DU Yuxuan, MIN Qi, LI Yanzhi, DU Jiayu
Previous research on droplet impact dynamics has yielded different results, and the types of fluids studied are not sufficiently diverse. This project numerically modeled droplet impact dynamics with nine kinds of fluids including water, glycerite, silicone oil, and liquid metals at room temperature with viscosities of 1-970 mPa·s and surface tensions of 20-500 mN/m. The phase-field model was used to supplement the data at low Reynolds numbers to explore the applicability of existing theories. The results show that at the beginning of the impact, the existing law for the spread factor, β, varying with the dimensionless time, τ, is applicable for Re>100. The simulation results are consistent with existing theory that the maximum spread factor, βmax, scales as βmax∝Web in the capillary regime and βmax∝Reb in the viscous regime. The effect of wall wettability on the exponent b was also analyzed. The minimum center thickness, hmin*, is consistent with the existing theory of hmin*∝Re-0.5 only when We ≥ 10. For We < 10, the wall wettability and surface tension strongly influence hmin*. As Re tends to 1, βmax and hmin* are determined by the initial kinetic energy of droplet and wettability of target surface, but they deviate from the above power function laws.
