Hostname: page-component-5c6d5d7d68-ckgrl Total loading time: 0 Render date: 2024-09-01T11:01:40.226Z Has data issue: false hasContentIssue false

Capillary–viscous forcing of surface waves

Published online by Cambridge University Press:  26 April 2006

John Miles
Affiliation:
Institute of Geophysics and Planetary Physics, University of California, San Diego, La Jolla, CA 92093, USA

Abstract

The linear excitation of straight-crested, capillary–gravity waves on the surface (x > 0) of a deep, viscous liquid in response to the sinusoidal, vertical motion of a hydrophilic wall at x = 0 is calculated on the assumptions that: (i) the dynamical variation of the contact angle is proportional to (but not necessarily in phase with) the velocity of the contact line relative to the wall; (ii) the relative tangential velocity (slip) of the fluid below the contact line is proportional to the shear at the wall, (iii) k0lv [Lt ] 1 and k0lc = O(1), where k0 is the wavenumber, lv is the boundary-layer thickness, and lc is the capillary length. The contact-angle and slip coefficients are complex functions of frequency that are found to be linearly related. Physical considerations suggest that the slip length ls (≡ slip velocity ÷ shear at wall) should be small compared with lv, which, in turn, implies that the motion of the contact line must be small in that parametric domain in which linearization provides a viable description of the wave motion near the wall; however, the analysis proceeds from (i) and (ii), qua phenomenological hypotheses, without a priori restrictions on the contact-line and slip coefficients. The present results include those of Wilson & Jones (1973), who assume that the amplitude and phase of the wave slope at the wall are prescribed, and those of Hocking (1987a), who assumes that the variation of the wave slope at the wall is in phase with the contact-line velocity and neglects viscosity. They also include a correction for the dynamical effects of the static meniscus, which is necessarily present for any static contact angle other than ½π but is neglected in the previous analyses, and have counterparts for the closely related problem (cf. Hocking 1987b) of the reflection of a plane wave from a stationary wall.

Type
Research Article
Copyright
© 1990 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Ablett, R.: 1923 An investigation of the angle of contact between paraffin wax and water. Phil. Mag. 46, 244256.Google Scholar
Benjamin, T. B. & Scott, J. C., 1979 Gravity–capillary waves with edge constraints. J. Fluid Mech. 92, 241267.Google Scholar
Hocking, L. M.: 1987a Waves produced by a vertically oscillating plate. J. Fluid Mech. 179, 267281.Google Scholar
Hocking, L. M.: 1987b Reflection of capillary–gravity waves. Wave Motion 9, 217226.Google Scholar
Jewell, D. A.: 1967 Unsteady flow of a viscous liquid at the intersection of a solid boundary and a free surface. Ph.D. dissertation, University of California, Berkeley.
Lamb, H.: 1932 Hydrodynamics. Cambridge University Press.
Mahony, J. J. & Pritchard, W. G., 1980 Wave reflexion from beaches. J. Fluid Mech. 101, 809832.Google Scholar
Miles, J. W.: 1967 Surface-wave damping in closed basins. Proc. R. Soc. Lond. A 291, 459475.Google Scholar
Miles, J. W.: 1990 Wave, motion in a viscous fluid of variable depth. J. Fluid Mech. 212, 365372.Google Scholar
Ngan, C. G. & Dussan, V. E. B. 1989 On the dynamics of liquid spreading over solid surfaces, J. Fluid Mech. 209, 191206.Google Scholar
Smith, S. H.: 1968 On the creation of surface waves by viscous forces. Q. J. Mech. Appl. Maths 21, 439450.Google Scholar
Wilson, S. D. R. & Jones, A. F. 1973 Surface waves produced by viscous forces. Q. J. Mech. Appl. Maths 26, 339345.Google Scholar
Young, G. W. & Davis, S. H., 1987 A plate oscillating across a liquid interface: effects of contact-angle hysteresis. J. Fluid Mech. 174, 327356.Google Scholar