Entrainment and Turbulence in Saline Underflow in Lake Ogawara
Publication: Journal of Hydraulic Engineering
Volume 127, Issue 11
Abstract
Under certain tidal conditions, a saline underflow originating in the Pacific Ocean moves into Lake Ogawara, Japan. The underflow consists of a uniform saline bottom layer that is slightly warmer than the ambient and an interfacial shear layer in which the velocity and density are decreased. Within the experimental area the underflow is confined to a channel approximately 1 km wide and is essentially two-dimensional. The underflow had a bulk Richardson number, defined in terms of the mean properties, between 1 and 2. The rate of entrainment into the bottom layer was calculated using two distinct methods. The first method used the change in the maximum salinity of the underflow measured at two stations along the path of the underflow to infer the amount of ambient water entrained. The second method made direct measurements of vertical mass fluxes with a profiler. The agreement between the two methods was excellent. The measured entrainment coefficients were consistent with the derived entrainment law. The turbulent structure of the flow was mapped for a 3 h quasisteady period of the flow. Turbulence is predominantly generated on the bottom boundary and is transported vertically to the density interface, where it leads to mixing.
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References
1.
Alavian, V. (1986). “Behavior of density currents on an incline.”J. Hydr. Engrg., ASCE, 112(1), 27–42.
2.
Alavian, V., Jirka, G. H., Denton, R. A., Johnson, M. C., and Stefan, H. G. (1992). “Density currents entering lakes and reservoirs.”J. Hydr. Engrg., ASCE, 118(11), 1464–1489.
3.
Altinakar, M. S., Graf, W. H., and Hopfinger, E. J. (1996). “Flow structure in turbidity currents.”J. Hydr. Res., 34(5), 713–719.
4.
Atkinson, J. F., and Harleman, D. R. F. ( 1987). “Wind-mixing experiments for solar ponds.” Solar Energy, 38(6), 389–403.
5.
Briggs, D. A., Ferziger, J. H., Koseff, J. R., and Monismith, S. G. ( 1996). “Entrainment in a shear-free turbulent mixing layer.” J. Fluid Mech., Cambridge, U.K., 310, 215–241.
6.
Britter, R. E., and Linden, P. F. ( 1980). “The motion of the front of a gravity current travelling down an incline.” J. Fluid Mech., Cambridge, U.K., 99(3), 531–543.
7.
Britter, R. E., and Simpson, J. E. ( 1978). “Experiments on the dynamics of a gravity head.” J. Fluid Mech., Cambridge, U.K., 88(2), 223–240.
8.
Chow, V. T. ( 1973). Open channel hydraulics, Int. Student Ed., McGraw-Hill, New York.
9.
Christodoulou, G. C. (1986). “Discussion of `Interfacial mixing in stratified flows' by J. P. Urambert.”J. Hydr. Res., ASCE, 24(2), 77–87.
10.
Dewey, R. K., and Crawford, W. E. ( 1988). “Bottom stress estimates from vertical dissipation rate profiles on the continental shelf.” J. Phys. Oceanography, 18(8), 1167–1177.
11.
Elder, R. A., and Wunderlich, W. P. ( 1972). “Inflow density currents in TVA reservoirs.” Int. Symp. on Stratified Flows, ASCE, 221–236.
12.
Ellison, T. H., and Turner, J. S. ( 1959). “Turbulent entrainment in stratified flows.” J. Fluid Mech., Cambridge, U.K., 6(3), 423–448.
13.
Fischer, H. B., List, E. J., Koh, R. C., Imberger, J., and Brooks, N. H. ( 1979). Mixing in inland and coastal waters, Academic, New York.
14.
Fleury, R. C., and Leuck, R. C. ( 1994). “Direct heat flux estimates using towed vehicle.” J. Phys. Oceanography, 24, 801–818.
15.
Fozdar, F. M., Parker, G., and Imberger, J. ( 1985). “Matching temperature and conductivity sensor response characteristics.” J. Phys. Oceanography, 15(11), 1557–1569.
16.
Fredsoe, J., and Deigaard, R. ( 1994). Mechanics of coastal sediment transport, World Scientific, Singapore.
17.
Gordon, C. M., and Witting, J. ( 1977). “Turbulent structure in a benthic boundary layer.” J. Nihoul, ed. Bottom turbulence, Elsevier, Amsterdam.
18.
Hallworth, M. A., Herbert, E. H., Phillips, J. C., and Sparks, R. S. ( 1996). “Entrainment into two-dimensional and axisymmetric turbulent gravity currents.” J. Fluid Mech., Cambridge, U.K., 308, 289–311.
19.
