Effects of natural and forced convections on dendritic growth in thin-walled Al-Cu alloy by counter-gravity casting: A phase-field lattice-Boltzmann study

• Coupled lattice Boltzmann and phase-field model accurately simulates dendritic growth under combined natural and forced convection in thin-walled Al-Cu alloys. • Convection breaks dendritic symmetry: equiaxed crystals show solute plumes and asymmetric arms, while columnar dendrites exhibit an optimal applied force for refined microstructure. • Forced convection consistently reduces the inclination angle of primary dendrites, offering a control lever for CGC process optimization. • Findings provide validated theoretical guidance for improving counter-gravity casting of thin-walled aerospace components.