Numerical Simulation For Flows And Temperature Near The Dam Area Of Three Gorges Reservoir

A three-dimension model coupled with flow and temperature is developed basedon Navier-Stokes equations for incompressible flows. The continuum-derivedPoisson equations are used to solve the pressure distribution and the momentumequations are used to solve the velocity components. Because the assumption of staticpressure of water is canceled, the model is appropriate for complex flows and densitylayered flows. The Finite Volume Method is adopted as the numerical discretizationmethod, the model has a fast computing velocity and it is applicable to engineering.Besides the buoyancy components considered in the momentum equations,anisotropic turbulent model is adopted in the model, such as Smagorinsky-DeardorffLarge Eddy Simulation, which enables the coupled flow and temperature can becomputed. The influence of the weather conditions is also considered in the model.The channel experiment which was made in 1980 by U.S Army EngineeringCorporation is adopted to investigate the validity and the reliability of the model. Theresults show that the computational results agree well with the results of theexperiments. It illustrates that the numerical model and the numerical methods cancorrectly predict the characteristics of thermal temperature flows.Some modes of heat exchange at the surface are considered. The radiant heat,humidity, air temperature, cloudage and wind speed are considered when computingthe heat exchange at the surface. Two conditions with different weather workingconditions are computed in a rectangle pool. The results show that the transfer of heatin the water agrees well with rules.The numerical model is applied to simulate the 3D-flow and temperature fieldsnear the Dam Area of Three Gorges Reservoir. The measured data is used as theboundary conditions in the entrance. Many different working conditions aresimulated from June 2003 to June 2004. The results show that the velocity of the flowbecomes larger at the narrow areas, the breadthwise distribution of the velocity isinfluenced by the underwater landform and the riverway. The computational watertemperature near the dam agrees well with the measured data. The temperature of thesame layer has little difference and the weather conditions have little influence on thetop layer. The layered temperature of the vertical did not occured. During thereservoir impoundment period with a 139m water level, although the air temperatureis high, it is difficult to form the layered temperature. It agrees well with thecomputational results.