MODELING OF THE COUPLED MOTION OF RIGID BODIES IN LIQUID METAL

摘要

Casting processes often involve moving solid bodies that control the flow of metal, such as ladles and stoppers in gravity casting, shot pistons in pressure die casting and die components in squeeze casting. Simulation of these processes requires modeling the motion of the liquid metal, the solid bodies and the interaction between them. The present work describes a control-volume based model for general moving objects in fluids. Three-dimensional solid objects are modeled as rigid bodies moving through fixed rectangular grids. The location of the objects in the grid is described with fractional area and volume coefficients. New area and volume fractions are calculated at each time step using the updated object locations and orientations. The motion of each object can be either prescribed or dynamically coupled with fluid flow. For coupled motion, the motions of rigid bodies are governed by fluid, gravitational and control forces and torques. The action of a moving object on the fluid is modeled by introducing appropriate volumetric sources and sinks in each control volume that contains a moving surface. Tangential velocity of the moving object surface is also introduced into the shear stress terms of the momentum equations for the fluid. After validating the model against experimental data for drop tests of heavy simple-shaped objects in water, an example of liquid metal pouring simulation is also shown.