation-induced drying in networks of channels of variable width, Microfluid. Nanofluid. 25, 71 (2021).
In this follow-up of [72] and [80], we elucidate the role of cross-section variations on the dynamics of drying by pervaporation of single channels and branched networks.
[82] G. Chabouh, B. Dollet, C. Quilliet, G. Coupier, Spherical oscillations of encapsulated microbubbles: Effect of shell compressibility and anisotropy, J. Acoust. Soc. Am. 149, 1240-1257 (2021).
In this theoretical study, we extend the models of ultrasound contrast agent coated microbubbles by accounting for two hitherto overlooked effects: the compressibility of the material constituting the shell, and its possible elastic anisotropy.
[81] M. Boughzala, O. Stephan, E. Bossy, B. Dollet, P. Marmottant, Polyhedral bubble vibrations, Phys. Rev. Lett. 126, 054502 (2021). Cover page.
We study bubbles enclosed in polyhedral frames. For the five Platonic solids (tetrahedron, cube, octahedron, dodecahedron, icosahedron), we show that the resonance frequency equals that of a sphere of equivalent radius within 10%, and we use fullerene cages to fix large bubbles against gravity.
[80] B. Dollet, K. N. Chagua Encarnacion, R. Gautier, P. Marmottant, Drying by pervaporation in elementary channel networks, J. Fluid Mech. 906, A6 (2021).
We quantify experimentally the dynamics of drying by in elementary networks (simple branches and loops) embedded in a permeable medium. This model biomimetic study is a step towards understanding the complex drying dynamics in leaves.
[79] C. Hadji, B. Dollet, H. Bodiguel, W. Drenckhan, B. Coasne, E. Lorenceau, Influence of fluorocarbon gaseous environment on the permeability of foam films to air, Langmuir 36, 13236-13243 (2020).
We quantify the permability of soap films to air in the presence of insoluble perfluorocarbon gases using a new yet simple experiment. The results suggest that the permeability continuously evolves in time as a result of the adsorption of perfluorocarbon molecules on the gas/liquid interfaces.
[78] F. Elias, J. Crassous, C. Derec, B. Dollet, W. Drenckhan, C. Gay, V. Leroy, C. Noûs, J. Pierre, A. Saint-Jalmes, The acoustics of liquid foams, Curr. Opin. Colloid Interface Sci. 50, 101391 (2020). Review article.
We review the acoustic properties of liquid foams, summarising the main experimental measurements, the current status of understanding and the pending issues, especially concerning the origin of sound dissipation in foams.
[77] M. Versluis, E. Stride, G. Lajoinie, B. Dollet, T. Segers, Ultrasound contrast agent modeling: A review, Ultrasound Med. Biol. 46, 2117-2144 (2020). Review article.
We review the theoretical model of ultrasound contrast agent microbubbles, starting from free gas bubbles and surveying the effet of shell mechanics, nonspherical and asymmetric oscillations, the effect of surrounding walls, microstreaming, shedding and acoustic radiation forces.
[76] B. Dollet, E. Lorenceau, F. Gallaire, Transition from exponentially damped to finite-time arrest liquid oscillations induced by contact angle hysteresis, Phys. Rev. Lett. 124, 104502 (2020).
We show experimentally that wetting conditions have dramatic consequences on the damping of liquid oscillations of a liquid column in a U-shaped tube, and identify contact angle hysteresis as a solid-like friction mechanism which deeply alter the damping dynamics.
[75] N. Taccoen, B. Dollet, C. N. Baroud, Order to disorder transition in a coarsening two-dimensional foam, Phys. Rev. Lett. 123, 238006 (2019).
We show experimentally that an initially almost perfectly ordered, crystalline two-dimensional foam coarsens in two successive steps: first, it loses crystallinity at still moderate bubble area changes; second, its polydispersity increases and tends towards the well documented self-similar regime of ageing.
[74] M. Kerdraon, J. D. McGraw, B. Dollet, M. C. Jullien, Self-similar relaxation of confined microfluidic droplets, Phys. Rev. Lett. 123, 024501 (2019).
