Effect of fluid fl ow on solidifi ed equiaxed dendrite morphology evolution based on phase fi eld - lattice Boltzmann method

Abstract

Fluid fl ow can signifi cantly change the evolution of microstructural morphology. However, relatively little is known how the fluid flow, concentration and microstructure affect each other quantitatively, which is essential to optimize processing parameters. A quantitative simulation study of Al-Cu solidifi ed equiaxed dendrite evolution under forced fl ow based on phase fi eld - lattice Boltzmann method (PF-LBM) is carried out. Results obtained are validated by Gibbs-Thomson relation at the dendrite tip. Compared with the equiaxed dendrite evolution without fl ow, the upstream dendrite arm is enhanced while the downstream arm is inhibited. Besides, as the inlet fl ow rate increases, the secondary arms attached onto the upstream primary arm and the upstream side of the primary arm normal to the infl ow velocity has been well developed. Results show that sidewise instabilities of the primary dendrite arm and onset of secondary arm is caused by the local concentration perturbation and will be enhanced or inhabited by the flow. It is believed that the coupled PF-LBM method is able to handle dendrite evolution under forced fl ow quantitatively, which helps in investigating the solidifi ed dendrite morphology evolution.

Keywords

• phase field
• lattice Boltzmann method
• forced fl ow