A TIDAL THREE-DIMENSIONAL NONLINEAR MODEL WITH VARIABLE EDDY VISCOSITY (Ⅰ)——A DYNAMIC MODEL

A three-dimensional non-linear model of tides was proposed by one of the authors（1977）.Later the model was applied to modeling two principal first-order constituentsMand MSof shallow water in the Bohai Sea（1981）.As pointed out in the reference[1],however,the model has physically a main weakpoint in the hypothesis about the eddyviscosity v,i.e.,v=v（x,y）was considered to be irrelative to both the nondimensional verticalcoordinate z and the tidal current structure,where（x,y）are nondimensional horizontalcoordinates.No doubt,the non-linear model of tides,which only involves the nonlineareffects of both the convection acceleration in the equation of motion and the kinematicboundary condition at the free surface,is not completely nonlinear one.The effect of variable