We deform flat microdroplets confined along two dimensions to adopt a pancake-like shape, and study the subsequent shape relaxation. We show that it is self-similar in space and time, and interpret these results invoking dissipation in the gutters along the drop and menisci.
[73] E. Forel, B. Dollet, D. Langevin, E. Rio, Coalescence in two-dimensional foams: A purely statistical process dependent on film area, Phys. Rev. Lett. 122, 088002 (2019).
We propose an experimental study of foam coalescence in two dimensions, with finely controlled parameters like the radius of the liquid channels, and a large statistics of individual coalescence events. Our study suggests that the coalescence rate is simply proportional to the area of liquid films between bubbles.
[72] B. Dollet, J. F. Louf, M. Alonzo, K. H. Jensen, P. Marmottant, Drying of channels by evaporation through a permeable medium, J. R. Soc. Interface 16, 20180690 (2019).
We propose a biomimetic experiment of leaf drying by studying the dynamics of drying of initially water-filled single rectangular channels embedded in a permeable medium, and we provide an analytical prediction of this dynamics by solving the diffusion of water through the permebale medium.
[71] B. Dollet, P. Marmottant, V. Garbin, Bubble dynamics in soft and biological matter, Annu. Rev. Fluid Mech. 51, 331-355 (2019). Review article.
We survey the existing and recent research relating bubble acoustics and soft and biological matter. Starting with the basics of bubble dynamics, we review how bubbles behave in viscoelastic media, or when coated by a viscoelastic interface, or when confined by soft objects.
[70] A. A. Doinikov, B. Dollet, P. Marmottant, Cavitation in a liquid-filled cavity surrounded by an elastic medium: Intercoupling of cavitation events in neighboring cavities, Phys. Rev. E 98, 013108 (2018).
In this follow-up of [66], we compute the stress propagating in an elastic medium with a liquid cavity where a cavitation bubble appears, and we quantify the resulting pressure modification in a second cavity where cavitation might occur, as a first step to understand spatiotemporal correlations of cavitation events.
[69] J. F. Louf, N. Bertin, B. Dollet, O. Stephan, P. Marmottant, Hovering microswimmers exhibit ultrafast motion to navigate under acoustic forces, Adv. Mater. Interfaces 5, 1800425 (2018).
We fabricate and study acoustic microswimmers, and we discuss the competing effect of the acoustic radiation force and of the acoustic streaming on the propulsion of such swimmers.
[68] G. Lajoinie, Y. Luan, E. Gelderblom, B. Dollet, F. Mastik, H. Dewitte, I. Lentacker, N. de Jong, M. Versluis, Non-spherical oscillations drive the ultrasound-mediated release from tageretted microbubbles, Commun. Phys. 1, 22 (2018).
Combining high-speed fluorescence imaging and ultra-high speed imaging reveals that coating shedding from a coated microbubble targetted to a wall is strongly related to its nonspherical oscillations, and shed material tends to be transported by streaming away from the wall.
[67] F. Boulogne, B. Dollet, Convective evaporation of vertical films, Soft Matter 14, 1665-1671 (2018).
In this follow-up of [64], motivated by the influence of evaporation on the stability of soap films, we study experimentally and theoretically the evaporation rate from vertical slabs of hydrogels, and we show the importance of natural convection to explain this rate.
[66] A. A. Doinikov, B. Dollet, P. Marmottant, Model for the growth and finite-amplitude oscillations of a cavitation bubble in a spherical liquid-filled cavity enclosed in an elastic medium, Phys. Rev. E 97, 013108 (2018).
In the context of confined cavitation as happens in trees, we compute theoretically the nonlinear oscillations of a bubble in a cavity, accounting for the weak compressibility of the liquid.
[65] F. Viola, F. Gallaire, B. Dollet, Sloshing in a Hele-Shaw cell: experiments and theory, J. Fluid Mech. 831, R1 (2017).
Sloshing is studied in a narrow cell. When the solution viscosity is increased, the resonance peak of the fundamental mode disappears. Using Darcy-like approximation yields a self-consistent treatment of sloshing modes and viscous damping, and predictions agree with our data.
[64] B. Dollet, F. Boulogne, Natural convection above circular disks of evaporating liquids, Phys. Rev. Fluids 2, 053501 (2017).
