Electrohydrodynamics (EHD) has been a major area of research interest for many decades, where an applied electric ﬁeld can be used to change the behavior of various hydrodynamic phenomena. One interesting problem has been the deformation and breakup of liquid droplets under applied electric ﬁelds. In this study, we look at the effect of an applied electric ﬁeld on the behavior of sessile and impacting drops using numerical and analytical approaches.
In the ﬁrst part of the thesis, we numerically model the deformation of a sessile drop under an applied electric ﬁeld using Computational Fluid Dynamics (CFD) techniques. A volume of ﬂuid (VOF) approach is used to implement a 2D axisymmetric multiphase model of a sessile drop in the software package STARCCM+. Results are presented showing both the steady and unsteady deformation of the droplet at different applied voltages. A perceptible deformation of the drop is observed, with unsteady motion of the liquid-vapor interface shedding light on the mechanics of the process.
In the second part of the thesis, an analytical model is formulated to explain the results of a drop impact experiment conducted in the presence of an applied electric ﬁled. The experiments indicate that the rebound height of the drop increases with magnitude of electric ﬁeld, culminating in a necking and drop separation event at a large enough electric ﬁeld. Analytical expressions for the different forces acting on the impacting drop are developed, namely the gravity, capillary, momentum, and electrostatic forces. An analysis of these forces indicates that the necking and separation of the impacting drop occurs when the upwards electrostatic and momentum forces exceed the downward gravity and capillary forces. The results obtained from the studies performed in this thesis will enable a better understanding of the physics and promote the application of electric ﬁelds in practical engineering applications such as boiling, condensation, deicing, electronics thermal management.
|Advisor:||Dhillon, Navdeep Singh|
|Commitee:||Toossi, Reza, Kalman, Joseph, Moghtadernejad, Sara|
|School:||California State University, Long Beach|
|Department:||Mechanical and Aerospace Engineering|
|School Location:||United States -- California|
|Source:||MAI 81/8(E), Masters Abstracts International|
|Keywords:||Sessile, Impacting drops|
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