A dissertation submitted in partial fulfillment of the requirements for the degree of Doctoral Technical Science

Thesis (Ph.D.) - Asian Institute of Technology, 1977

A mathematical model is herein developed to predict the tide motion frOm the relationship between the harmonic constants of the tide and tidal current. The tidal motion is firstly described, based on the Navier Stokes{u2018} equations of motion and the continuity equation. These equations are linearized to obtain a quasi steady state solution for each tidal con stituent by finite difference method with implicit and explicit schemes. Forces considered are inertia, Coriolis, pressure gradient and friction. The model is then applied to the Gulf of Thailand in which techniques of assuming boundary conditions at open entrance are required. Results are then compared with solution obtained by superposing two Kelvin waves with different amplitude in opposite direction as well as with solution of Taylor (1920). Discussions are made with regard to the relative com patibilities and discrepancies of the results. It is found that non-linear distribution of tidal harmonic constants along the boundary is more reliable than the linear type and that the Kelvin wave solution can be extended to depict the phenomena of shifting of the amphidromiC point at centre of a nodal line to one side of the Gulf. A tidal current prediction method is next developed by establishing the relationship between the harmonic constants of the tide and those of the tidal current2 This aspect lends itself readily to the prediction of tidal current field, using only a small amount of tide and tidal current data. Results are verified for the case of Sattahip Bay, Thailand.