Hebbert, B., Patterson, J., Loh, I., and Imberger, J. (1979). “Collie River overflow into the Wellington reservoir.”J. Hydr. Div., ASCE, 105(5), 533–545.
20.
Hendricks, P. J., and Rodenbusch, G. ( 1981). “Interpretation of velocity profiles measured by freely sinking probes.” Deep-Sea Res., 28A(10), 1199–1213.
21.
Huntley, D. A. ( 1988). “A modified inertial dissipation method for estimating seabed stresses at low Reynolds numbers, with application to wave/current boundary layer measurements.” J. Phys. Oceanography, 18(2), 339–346.
22.
Imberger, J., and Boashash, B. ( 1986). “Application of the wigner-ville distribution to temperature gradient microstructure: A new technology to study small scale variations.” J. Phys. Oceanography, 16(12), 1997–2012.
23.
Imberger, J., and Head, R. ( 1994). “Measurement of turbulent properties in a natural system.” C. A. Pugh, ed. Fundamentals and advancements in hydraulic measurements and experimentation, ASCE, New York, 1–20.
24.
Ivey, G., and Imberger, J. ( 1991). “On the nature of turbulence in a stratified fluid. 1: The energetics of mixing.” J. Phys. Oceanography, 21(5), 650–658.
25.
Kneller, B. C., Bennett, S. J., and McCaffrey, W. D. ( 1999). “Velocity structure, turbulence and fluid stresses in experimental gravity currents.” J. Geophys. Res., 104(3), 5381–5391.
26.
Lofquist, K. ( 1960). “Flow and stress near an interface between stratified liquids.” Physics of Fluids, 3(2), 158–169.
27.
Luketina, D., and Imberger, J. ( 1989). “Turbulence and entrainment in a buoyant surface plume.” J. Geophys. Res., 94(9), 12619–12636.
28.
Morton, B. R., Taylor, G. I., and Turner, J. S. ( 1956). “Turbulent gravitational convection from maintained and instantaneous sources.” Proc., Royal Soc., London A, 234, 1–23.
29.
Moum, J. N. ( 1990). “The quest for kr preliminary results from the direct measurement of turbulent fluxes in the ocean.” J. Phys. Oceanography, 20(12), 1980–1984.
30.
Nagao, M., and Ishikawa, T. ( 1995). “Entrainment coefficient of inclined plume on the bottom slope of Lake Ogawara field experiments in 1992 and 1993.” Tech. Rep., Dept. of Civ. Engrg., Tokyo Institute of Technology.
31.
Nakos, J. T. ( 1994). “The prediction of velocity and temperature profiles in gravity currents for use in chilled water storage tanks.” J. Fluids Engrg., 116(1), 83–90.
32.
Oldham, C. E., and Lavery, C. E. ( 1999). “Porewater nutrient fluxes in a shallow fetch-limited estuary.” Marine Ecology Progress Ser., 183, 39–47.
33.
Piccirillo, P., and Van Atta, C. W. ( 1997). “The evolution of a uniformly sheared thermally stratified turbulent flow.” J. Fluid Mech., 334, 61–86.
34.
Saggio, A., and Imberger, J. ( 2001). “Mixing and turbulent fluxes in a metalimnion of a stratified lake.” Limnology and Oceanography, 46(2), 392–409.
35.
Sherman, F. S., Imberger, J., and Corcos, G. M. ( 1978). “Turbulence and mixing in stably stratified waters.” Annu. Rev. Fluid Mech., 10, 267–288.
36.
Simpson, J. E. ( 1969). “A comparison between laboratory and atmospheric density currents.” Quarterly J. Royal Meteorological Soc., Bracknell, U.K., 95, 758–765.
37.
Simpson, J. E. ( 1997). Gravity currents in the environment and in the laboratory, 2nd Ed., Cambridge University Press, Cambridge, U.K.
38.
Simpson, J. E., and Britter, R. E. ( 1979). “The dynamics of the head of a gravity current advancing over a horizontal surface.” J. Fluid Mech., 94(3), 477–495.
39.
Tennekes, H., and Lumbley, J. L. ( 1972). A first course in turbulence, MIT Press, Cambridge, Mass.
40.
Thorpe, S. A. ( 1977). “Turbulence and mixing in a Scottish loch.” Philosophical Trans. Royal Soc., London, Ser. A. 286, 125–181.
41.
Winters, K. B., and D'Asaro, E. A. ( 1996). “Diascalar flux and the rate of fluid mixing.” J. Fluid Mech., 317, 179–193.
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Received: May 3, 2000
Published online: Nov 1, 2001
Published in print: Nov 2001
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