We study experimentally and theoretically the transition between diffusion-driven and convection-driven evaporation of flat surfaces of liquids, with scaling laws depending on the Grashof number, which compares natural convection to diffusive processes.
[63] B. Géraud, Y. Méheust, I. Cantat, B. Dollet, Lamella division in a foam flowing through a two-dimensional porous medium: A model fragmentation process, Phys. Rev. Lett. 118, 098003 (2017).
The bubble size distribution of a foam flowing through a porous medium evolves through the division of lamellae when impinging on an obstacle. We characterise all such individual fragmentation events, and model them with a mean-field fragmentation equation, predicting the evolution of the size distribution.
[62] B. Dollet, D. Lohse, Pinning stabilizes neighboring surface nanobubbles against Ostwald ripening, Langmuir 32, 11335-11339 (2016).
We show theoretically that a pair of pinned surface (nano)bubbles of arbitrary size, interacting through the diffusion of dissolved gas, remain in stable equilibrium, in contrast with the classical Ostwald ripening.
[61] M. Monloubou, M. A. Bruning, A. Saint-Jalmes, B. Dollet, I. Cantat, Blast wave attenuation in liquid foams: role of gas and evidence of an optimal bubble size, Soft Matter 12, 8015-8024 (2016).
We reveal the existence of an optimal bubble size to maximise blast wave attenuation by liquid foams, and its dependence on the gas, in qualitative agreement with the thermal model proposed in [55].
[60] F. Viola, P. T. Brun, B. Dollet, F. Gallaire, Foam on troubled water: capillary induced finite-time arrest of sloshing waves, Phys. Fluids 28, 091701 (2016).
Contrary to the canonical exponential viscous damping, a layer of foam on top of a glass of water damps sloshing in finite time, owing to the sublinear dependence of the wall friction of menisci on their slip velocity.
[59] J. Crassous, P. Chasle, J. Pierre, A. Saint-Jalmes, B. Dollet, Synchronized diffusive wave spectroscopy: Principle and application to sound propagation in aqueous foams, Phys. Rev. E 93, 032611 (2016).
By synchronising a harmonic acoustic forcing on a foam and the detection of the resulting displacement field using diffusive wave spectroscopy, we measure the amplitude of phase of the acoustic wave propagating through the foam, hence its acoustic properties.
[58] B. Géraud, S. A. Jones, I. Cantat, B. Dollet, Y. Méheust, The flow of a foam in a two-dimensional porous medium, Water Resour. Res. 52, 773-790 (2016).
We reveal by experimental visualisation the rich phenomenology of a foam flowing in a disordered porous medium: preferential paths, a strong spatio-temporal intermittency, and a coupling between bubble area and velocity.
[57] J. Seiwert, J. Pierre, B. Dollet, Coupled vibrations of a meniscus and liquid films, J. Fluid Mech. 788, 183-208 (2016).
We study the acoustically forced vibration of the "diaboloid", a horizontal film attached to two catenary films by a circular meniscus, as a macroscopic model system of a foam subjected to pressure waves.
[56] B. Dollet, C. Bocher, Flow of foam through a convergent channel, Eur. Phys. J. E 38, 123 (2015).
The elastic stress, plasticity, and velocity field of a foam flowing in a convergent channel are quantified, showing the influence of the surface viscoelasticity of the solution and the local dependence of the yield stress on the loading rate.
[55] M. Monloubou, A. Saint-Jalmes, B. Dollet, I. Cantat, Influence of bubble size and thermal dissipation on compressive wave attenuation in liquid foams, EPL 112, 34001 (2015).
We show that blast wave attenuation by liquid foams depends on bubble size, which we model by thermal gradients within the bubbles in contact with the liquid phase approximated as a thermostat.
[54] C. Raufaste, B. Dollet, K. Mader, S. Santucci, R. Mokso, Three-dimensional foam flow resolved by fast X-ray tomographic microscopy, EPL 111, 38004 (2015).This is the first time-resolved observation of a foam flowing in three dimensions at the bubble scale, using recent advances in fast X-ray tomography.
