The effect of shear flow on the dendritic characteristics

Directional dendritic growth of transparent succinonitrile (SCN)-3.5wt.% H₂O alloy in the presence of shear flow is in-situ observed. The variation of dendritic characteristics, including growth tilting angle, primary arms spacing, and dendrite tip radius are quantitatively measured in wide flow rate (U) and pulling rate (V) regimes. The experimental data show that, the titling angle towards the upstream side is in proportional to (U/V) ^0.6. This could be explained by the reason that the dendritic growth process is mainly influenced by the solute diffusion competition between lateral direction and normal direction. Based on this, a mathematic model, which agrees well with the experimental data, is proposed to describe the correlation among the dendritic scales, shear flow rate and pulling rate.