Characterization of capillary waves: A review and a new optical method

Abstract

The methods to study capillary waves have been reviewed, together with the emerging practical applications of theirs and new theoretical developments in the field. The focus is on monochromatic ripples of frequency in the range 0.1-10 kHz. A capillary wave apparatus has been constructed that combines several recent advances on the technique. It is based on profilometry of waves decaying with distance, with a highspeed video camera detecting light refracted by the surface. A code to process the images has been developed that executes a regression analysis to determine the characteristics of the wave. High precision and accuracy have been achieved: standard deviation from the mean of ±0.5% for the wavelength and ±7% for the decay length; mean deviations from the theoretical values ±0.2% for the wavelength and ±5% for the decay length. An analytic approximation for the dispersion relation has been used to determine the Gibbs elasticity of a surfactant monolayer from the data for decay length vs. frequency. The elasticity of an octanol monolayer has been determined with precision of ±1 mN/m, in excellent agreement with the theoretical value. Surface tension can be measured from the wavelength data with precision of ±0.3 mN/m. It has been demonstrated that the effect of the surface elasticity on the wavelength is significant and accurate wavelength data can actually be used to determine the elasticity if the surface tension is known.

A machine learning model for reconstructing skin-friction drag over ocean surface waves

“…Under these experimental conditions, the wavelength of wind-generated surface waves varies approximately from 15 to 50 cm, which is at larger scales than capillary waves with a wavelength in the sub-centimetre range (e.g. Slavchov, Peychev & Ismail 2021). The complications of bubble/spray generation were also largely avoided in these wind-wave conditions.…”

Future research perspective on the interfacial physics of non-invasive glaucoma testing in pathogen transmission from the eyes

“…High-frequency S waves being highly energetic dissipate quickly. In contrast, the capillary wave 77 is a low-frequency wave that forms on the surface of the tear film on the cornea. Capillary wave is caused by the interaction of the air puff with the tear film surface, and surface tension plays a significant role in determining the wave characteristics.…”

Periodic Waves and Ligaments on the Surface of a Viscous Exponentially Stratified Fluid in a Uniform Gravity Field

“…As it follows from the condition of the physical realization of the roots Re(k z ) > 0, considering the positive definite frequency of the wave motion, only one root, which is given by the expression (57), can be physically realized This solution describes the wave part of a periodic motion in a liquid.…”

“…The letter (W) indicates the dependencies for water and the letter (Gl) indicates the dependencies for glycerin. given by the expression (57), can be physically realized This solution describes the wave part of a periodic motion in a liquid.…”

“…The presence of a surfactant film dampens short capillary waves, which in turn amplifies decimeter waves [56]. The discussion of modern optical methods for studying capillary waves and the data of detailed experiments is carried out in [57]. A review of papers on the nonlinear interaction of coexisting waves of different frequencies within the framework of the theory of "wave turbulence" is presented in [58].…”