[53] A. Scagliarini, B. Dollet, M. Sbragaglia, Non-locality and viscous drag effects on the shear localisation in soft glassy materials, Colloids Surf. A 437, 133-140 (2015).
We present a model coupling nonlocal rheology of complex fluids and the friction of a confining wall, and show how shear localisation comes from the combination of both effects.
[52] J. Pierre, B. Giraudet, P. Chasle, B. Dollet, A. Saint-Jalmes, Sound propagation in liquid foams: Unraveling the balance between physical and chemical parameters, Phys. Rev. E 91, 042311 (2015).
We show experimentally that the acoustic properties of foams are qualitatively independent of physicochemical parameters, supporting further our physical model of [48].
[51] B. Dollet, A. Scagliarini, M. Sbragaglia, Two-dimensional plastic flow of foams and emulsions in a channel: experiments and lattice Boltzmann simulations, J. Fluid Mech. 766, 556-589 (2015).
In this joint experimental and numerical study, the Poiseuille flow of a foam or an emulsion in a straight channel is quantified; the residual plastic activity at the centre of the channel agrees with nonlocal rheology models.
[50] B. Dollet, C. Raufaste, Rheology of liquid foams, C. R. Physique 15, 731-747 (2014). Review article.
We review the existing research on the rheology of foams and emulsions, with a special emphasis on modern questions such as shear localisation and nonlocal rheology.
[49] B. Dollet, S. A. Jones, Y. Méheust, I. Cantat, Influence of the elastic deformation of a foam on its mobility in a channels of linearly varying width, Phys. Rev. E 90, 023006 (2014).
When flowing in a convergent and a divergent channel in parallel, confined foams flow preferentially in the convergent channel, because of a coupling between kinematics, elastic deformation and foam-wall friction.
[48] J. Pierre, B. Dollet, V. Leroy, Resonant acoustic propagation and negative density in liquid foams, Phys. Rev. Lett. 112, 148307 (2014). La Recherche 2015 Award for the best article in Physics of a French team.
This study reconciles measurements of foam acoustics in a unified, fully predictive model, and reveals that foams are natural disordered acoustic metamaterials.
[47] J. Seiwert, B. Dollet, I. Cantat, Pulling soap films out of a bath: role of interfacial viscoelasticity, J. Fluid Mech. 739, 124-142 (2014).
The thickness of a soap film withdrawn from a bath is predicted as a function of the capillary number and the surface viscoelasticity, showing the crucial role of surface elasticity, and that surface viscosity alone is incompatible with a steady solution.
[46] I. Ben Salem, I. Cantat, B. Dollet, Response of a two-dimensional liquid foam to air injection: Influence of surfactants, critical velocities and branched fracture, Colloids Surf. A 438, 41-46 (2013).
In this follow-up of [41], we study the ductile and brittle fracture of liquid foams, and in particular how surface viscoelasticity tends to promote brittle fracture.
[45] L. Stricker, B. Dollet, D. Fernández Rivas, D. Lohse, Interacting bubble clouds and their sonochemical production, J. Acoust. Soc. Am. 134, 1854-1862 (2013).
An acoustically driven air pocket trapped in a pit etched on a surface can emit a bubble cluster. When several pits are present, the resulting bubble clusters interact in a nontrivial way, mediated by secondary Bjerknes forces.
[44] J. Seiwert, M. Monloubou, B. Dollet, I. Cantat, Extension of a suspended soap film: a homogeneous dilatation followed by new film extraction, Phys. Rev. Lett. 111, 094501 (2013).
An extended freely suspended film does not stretch uniformly, but its expansion proceeds mostly by the withdrawal of new film from the meniscus, with a thickness set by the meniscus speed.
[43] S. A. Jones, B. Dollet, Y. Méheust, S. J. Cox, I. Cantat, Structure-dependent mobility of an aqueous foam flowing along two parallel channels, Phys. Fluids 25, 063101 (2013).
The flux distribution of a foam in two parallel straight channels is dictated by wall friction, which leads to strong variations of the flux ratio when the foam is confined as a bamboo or a staircase structure.
