Laboratoire Matière et Systèmes Complexes

There will be a live diffusion with Zoom.

Monday October 18th, 11h30

Contact Michael Berhanu to attend the visio-seminar

Manipulation of water waves in space and time using electrostriction

Benjamin Apffel, Institut Langevin, ESPCI Paris

Water waves are probably the easiest type of waves that one can observe in everyday life. However, their control is quite difficult and usually requires to place heavily invasive solid inclusions in water. In this seminar, I will present how electric fields can be used to control their propagation properties in a non-invasive and reconfigurable manner. In particular, I will describe how to implement classical refraction-based devices such as lenses, beam-splitters or guiding fibers. In a second part, I will show that one can also vary the propagation properties of water waves in a short time compared to the wave period using variable electric fields. Using this unusual regime of time varying medium we demonstrate experimentally the possibility to perform large frequency shifts on a wave packet. The case of sinusoidal modulation is also investigated. It offers the possibility to revisit Faraday instability that is used to propel floating bodies with parametrically excited water waves.

Figure : (Top) Water waves guided under an electrode using electrostriction and (Bottom) motor driven by parametrically excited water waves using variable electric field.