In this study, porosity was introduced into two-dimensional shallow water equations to reflect the effects of obstructions, leading to the modification of the expressions for the flux and source terms. An extra porosi...In this study, porosity was introduced into two-dimensional shallow water equations to reflect the effects of obstructions, leading to the modification of the expressions for the flux and source terms. An extra porosity source term appears in the momentum equation. The numerical model of the shallow water equations with porosity is presented with the finite volume method on unstructured grids and the modified Roe-type approximate Riemann solver. The source terms of the bed slope and porosity are both decomposed in the characteristic direction so that the numerical scheme can exactly satisfy the conservative property. The present model was tested with a dam break with discontinuous porosity and a flash flood in the Toce River Valley. The results show that the model can simulate the influence of obstructions, and the numerical scheme can maintain the flux balance at the interface with high efficiency and resolution.展开更多
The complicated flow structure around the pier threatens the safe navigation of ships.This paper studies the mechanism of the flow with a ship around the pier,passing or not passing and with consideration of the inter...The complicated flow structure around the pier threatens the safe navigation of ships.This paper studies the mechanism of the flow with a ship around the pier,passing or not passing and with consideration of the interval between the ship and the pier.The flow field model and the moving ship model are constructed by the six degrees of freedom(6DOF)solver combined with the virtual unit immersed boundary method and the level set method,both of which are based on the three-dimensional Navier-Stokes equations.The simulation results show that the ship significantly influences the flow around the pier,increasing the flow velocity by 50%to 140%.Away from the bridge pier,the cross-flow velocity decreases.The cross-flow velocity near the side of the pier also increases but in the opposite direction.The ship is affected by the negative yaw moment because of the reverse cross-flow between the pier and the ship.The size of the ship has an important impact on the extent of the affected flow areas but the velocity distribution is roughly in the same shape.The results show double impacts of ship and pier should be considered when determining the safe area of navigation.展开更多
基金supported by the National Natural Science Foundation of China (Grants No. 50909065 and 51109039)the National Basic Research Program of China (973 Program, Grant No. 2012CB417002)
文摘In this study, porosity was introduced into two-dimensional shallow water equations to reflect the effects of obstructions, leading to the modification of the expressions for the flux and source terms. An extra porosity source term appears in the momentum equation. The numerical model of the shallow water equations with porosity is presented with the finite volume method on unstructured grids and the modified Roe-type approximate Riemann solver. The source terms of the bed slope and porosity are both decomposed in the characteristic direction so that the numerical scheme can exactly satisfy the conservative property. The present model was tested with a dam break with discontinuous porosity and a flash flood in the Toce River Valley. The results show that the model can simulate the influence of obstructions, and the numerical scheme can maintain the flux balance at the interface with high efficiency and resolution.
基金Project supported by the National Key Research and Development Program of China(Grant No.2018YFB1600400)the Jiangsu Province Transportation Science and Technology Project(Grant No.2018Y20).
文摘The complicated flow structure around the pier threatens the safe navigation of ships.This paper studies the mechanism of the flow with a ship around the pier,passing or not passing and with consideration of the interval between the ship and the pier.The flow field model and the moving ship model are constructed by the six degrees of freedom(6DOF)solver combined with the virtual unit immersed boundary method and the level set method,both of which are based on the three-dimensional Navier-Stokes equations.The simulation results show that the ship significantly influences the flow around the pier,increasing the flow velocity by 50%to 140%.Away from the bridge pier,the cross-flow velocity decreases.The cross-flow velocity near the side of the pier also increases but in the opposite direction.The ship is affected by the negative yaw moment because of the reverse cross-flow between the pier and the ship.The size of the ship has an important impact on the extent of the affected flow areas but the velocity distribution is roughly in the same shape.The results show double impacts of ship and pier should be considered when determining the safe area of navigation.