[42] M. Erpelding, B. Dollet, A. Faisant, J. Crassous, A. Amon, Diffusing wave spectroscopy contribution to strain analysis, Strain 49, 167-174 (2013).
We present a new full-field strain measurement method based on diffusing-wave spectroscopy, with an extreme sensitivity as major advantage.
[41] I. Ben Salem, I. Cantat, B. Dollet, Response of a two-dimensional liquid foam to air injection: swelling rate, fingering and fracture, J. Fluid Mech. 714, 258-282 (2013).
We show that a foam subjected to localised air injection displays ductile and brittle fracture by the growth of an inner crack, whose growth rate and fingering is experimentally and theoretically quantified.
[40] I. Ben Salem, R. M. Guillermic, C. Sample, V. Leroy, A. Saint-Jalmes, B. Dollet, Propagation of ultrasound in aqueous foams: bubble size dependence and resonance effects, Soft Matter 9, 1194-1202 (2013).
We reveal that foam shows an acoustic resonance, with a given bubble size for which acoustic transmission displays a minimum.
[39] K. Mader, R. Mokso, C. Raufaste, B. Dollet, S. Santucci, J. Lambert, M. Stampanoni, Quantitative 3D characterization of cellular materials: segmentation and morphology of foam, Colloids Surf. A 415, 230-238 (2012).
We present new methods to analyse images of three-dimensional cellular materials, and apply them to three-dimensional images of liquid foams acquired by fast X-ray tomography.
[38] I. Cantat, B. Dollet, Liquid films with high surface modulus moving in tubes: dynamic wetting film and jumpy motion, Soft Matter 8, 7790-7796 (2012).
Film lamellae pushed in tubes with wetted walls present a surprising dynamics when surface viscoelasticity is large: they push the wetting films centimetres ahead, and exhibit stick-slip motion.
[37] J. Delacotte, L. Montel, F. Restagno, B. Scheid, B. Dollet, H. A. Stone, D. Langevin, E. Rio, Plate coating: Influence of concentrated surfactants on the film thickness, Langmuir 28, 3821-3830 (2012).
We measure the thickness of a coating film withdrawn from a bath, for various soap solutions, and show that the thickness is larger than the Landau-Levich prediction below a capillary number depending on concentration and on the ionic nature of the solution.
[36] W. van Hoeve, B. Dollet, M. Versluis, D. Lohse, Microbubble formation and pinch-off scaling exponent in flow-focusing devices, Phys. Fluids 23, 092001 (2011).
We investigate the gas jet break-up and the resulting microbubble formation in a microfluidic flow-focusing device using ultra high-speed imaging, clarifying the mechanisms at stake just before break-up.
[35] V. Garbin, M. Overvelde, B. Dollet, N. de Jong, D. Lohse, M. Versluis, Unbinding of targeted ultrasound contrast agent microbubbles by secondary acoustic forces, Phys. Med. Biol. 56, 6161-6177 (2011).
We study the coupled dynamics of two ultrasound contrast agent microbubbles bond to the wall, and show that they can unbind when their interaction by secondary Bjerknes forces exceed the binding strength.
[34] M. Overvelde, V. Garbin, B. Dollet, N. de Jong, D. Lohse, M. Versluis, Dynamics of coated microbubbles adherent to a wall, Ultrasound Med. Biol. 37, 1500-1508 (2011).
We show experimentally that adhesion forces on a targetted ultrasound contrast agent microbubble drastically affect its resonance properties.
[33] W. van Hoeve, B. Dollet, J. M. Gordillo, M. Versluis, L. van Wijngaarden, D. Lohse, Bubble size prediction in co-flowing streams, EPL 94, 64001 (2011).
We provide a theoretical prediction of bubble size formed in the jetting regime in a parallel co-flow configuration, using a linear stability analysis.
[32] H. J. Vos, B. Dollet, M. Versluis, N. de Jong, Nonspherical shape oscillations of coated microbubbles in contact with a wall, Ultrasound Med. Biol. 37, 935-948 (2011).
We quantify the coupled volumetric oscillations, translation, and nonspherical oscillations of ultrasound contrast agent microbubbles in non-adhesive contact with a wall, and the wall stress resulting from this dynamics.
