Deflection of microjets induced by asymmetric heating and related free surface flows with moving contact lines

Jayanta Chandana Panditaratne, Purdue University


While small-scale viscous free surface flows are fundamentally challenging because of their complexity, they are also industrially important due to their widespread occurrence in engineering applications such as inkjet printing, genomic analysis and gravure and roll coating. All free surface flows are distinguished by the fact that at least a portion of the boundary enclosing the region in which the flow takes place is free to deform. Such flows are often further distinguished by the presence of one or more contact lines. The primary focus of research in this thesis is the rigorous computational investigation and the detailed experimental verification of the dynamics of microscale fluid flows with moving contact lines. First, a new method is reported for deflecting a microscopic jet emanating from a nozzle away from the nozzle's axis of symmetry. It relies on putting energy into the jet through an asymmetric heater embedded in the nozzle. Whether the contact line is fixed or free is shown to profoundly impact the extent of jet deflection at a given flow rate. The second problem relates to the use of pin-tools for the deposition of small quantities of liquids on substrates. A convenient setup for studying in a controlled manner the dynamics involved in liquid deposition on a substrate using a pin-tool is the so-called liquid bridge. In this thesis, highly accurate and robust numerical algorithms based on the Galerkin/finite element method (G/FEM) are developed for the prediction of the dynamics of deflecting sheets, breakup of free jets, and liquid bridges with dynamic wetting. Accuracy of the computations are reinforced by comparison of predictions to experimental measurements obtained from high speed digital imaging.




Basaran, Purdue University.

Subject Area

Chemical engineering|Mechanics

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