Santi Charuskumchornkul creator Suphat Vongvisessomjai Chairperson Tawatchai Tingsanchali Examination Committee Preecha Kamronrithisorn Examination Committee The Asian Institute of Technology Alumni Association (AITAA), Scholarship Donor text th Bangkok Asian Institute of Technology 1988 monographic eng

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144 p. In recent years, there has been a· growing concern about water quality problems associated with tidal convection and circulation in harbours and shallow estuaries, particularly in the planning and design stages of modifications . Presently, with the advancement in computer applications and the deve lopment of numerical techniques, economies in time and effort have made computer modelling a viable alternative . Many efforts have been made with the numerical models which are more remarl{able and advantageous than both analytical and hydraulic models, with respect to flexibility, because the actual flow patterns and nonlinearity in boundary geometry can be used in the computational processes . Although such models do exist, a comprehensive analysis of the individual mechanisms which interact to produce circulation has not been attempted with a numerical model . This study seelrn to identify the behavioral differences caused by a particular selection of discretization parameters and boundary conditions . The depth-averaged two-dimensional model is performed to study the phenomena of tidal circulation in a discrete representation of a continuum problem, a variety of computational procedures and boundary conditions in the model are available . By using the so-called "Alternating Direction Implicit" (ADI) finite difference scheme , a combination of implicit and explicit schemes, the numerical model is developed to achieve the proposed problems . In this study, the model is applied to three partlcuJar areas of interest namely ; The whole Upper Gulf of Thailand, The Chao Phraya river mouth and Laem Chabang Port . The details of tidal circulation are presented according to the four predominant tidal constituents namely ; M2,S2,Kl and 01 constituents as well as all th~ four constituents . To test its reliability, the calibration of the model to the current system is performed and shows the satisfactory comparison between the computed values and predicted values of tide level obtained by the Harmonic Analysis . Taken into account is the verification of the model to the hourly tidal current data measured by the Hydrographic Department in 1973 . The verification was accomplished by the well simulated situation of computed values and better tendency to improve . The obtained results from this numerical model give the different circulation patterns under such interferences . Furthermore, the effects of shoreline, river and open sea boundary are also closely investigated, particularly at the river mouth . From the macro viewpoint, the river boundary is considered as the well simulated situation of computed values of water level, compared with the shoreline boundary . In the micro viewpoint, the contribution of river and shoreline boundary to the current field can predominate only in the neighborhood of coastline at some extents, whereas the open sea boundary, the assigned boundary values are the major factor controlling the simulated situation of computed values of current field . In addition to this, the effect of freshwater flow and the restriction of the coastline configuration are also affected to those computed values . A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology Thesis (M.Eng.) - Asian Institute of Technology, 1988 Oceanography Thailand, Gulf fo Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B18851 http://203.159.5.9/ait-thesis/detail.php?q=B18851 050698 20260818170411.0