[31] S. A. Jones, B. Dollet, N. Slosse, Y. Jiang, S. J. Cox, F. Graner, Two-dimensional constriction flows of foams, Colloids Surf. A 382, 18-23 (2011).
We compare constriction flows of foams from various experimental and numerical studies, using in particular the data from [24].
[30] J. Sijl, M. Overvelde, B. Dollet, V. Garbin, D. Lohse, M. Versluis, N. de Jong, “Compression-only” behavior: A second order nonlinear response of ultrasound contrast agent microbubbles, J. Acoust. Soc. Am. 129, 1729-1739 (2011).
We provide a detailed study of "compression-only", a nonlinear oscillation phenomenon of coated bubbles, whereby their expansion amplitude is smaller that their compression amplitude when both are compared to the equilibrium radius.
[29] I. Cheddadi, P. Saramito, B. Dollet, C. Raufaste, F. Graner, Understanding and predicting viscous, elastic, plastic flow, Eur. Phys. J. E 34, 1 (2011).
We show that a viscoelastoplastic continuum model reproduces quantitatively all the non-trivial features of the flow of a foam around an obstacle.
[28] M. Overvelde, V. Garbin, J. Sijl, B. Dollet, N. de Jong, D. Lohse, M. Versluis, Nonlinear shell behavior of phospholipid-coated microbubbles, Ultrasound Med. Biol. 36, 2080-2092 (2010).
The viscoelastic shell of ultrasound contrast agent microbubbles exacerbes their nonlinear oscillation properties, and causes a strong decrease of their resonance frequency at increasing amplitude.
[27] J. Sijl, B. Dollet, M. Overvelde, V. Garbin, T. Rozendal, N. de Jong, D. Lohse, M. Versluis, Subharmonic behavior of phospholipid-coated ultrasound contrast agent microbubbles, J. Acoust. Soc. Am. 128, 3239-3252 (2010).
We quantify the subharmonic volumetric oscillations of ultrasound contrast agent microbubbles and show that they appear at very low forcing acoustic amplitude, owing to the shell nonlinear behaviour.
[26] M. Versluis, D. E. Goertz, P. Palanchon, I. L. Heitman, S. M. van der Meer, B. Dollet, N. de Jong, D. Lohse, Microbubble shape oscillations excited through ultrasonic parametric driving, Phys. Rev. E 82, 026321 (2010).
The acoustically forced nonspherical oscillations of uncoated bubbles are studied: their threshold is measured, and the mode selection mechanism is related to a parametric instability.
[25] M. Erpelding, R. M. Guillermic, B. Dollet, A. Saint-Jalmes, J. Crassous, Investigating acoustic-induced deformations in a foam using multiple light scattering, Phys. Rev. E 82, 021409 (2010).
The acoustically induced displacement of a foam in a cuvette is quantified by diffusive wave spectroscopy, thanks to the shear deformation localised in a viscoelastic boundary layer.
[24] B. Dollet, Local description of the two-dimensional flow of foam through a contraction, J. Rheol. 54, 741-760 (2010).
I quantify the flow of a foam through a constriction, measuring its elastic, plastic and viscous response. In particular, streamlines refocus far enough downstream the constriction, which is reminiscent of die swell.
[23] B. Dollet, I. Cantat, Deformation of soap films pushed through tubes at high velocity, J. Fluid Mech. 652, 529-539 (2010).
When pushed at high velocity in a tube with wetted walls, a film lamella first curves downstream and can even break, according to a simple criterion based on Bretherton-like friction force.
[22] B. Scheid, J. Delacotte, B. Dollet, E. Rio, F. Restagno, E. A. van Nierop, I. Cantat, D. Langevin, H. A. Stone, The role of surface rheology in liquid film formation, EPL 90, 24002 (2010).
We compute the influence of surface viscosity on the thickness of films withdrawn from a bath, and show that it is responsible of the slightly thicker films, compared to Landau-Levich prediction, obtained with a concentrated solution of an anionic surfactant
[21] J. Emile, A. Salonen, B. Dollet, A. Saint-Jalmes, A systematic and quantitative study of the link between foam slipping and interfacial viscoelasticity, Langmuir 25, 13412-13418 (2009).
