Dynamics of self-rewetting drop on an inclined uniformly heated substrate

Abstract

The dynamics of a self-rewetting drop on a uniformly heated, inclined substrate are considered. Based on the lubrication theory and Navier slip condition, an evolution equation for the drop thickness of a two-dimensional drop is established. The migration characteristics of the drop are investigated when the interfacial tension is positive and negative and in a quadratic functional relationship with temperature under the same wetting scenario. The effects of the inclination angle, capillary number, Bond number, and thermocapillary force on the drop migration are examined when the interfacial tension has a nonmonotonic dependence on temperature. Numerical results indicate that the direction of interfacial tension has a significant influence on drop spreading. When the conventional pure fluid drop and self-rewetting fluid drop have the same wettability, the self-rewetting drop spreads more rapidly and the fluid is more evenly distributed on the inclined substrate. The effect of gravity parallel to the wall is enhanced by the increase in the inclination angle, resulting in faster drop sliding velocity. The increase in Ca results in a delay of the contact line pinning state and prolonged pinning time; however, the increase in Bo leads to an advanced pinning state of the contact line and reduced pinning time. The thermocapillary force is important to the deformation of the drop. When the enhancement in the thermocapillary force overcomes the effect of the other forces, less fluid is driven to flow down the wall, resulting in a relatively uniform distribution of the fluid on the substrate.