In order to obtain the unique solution of hydrodynamics, not only the above basic equations, but also the boundary conditions and initial conditions need to be given.
Initial condition
Because of the unsteady flow of liquid metal in the filling process, the pressure field and velocity field of liquid metal can be solved only when the initial temperature and velocity distribution of the mold are given. The initial injection velocity is 2 m · s – 1, the suitable pouring temperature of the material used is 900 ～ 953k, and the initial temperature of the mold is set at room temperature.
Boundary condition
The boundary conditions are the flow parameters that need to be satisfied when the fluid flows on the boundary. The commonly used boundary conditions of fluid flow include solid-solid interface, gas-liquid interface and liquid-liquid interface condition. A) solid-liquid interface: when viscous fluid flows through a stationary solid interface, its normal velocity should be equal to zero. b) Liquid liquid and liquid gas interfaces: if the interfaces of the two media are impermeable to each other and do not meet the continuity condition of no separation, the normal velocity at the interface is equal. For viscous fluid, the tangential velocity and temperature should be equal at the interface of the two media, but not in the ideal fluid. In addition to the plane of the feed inlet, the other plane node velocities are set to zero in X, y, z directions. Because the side casting gating system is selected as the gating system in this work, the pouring speed is set on the plane of the feeding port, and the size is set as 1-5cm · s-1.