Flows induced by radiation pressure

Light, sound or waves can exert forces on the media through which they propagate. Since 2002 I have been studying the deformations of liquid interfaces, the flow of fluids as well as the motion of objects induced by light and sound in order to elucidate the wide variety of morphologies observed, to explain the similarities between the effects of these waves which are of such different natures and to exploit these phenomena to characterize liquids and interfaces. I present below the significant results since 2012.

Radiation couple exerted by the vortex beams – Vortex beams are characterized by a singularity of their phase. As a result, they carry not only momentum but also angular momentum. In collaboration with Andreas Anhaueser, Benjamin Sanchez-Padilla (PhD student) and Etienne Brasselet (LOMA, Université de Bordeaux), we have quantitatively studied how the transfer of angular momentum between a beam and matter induces a torque on the irradiated material which results in rotation of liquids or objects.

A. Anhaueser, R. Wunenburger E. Brasselet, Acoustic rotational manipulation using orbital angular momentum transfer, Physical Review Letters 109, 034301 (2012).
R. Wunenburger, JI Vazquez Lozano, E. Brasselet, Acoustic orbital angular momentum transfer to matter by chiral scattering, New Journal of Physics 17, 103022 (2015).
B. Sanchez-Padilla, L. Jonusauskas, M. Malinauskas, R. Wunenburger, E. Brasselet, Direct mechanical detection and measurement of wave-matter orbital angular momentum transfer by nondissipative vortex mode conversion, Physical Review Letters 123, 244301 (2019) .

Universality of interface deformations induced by electromagnetic and acoustic radiation pressure – In collaboration with Hugo Chesneau (PhD student), Nicolas Bertin (PhD student), Hamza Chraïbi, Jean-Pierre Delville and Etienne Brasselet (LOMA, Université de Bordeaux), we studied experimentally and numerically the deformations of liquid-liquid interfaces induced by electromagnetic and acoustic radiation pressure. By simultaneously numerically simulating the deformation of a liquid interface by a beam and the propagation of this beam through the deformed interface, we were able to explain the morphologies observed and the universality of the deformations obtained with these waves of such different natures.

N. Bertin, H. Chraïbi, R. Wunenburger, JP Delville, E. Brasselet, Universal morphologies of fluid interfaces deformed by the radiation pressure of acoustic or electromagnetic waves, Physical Review Letters 109, 244304 (2012).
H. Chesneau, H. Chraibi, N. Bertin, J. Petit, JP Delville, E. Brasselet and R. Wunenburger, Numerical simulation of universal morphogenesis of fluid interface deformations driven by radiation pressure, Physical Review E 106, 065104 (2022).

Characterization of liquid films by unsteady optical or acoustic radiation pressure – By transiently irradiating a liquid surface with a focused laser or ultrasonic beam, a momentary deformation is induced on it, the relaxation of which depends on the properties of the liquid. In collaboration with Bruno Issenmann (PhD student), Hamza Chraïbi and Jean-Pierre Delville (LOMA, Université de Bordeaux), we have developed an acoustic technique allowing the surface tension and viscosity of simple liquids to be determined without contact. Thanks to our collaboration with Gopal Verma (LOMA, Université de Bordeaux), we have extended this technique to thin films of viscous and viscoelastic liquids.

B. Issenmann, R. Wunenburger, H. Chraïbi, M. Gandil, JP Delville, Unsteady deformations of a free liquid surface caused by radiation pressure, Journal of Fluid Mechanics 682, 460 (2011).
G. Verma, H. Chesneau, H. Chraïbi, U. Delabre, R. Wunenburger, JP Delville, Contactless thin-film rheology unveiled by laser-induced nanoscale interface dynamics, Soft Matter (2020).