A three-dimensional, first order turbulence closure, thermal diffusion mode
l is described in this paper. The governing equations consist of an equatio
n of continuity, three components of momentum, conservation equations for s
alt, temperature and subgridscale energy, and an equation of state. In the
model, according to the hypothesis of Kolmogorov and Prandtl, the viscosity
coefficient of turbulent flow of homogeneous fluid is related to the local
turbulent energy, and the horizontal and vertical exchange coefficients of
mass, heat and momentum are computed with the introduction of subgridscale
turbulence energy. The governing equations are solved by finite difference
techniques. This model is applied to the Jiaozhou bay to predict thermal p
ollution by the Huangdao power plant. An instantaneous tidal current field
is computed, then the distribution of temperature increment is predicted, a
nd finally the effect of wind stress on thermal discharge is discussed.