We show that the pressure drop of a train of films in a tube, and shows that it deviates from the Bertherton law holding for free-shear boundary conditions at surprisingly low surface viscoelasticity.
[20] B. M. Borkent, H. Schönherr, G. Le Caër, B. Dollet, D. Lohse, Preferred sizes and ordering in surface nanobubble populations, Phys. Rev. E 80, 036315 (2009).
We study the size and spacing distribution of assemblies of surface nanobubbles, and show that they are further apart than a random assembly, which is a signature of their mutual repulsion owing to their competition to absorb dissolved gas.
[19] V. Garbin, B. Dollet, M. Overvelde, D. Cojoc, E. di Fabrizio, L. van Wijngaarden, A. Prosperetti, N. de Jong, D. Lohse, M. Versluis, History force on coated microbubbles propelled by ultrasound, Phys. Fluids 21, 092003 (2009).
Thanks to an optical trap, we study the acoustic coupling of two neighbouring ultrasound contrast agent microbubbles, showing that their translation can be captured only if viscous history force and no-slip boundary condition are accounted for.
[18] C. Raufaste, A. Foulon, B. Dollet, Dissipation in quasi-two-dimensional flowing foams, Phys. Fluids 21, 053102 (2009).
We quantify the dissipation of flowing foams confined by smooth plates for an extended range of liquid fraction, and deduce from our data an empirical relationship between the pressure drop, the velocity and the physical parameters of the foam.
[17] W. Drenckhan, B. Dollet, S. Hutzler, F. Elias, Soap films under large-amplitude oscillations, Phil. Mag. Lett. 88, 669-677 (2008).
We visualise the oscillations of soap films excited by a loudspeaker, showing a phenomenon of nonlinear self-adaptation whereby the liquid within the film gathers towards the centre of the oscillating films to form a drop.
[16] B. Dollet, S. M. van der Meer, V. Garbin, N. de Jong, D. Lohse, M. Versluis, Nonspherical oscillations of ultrasound contrast agent microbubbles, Ultrasound Med. Biol. 34, 1465-1473 (2008).
We propose the first systematic study of nonspherical oscillations of ultrasound contrast agent microbubbles, quantifying the onset of such shape oscillations and showing that the mode number is not clearly correlated to the bubble size (contrary to uncoated bubbles [26]).
[15] F. Graner, B. Dollet, C. Raufaste, P. Marmottant, Discrete rearranging disordered patterns, part I : Robust statistical tools in two or three dimensions, Eur. Phys. J. E 25, 349-369 (2008).
We propose a set of scalar, vectorial and tensorial descriptors of the elastic, plastic and viscous mechanical state of cellular materials.
[14] H. J. Vos, B. Dollet, J. G. Bosch, M. Versluis, N. de Jong, Non-spherical vibrations of microbubbles in contact with a wall – a pilot study at low mechanical index, Ultrasound Med. Biol. 34, 685-688 (2008).
We visualise simultaneously in top view and in side view the nonspherical oscillations of an ultrasouns contrast agent microbubble in contact with a wall, and show that oscillations may appear spherical in top view while they are nonspherical in side view.
[13] B. Dollet, W. van Hoeve, J. P. Raven, P. Marmottant, M. Versluis, Role of the channel geometry on the bubble pinch-off in flow-focusing devices, Phys. Rev. Lett. 100, 034504 (2008).
We reveal that bubble pinch-off in microfluidic flow-focusing devices is stable as long as the bubble neck remains confined by walls, and unstable and fast when the neck gets unconfined, which explains the high monodispersity of the resulting bubbles.
[12] B. Dollet, F. Graner, Two-dimensional flow of foam around circular obstacles: local measurements of elasticity, plasticity and flow, J. Fluid Mech. 585, 181-211 (2007).
We present a novel image analysis methodology to analyse the elastic, plastic and viscous flow of a foam, and apply it to the flow around a circular obstacle for various control parameters, revealing strong fore-aft asymmetries and a negative wake.
