Modeling sessile droplet dynamics in channel flow.

摘要

Dynamics of a sessile droplet in channel flow is studied numerically. The numerical model uses one set of the governing equations combined with a volume tracking method on a fixed structured mesh to model the simultaneous movement of mass and momentum across cell boundaries. Surface tension is modeled as a body force acting on the fluid near the free surface.;Two dimensional sessile droplet deformation and channel flow structures are discussed for both pinned and unpinned droplets. The effects of having a fixed contact line on the deformation and breakup of a droplet are investigated. A characteristic length is defined to compare droplet deformation due to changes in the surface tension, viscosity and density ratios. Among theses parameters, the surface tension is found to be the most important one in determining the mobility of the droplets. A breakup criterion is obtained in terms of droplet Reynolds and Capillary numbers.;Next, dynamics of two spaced sessile droplets in a channel flow is investigated. Displacements of binary droplets in a channel flow are compared by studying changes in the location of the leading and trailing edges for each droplet at different droplet spacing. Deformation and displacement of leading and tailing droplets with the ones for a single droplet are presented.;The thesis concludes with application of the model to study displacement of a three-dimensional droplet. Dynamics of channel flow at the presence of water droplet was investigated considering the effects of Reynolds Number, Capillary number, Bond number, droplet size, and the contact angle. Displacement was characterized based on the changes of the droplet height and the contact wetted area.