Capillary wave turbulence experiments in microgravity

Abstract

Using the FLUIDICS (Fluid Dynamics in Space) experiment in the International Space Station, turbulence of capillary waves at the air-water interface is experimentally investigated in weightlessness. Capillary waves are excited in a spherical container partially filled with water and undergoing sinusoidal or random oscillations. The fluctuations of the interface, recorded with two capacitive probes are analyzed by means of the frequency power spectrum of wave elevation. For high enough forcing amplitudes, we report power-law spectra with exponents close to the prediction of weak wave turbulence theory. However, in this experiment the free-surface steepness is not small compared to 1 and thus the investigated regimes correspond to strongly nonlinear wave turbulence.

Experiments in Surface Gravity–Capillary Wave Turbulence

“…Pure capillary wave turbulence has been reached experimentally either in low-gravity environment [in parabolic flight experiments (Falcón et al 2009) or onboard the International Space Station (Berhanu et al 2019)], or at the interface of two immiscible fluids of close densities, either in presence of an additional interface with air (Issenmann et al 2016) or without such interface (Düring & Falcón 2009). It leads to an excellent agreement with the ω −17/6 spectrum on more than two decades within the inertial range for weak enough forcing (Falcón et al 2009, Issenmann et al 2016) (see Figure 4d).…”

Succession of Resonances to Achieve Internal Wave Turbulence

“…[8], and references therein), wave turbulence for internal waves is a relatively unexplored phenomenon. Wave turbulence describes physical systems with a large number of dispersive and nonlinear interacting waves [9] and has been applied to gravity [10], capillary [11] and inertial waves [12,13], as well as waves in magnetized fluids [14] and in elastic plates [15]. New applications have recently emerged in condensed matter (superfluid helium and Bose-Einstein condensates), in nonlinear optics [16], and, most recently, in the study of gravitational waves in the early Universe [17].…”

Space-time resolved measurements of the effect of pinned contact line on the dispersion relation of water waves

“…In Figs. 6a − d, for one fixed frequency, we present the real part of the functions A n (x), with n = [1,2,3,4] and the fitted curves. We observe a very good agreement of the linear approximation and a decreasing amplitude as a function of n. In Fig.…”

“…7b) and n = 3. The small contribution of higher modes (n = [2,3]) indicates a more stretched surface produced by the tension between the pinned contact line against the wave induced perturbation. In this case, the transverse profile of the surface perturbation is higher in the center of the channel, due to the proximity of the lateral walls.…”

“…In the dynamics of surface waves, capillary effects become important when the geometry of the container is in the same order of magnitude as the capillary length or in low gravity conditions, where the main restoring force is the surface tension [1][2][3]. Several recent applications and experimental works make that the problem of calculating the damping and eigenfrequencies of gravity-capillary waves is still an active subject [4][5][6][7].…”