[11] C. Raufaste, B. Dollet, S. J. Cox, Y. Jiang, F. Graner, Yield drag in a two-dimensional foam flow around a circular obstacle: the role of fluid fraction, Eur. Phys. J. E 23, 217-228(2007).
Combining experiments and simulations, we quantify the dependence of the velocity-independent drag contribution of a foam flowing around a circular obstacle.
[10] S. M. van der Meer, B. Dollet, M. M. Voormolen, C. T. Chin, A. Bouakaz, N. de Jong, M. Versluis, D. Lohse, Microbubble spectroscopy of ultrasound contrast agents, J. Acoust. Soc. Am. 121, 648-656 (2007).
Using ultra-high speed imaging at 15 million frames per second, we measure the resonance curves of ultrasound contrast agent microbubbles of various radii, and quantify the shell viscoelastic parameters.
[9] B. Dollet, M. Durth, F. Graner, Flow of foam past an elliptical obstacle, Phys. Rev. E 73, 061404 (2006).
We quantify the dependence of the drag, lift and torque experiences by an ellipse in a flowing foam as a function of the orientation of the ellipse.
[8] S. J. Cox, B. Dollet, F. Graner, Foam flow around an obstacle: simulations of obstacle-wall interaction, Rheol. Acta 45, 403-410 (2006).
Using some of the tools that I developed to analyse foam flows [12], simulations of foam flows around off-centred circular obstacles in a channel are studied.
[7] C. L. Lin, I. Wang, B. Dollet, P. L. Baldeck, Velocimetry microsensors driven by linearly polarized optical tweezers, Optics Lett. 31, 329-331 (2006).
The dynamics of microscopic flag-shaped objects trapped in an optical tweezer and placed in a flow is analysed by a balance of the optical and hydrodynamic torques.
[6] B. Dollet, M. Aubouy, F. Graner, Anti-inertial lift in foams: a signature of the elasticity of complex fluids, Phys. Rev. Lett. 95, 168303 (2005).
We show that asymmetric obstacles in a foam flow experience a lift in the opposite direction compared to the aerodynamic lift, relate quantitatively this result to the elastic properties of the foam, and argue that it is a general property of elastic fluids.
[5] C. Quilliet, M. A. P. Idiart, B. Dollet, L. Berthier, A. Yekini, Bubbles in sheared two-dimensional foams, Colloids Surf. A 263, 95-100 (2005).
Using some of the tools that I developed to analyse foam flows [12], the segregation of big bubbles in an otherwise monodisperse foam under shear is studied.
[4] B. Dollet, F. Elias, C. Quilliet, A. Huillier, M. Aubouy, F. Graner, Two-dimensional flows of foams: drag exerted on circular obstacles and dissipation, Colloids Surf. A 263, 101-110 (2005).
This paper complement [3] by quantifying experimentally the influence of liquid fraction on the drag experienced by a circular obstacle in a foam flow, and the pressure drop of foam flows confined by a top wall.
[3] B. Dollet, F. Elias, C. Quilliet, C. Raufaste, M. Aubouy, F. Graner, Two-dimensional flow of foam around obstacles: force measurements, Phys. Rev. E 71, 031403 (2005).The drag experienced by obstacles in a foam flow is systematic studied, as function of control parameters as the velocity, bubble size, bulk viscosity, size and shape of the obstacle.
[2] S. Courty, B. Dollet, F. Elias, P. Heinig, F. Graner, Two-dimensional shear modulus of a Langmuir foam, Europhys. Lett. 64, 709-715 (2003). Erratum: B. Dollet, F. Elias, F. Graner, Two-dimensional shear modulus of a Langmuir foam, EPL 88, 69901 (2009).
A Langmuir foam is sheared by an optical fiber of micrometric size and simultaneously imaged by Brewster angle microscopy, showing a linear relationship between the elastic stress and the deformation of the Langmuir foam.
[1] S. Courty, B. Dollet, K. Kassner, A. Renault, F. Graner, Elasticity and plasticity of two-dimensional amorphous solid layers of beta-lactoglobulin, Eur. Phys. J. E 11, 53-59 (2003).
We investigate the mechanical properties of a two-dimensional amorphous solid constituted by a protein monolayer at the water surface forced by a glass fiber.