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The possibility of coalescence between rolling and static droplets is greater than that of static droplets. Due to the randomness of the velocity direction of rolling droplets and the position of static droplets, rolling and static droplets are more prone to non-frontal coalescence. Most studies focused on static droplets or head-on coalescence jumping, while non-frontal coalescence is poorly understood. In this work, we experimentally and numerically study the head-on and non-frontal coalescence of a rolling droplet and a static one. Furthermore, to measure the jumping characteristics of merged droplets, a "single camera defocusing imaging measurement" (SCDIM) method was proposed to obtain a 3D trajectory of the jumping droplet. For non-frontal coalescence, the morphological evolution of the merged droplet rotates counterclockwise during the coalescence process. The direction of horizontal jumping velocity deviates towards the rolling droplet. The non-frontal deviation and initial velocity determine whether rotation can occur and its strength. The higher initial velocity has a negative impact on the jumping velocity in the Z direction with the increase of non-frontal deviation, while the deviation angle could be negligible. As the non-frontal deviation ratio increases, the dominant mechanism of coalescence jumping is gradually transferred from the impact effect to the contraction of the merged droplets. Different from jumping velocity in the Z direction, the horizontal jumping velocity is approximately proportional to the dimensionless initial velocity. [Display omitted] [ABSTRACT FROM AUTHOR]

The stability of liquid marbles is critical to their application in sensors, microfluidic control, microreactors, and other fields. A more comprehensive understanding of the rupture kinetics of liquid marble is instructive for studies in improving the stability of liquid marble. However, the mechanism of rupture of liquid marbles is not clear at present, therefore, this paper addressed this issue by calculating the displacement of particles on the surface of a liquid marble using the DIC (Digital Image Correlation) algorithm. The distribution characteristics of the particles on the surface of the liquid marble and their movement patterns were clarified, the causes of cracks on the marble surface were analyzed, the mechanism of liquid marble rupture was derived, and the effect of volume on rupture kinetics was analyzed. Based on the obtained data, a method was proposed to control the maximum compression that the liquid marble can withstand by spraying different sizes of superhydrophobic coatings. This paper contributes to the study of the stability of liquid marble, allowing its wider application in industrial production. [Display omitted] • Particle displacements on the surface of liquid marbles were accurately measured by the DIC algorithm. • The displacement patterns of particles on the surface of liquid marbles and the causes of their cracks were analyzed. • The effect of the volume of the liquid marbles on the cracking mechanism was analyzed. • The maximum compression that liquid marble can withstand was controlled by different sizes of superhydrophobic coating. [ABSTRACT FROM AUTHOR]