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Wind waves and diffusion in open channels




Su, Kuo-Shyong, author
Gessler, Johannes, author
Fluid Dynamics and Diffusion Laboratory, Colorado State University, publisher

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This study describes a theoretical and experimental investigation of the vertical and lateral mixing of tracer fluids in a straight, wide, open channel, with and without wind action on the water surface. Using appropriate assumptions and simplifications, a three-dimensional vertical-and lateral-mixing equation suitable for any channel geometry and source distribution is first derived. The experiments were conducted in a two-ft wide wind-water tunnel with and without wind effects. Velocity fields were measured in detail in both cases. Evaluated vertical diffusion coefficients from the measured velocity profiles served as a first approximation to the numerical analysis of the diffusion equation. A specially designed single-electrode conductivity probe-and hot-film sensor was used to measure point velocity and concentration fluctuations from which the covariances of the concentration and longitudinal component of velocity were calculated to evaluate the longitudinal diffusion coefficients. Wave data were recorded and analyzed to relate the water surface properties with the diffusion process. Concentration profiles of the tracer were obtained in cross-sections at various distances downstream from the source. The data were used to evaluate the vertical and lateral mixing coefficients by a simulation method. The results indicated that the vertical mixing rates were significantly increased when waves appear on the water surface, the rate of lateral mixing was slightly decreased and the tracer plume was found to deflect downward in the mixing process although the tracer was neutrally buoyant.


May 1972.
Includes bibliographical references (pages 106-108).
Prepared under contract no. At (11-1) - 1813, Atomic Energy Commission, Fallout Studies Branch.

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Wind waves
Fluid dynamics -- Mathematical models
Channels (Hydraulic engineering)


Associated Publications