The Numerical Model Of Thermal Discharge From Houshi Power Plant

Houshi power plant is the largest power plant along the coast in China, and the thermal discharge from the plant will affect the adjacent water area in physics, chemistry, and biology to some extent. A numerical model, which using the alternating direction implicit, is applied to simulate the current field and temperature field in this area. ADI is a semi-implicit difference scheme and it bears both the advantage of explicit and implicit that easily computing and good stability.Firstly, the ADI numerical model is applied in an ideal bay, located in the northern hemisphere, with semi-closed boundary and equal depth. The figures of current field and temperature envelope at high water, low water, flood, ebb are respectively drawn according to the computation result. Because the result is in consistent with the theoretic analysis, the ADI numerical model is reasonable.Secondly, the model is applied in the adjacent water area of Houshi Power Plant. To better simulate the current field and temperature field in this area, the computation of small scope is nested into the large scope. The time step used in large scope is 124 seconds, and it is equal to four steps of small scope, which is 31 seconds; for space step, the space step used in large scope is 358.5 meters, which is equal to five space steps of small scope, 71.5 meters. The computation of large scope is stable after two periods, and then the computation of current in small scope starts. The boundary condition of small scope is provided by the computation result of large scope, and the computation is also stable after two periods. The computation of temperature field begins and it is stable after six periods. The computation is conducted at three different tide levels, including spring tide, still tideand neap tide. The figures of current field in large scope and small scope and temperature envelop in small scope at high water, low water, flood, ebb are respectively drawn according to the computation result.Finally, the figures of computation are compared with the figures drawn according to the surveyed data. The result of comparison shows that this numerical model is correct and reasonable.