Numerical simulation on fluid flow behavior during 3-dimensional dendrite growth with random preference angle

The flow behavior of three-dimensional(3D)dendrite growth with random preferred angle under natural convection was studied by using the Lattice Boltzmann-Cellular Automata(LB-CA)method with dynamic and static grids.In this model,the temperature field,flow field and solute field calculated by Lattice Boltzmann method(LBM)and dendrite growth calculated by CA method were carried out in static and dynamic grids respectively,and the coupling between LBM and CA was performed by interpolation of calculation parameters between dynamic and static grids.Results show that the asymmetry of solid phase distribution makes the streamline distribution more complex.At the initial stage of multiple dendrites growth,the fluid flow is relatively free.When dendrites grow close to each other,the fluid flow is blocked and can only flow along the gap between dendrites.During the wall equiaxed-columnar-central equiaxed crystals transformation(ECET)process,dense eddy current is formed at the wall equiaxed crystals at first.Then,when the wall equiaxed crystals gradually develop into columnar crystals,the eddy current moves with the solid-liquid interface.When the central equiaxed crystals are formed,the eddy current at the front of the columnar crystals gradually disappears.New eddies appear as the central equiaxed crystal grows.