Effect of the liquid temperature on the interaction behavior for single water droplet impacting on the immiscible liquid

The interaction of single water droplet impacting on immiscible liquid surface was focused with the temperature varying from 50℃ to 210℃.The impact behavior is recorded with a high-speed camera running at 2000 frames per second.It is found that droplet diameter,oil temperature,andWeber number have important influences on impact behaviors.Three typical phenomena,including penetration,crater-jet,and crater-jet–secondary jet,were observed.Penetration only occurs when the Weber number is below 105.With Weber number increasing to 302,the jet begins to appear.Moreover,to gain deeper physical insight into the crater formation and jet formation,the energy of droplet impingement onto the liquid pool surface was estimated.The oil temperature has a significant effect on the energy conversion efficiency.High temperature is beneficial to improve energy conversion efficiency.

UNSTEADY WAVES DUE TO AN IMPULSIVE OSEENLET BENEATH THE CAPILLARY SURFACE OF A VISCOUS FLUID

The two-dimensional free-surface waves due to a point force steadily moving beneath the capillary surface of an incompressible viscous fluid of infinite depth were analytically investigated. The unsteady Oseen equations were taken as the governing equations for the viscous flows. The kinematic and dynamic conditions including the combined effects of surface tension and viscosity were linearized for small-amplitude waves on the free-surface. The point force is modeled as an impulsive Oseenlet. The complex dispersion relation for the capillary-gravity waves shows that the wave patterns are characterized by the Weber number and the Reynolds number. The asymptotic expansions for the wave profiles were explicitly derived by means of Lighthill’s theorem for the Fourier transform of a function with a finite number of singularities. Furthermore, it is found that the unsteady wave system consists of four families, that is, the steady-state gravity wave, the steady-state capillary wave, the transient gravity wave, and the transient capillary wave. The effect of viscosity on the capillary-gravity was analytically expressed.

Oblique Drop Impact on Deep and Shallow Liquid

Numerical simulations using CLSVOF(coupled level set and volume of fluid)method are performed to investigate the coalescence and splashing regimes when a spherical water drop hits on the water surface with an impingement angle.Impingement angle is the angle between the velocity vector of primary drop and the normal vector to water surface.The effect of impingement angle,impact velocity and the height of target liquid are carried out.The impingement angle is varied from 0o to 90o showing the gradual change in phenomena.The formation of ship pro like shape,liquid sheet,secondary drops and crater are seen.Crater height,crater displacement,crown height and crown angle are calculated and the change in the parameters with change in impingement angle is noted.