unstructured triangular grid

In this paper, a three-dimensional numerical model with high efficiency has been developed to simulate the flow around the abutment and bridge foundation. Since the focus of the developed model is to model the flow around river bridges, therefore, in all the different parts of the developed model, reducing the cost of calculations while maintaining the required accuracy is considered. The 3D model uses the finite volume and fractional step method on a grid without a triangular structure in the plan and with a structure in the vertical plane to solve the governing equations. In the numerical model, the transfer equation has been solved in the horizontal plane using the explicit method and in the vertical plane using the implicit method. Turbulence modeling is based on the mixed model, Smagorinsky in the plan and one-dimensional k-ε in the vertical direction. To consider the level of the free surface of water in the numerical model, only the pressure of the last layer has been determined by assuming hydrostatic pressure. To evaluate the model, the development of the three-dimensional boundary layer in the open channel has been tested. The comparison of the results obtained from the modeling of the flow around a bridge pier and the bridge deck with the laboratory results shows the appropriate accuracy and high efficiency of the developed three-dimensional model.