Transport processes in inland and coastal waters

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The dynamics of pollutant and sediment transports in inland and coastal waters are highly anisotropic with a tendency to two-dimensionality. The energy cascade, the reverse of the cascade, or a combination of both, between the 2D horizontal turbulence and small-scale 3D turbulence of distinct length scales are subjects of much interest, since the seminal work of Kraichnan (1967) on 2D turbulence. Laboratory data are needed to support not only the theoretical works but also the development of models. The Earth's rotation is a deciding factor in the large-scale exchanges. The small scale mixings across interfaces by turbulence are dependent on stability/instability of the density/gravity stratification. Research has been conducted by the applicant, his research associates and graduate students to study these 2D and 3D transport processes of very different time and length scales. Wind, wave and current effects on the processes are considered. The erosion and deposition of sediments are part of the study. The focus of the research has been on the fundamentals of modeling, and the verification of the models through laboratory and field studies. The research over the last six years has led to (i) the publication of 1 book, 1 book chapter, 1 book review, 1 editorial, 4 M.Eng. theses, 3 Ph.D. thesis and 43 papers, (ii) the development of instrumentation and data acquisition technique for velocity, temperature, salinity and tracer-concentration measurements, and (iii) the implementation of numerical methods for model simulations of turbulent flow. Future research will continue on the fundamentals. Greater emphasis of the research will be placed in the studying of the small-scale processes. Currently, a new channel is under construction for the planned study of the coastal erosion by waves and currents. The ongoing experiments in the wide channel for the large-scale exchanges will broaden to include cases of very large convective Froude number. The validation of the simulation models by experimental data will continue. The numerical effort will include the implementation of TVD schemes for the control of numerical oscillations, and the further development of a robust numerical method using the blocks as the computational elements.