Experimental Study of Wave‐Induced Longitudinal Vortices
Publication: Journal of Hydraulic Engineering
Volume 117, Issue 12
Abstract
Wind‐driven currents in estuaries, lakes, and the ocean are often observed to include strong longitudinal vortices, known as Langmuir cells. To test experimentally the theory developed by Craik and Leibovich that these cells arise through wave‐current interactions, we superimposed mechanically generated waves on a turbulent channel flow. Our results show that streamwise vortices can form through wave‐current interaction described by Craik and Leibovich: The vertical component of the mean vorticity can be rotated by the sheared Stokes' drift current of the waves to produced longitudinal vorticity. In the present configuration, the main sources of vertical vorticity are the boundary layers on the sides of the channel. Nonetheless, given the fact that longitudinal vortices like these enhance mixing, our experiments suggest that wave‐current interactions can contribute significantly to near‐surface mixing in many water bodies. Thus, the connection between waves and mixing that Keulegan and Brame sought to make when they studied mixing by wind waves does seem to exist, albeit with a somewhat different physical basis than they described.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
Cheung, T., and Street, R. L. (1988). “The turbulent layer in the water at an air‐water interface.” J. Fluid Mech., 194, 133–154.
2.
Craik, A. D. D. (1982). “Wave induced longitudinal vortex instability in shear flows.” J. Fluid Mech., 125, 37–52.
3.
Crawford, G. B., and Farmer, D. V. (1987). “On the spatial distribution of ocean bubbles.” J. Geophys. Res., 92(C8), 8231–8243.
4.
Faller, A. J. (1969). “The generation of Langmuir circulations by the eddy pressure of surface waves.” Limnol. Oceanog., 14(4), 504–513.
5.
Faller, A. J., and Caponi, E. A. (1978). “Laboratory studies of wind‐driven Langmuir circulations.” J. Geophys. Res., 83(7), 3617–3633.
6.
Gargett, A. E. (1989). “Ocean turbulence.” Ann. Rev. Fluid Mech., 21, 419–452.
7.
Gulliver, J. S. and Halverson, M. J. (1989). “Air‐water gas transfer in open channels.” Water Resour. Res., 25(8), 1783–1794.
8.
Jiang, J. Y., Street, R. L., and Klotz, S. P. (1989). “Wave‐turbulence interaction beneath an air‐water interface.” Proc. Seventh Turbulent Shear Flows Symp., Stanford University, Aug.
9.
Keulegan, G. H., and Brame, V. (1960). “Fourteenth progress report on model laws for density currents: Mixing effects of wind‐induced waves.” Report NBS 6638, Nat. Bureau of Standards, Washington, D.C.
10.
Langmuir, I. (1938). “Surface motion of water induced by wind.” Science, 87, 119–123.
11.
Leibovich, S. (1977). “On the evolution of the system of wind drift currents and Langmuir circulations in the ocean. Part 1. Theory and averaged current.” J. Fluid Mech., 79(4), 715–743.
12.
Leibovich, S. (1983). “The form and dynamics of Langmuir circulations.” Ann. Rev. Fluid Mech., 15, 391–427.
13.
Leibovich, S., and Paolucci, S. (1980). “The Langmuir circulation instability as a mixing mechanism in the upper ocean.” J. Phys. Ocean., 10, 186–207.
14.
Monismith, S. G. (1986). “An experimental study of the upwelling response of stratified reservoirs to shear stress.” J. Fluid Mech., 171, 407–439.
15.
Peerhossaini, H., and Wesfried, J. (1988). “On the inner structure of Görtler rolls.” Int. J. Heat Fluid Flow, 9(1), 12–18.
16.
Smith, J., Pinkel, R., and Weller, R. A. (1987). “Velocity structure in the mixed layer during MILDEX.” J. Phys. Ocean., 17, 425–439.
17.
Weller, R. A., and Price, J. F. (1988). “Langmuir circulations within the oceanic mixed layer.” Deep Sea Res., 35(5), 711–747.
Information & Authors
Information
Published In
Copyright
Copyright © 1991 ASCE.
History
Published online: Dec 1, 1991
Published in print: Dec 1991
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.