The studied domain, the whole Gulf of Tonkin, extends from the coastal zone of Quang-Ninh into ThuaThienHue province and as far as Hai-Nam (China) island seawards. The model have been calibrated and verified by the observed data at six different stations for a three and seven-day periods. The results are in good agreement with the obseved data. The kinetic energy distribution was eonsidered. | Vietnam Journal of Mechanics, NCST of Vietnam Vol. 23, 2001, No 2 (116 - 128) 3-D NUMERICAL SIMULATION OF THE TIDAL CIRCULATION IN THE GULF OF TONKIN, VIETNAM PHAN NGOC VINH(l), NGUYEN KIM DAN( 2) (l) , where n is the angular frequency of earth rotation and¢ is latitude of the studied location; KM is the vertical turbulent viscosity coefficient; Fx, Fy are the horizontal diffusivities, which are defined as follows: () where, AM is the horizontal turbulent diffusivity, which is assumed constant in the present study. 2. Initial conditions At the initial time t = 0, velocity components of u, v, w, surface water level rt and other variables are given. 117 3. Boundary conditions - At the water surface: () - At the bottom: (3 .2) wher~, Us, Vs, Ws are velocity components at the water surface; ·ub, vb, wb are velocity components at the bottom; (Tsx , Tsy) is wind stress at the water surface and (Tbx, Tby) is bed shear stress; 77 is the water surface elevation; h is the bottom depth. - At the land boundary: The velocity co:m,ponents normal to walls are null, . Un = 0. In addition, for the tangential component of velocity, a no-slip condition at the wall is used. - At the open _!)Oundary: Commonly, at the open boundaries, tide surface elevation is a priori prescribed as Dirichlet's conditions at all times. 4. Turbulent closure sub-model K-L The governing equations contain the parameterized Reynolds stress and the flux terms, which take into account the turbulent diffusion of momentum, salt. The parameterization of turbulence in the model described here is based on the work of Li et al. (1997). This is an one equation sub-model, in which the turbulence kinetic energy, k has been determined from a transport equation as follows: 8k 8k 8k 8k at+ u -ax+ v -8y+ w -=2KM az [(8u)2 ._ + (8v)2] - az a ( 8k) 2gKzs 8p +-KM- +----E+Fk 8z 8z Po 8z with az () Fk = :x (AH~~) + :y (AH~~) and the turbulent mixing length, L has been computed from the following .
