CFD Application in 3D flow filed modeling of a large dam reservoir

In the present paper, a 3D numerical model has been applied to predict the flow hydrodynamics around power intakes within the Dez dam reservoir. The Dez dam is a 203 m high, double arch concrete dam which is constructed by Italians in 1962. Since then, sedimentation in reservoirhas continued and since the dam does not have bottom outlet, the reservoir bed level is raising by a rate of about 2.5 meter per year. The power intake invert level is in 270 m asl and on the basis of 2007 hydrography results, the reservoir bed level has reached the level of 260 m asl that means the sediment level is just 10 meters below the power tunnel intakes. The applied three dimensional model is a finite volume model, which can model curvilinear and non-orthogonal domains and uses the fully 3D time averaged Navier Stocks equations. For incorporating the effects of turbulent flow in computations, an advanced turbulent model, named k −w model has been applied. The present model results for flow field around power intakes show that for the present conditions (sediment level of 260 m and intakes level of 270 m) some limited amount ofsediments is entering power tunnels and if no rehabilitation measures is considered, more sediment will enter the power tunnels in the coming years.