Showing papers by "Srikanth Vedantam published in 2013"
TL;DR: A new method is proposed to impose no-slip or tunable slip boundary condition by controlling the non-central dissipative components in the modified DPD scheme.
40 citations
TL;DR: In this article, the authors developed a function coupled with the publicly available surface energy minimization code Surface Evolver to handle contact angle hysteresis, where the only inputs to the model are the advancing and receding contact angles of the surface.
Abstract: In this paper, we study equilibrium three-dimensional shapes of drops on hysteretic surfaces. We develop a function coupled with the publicly available surface energy minimization code Surface Evolver to handle contact angle hysteresis. The function incorporates a model for the mobility of the triple line into Surface Evolver. The only inputs to the model are the advancing and receding contact angles of the surface. We demonstrate this model’s versatility by studying three problems in which parts of the triple line advance while other parts either recede or remain stationary. The first problem focuses on the three-dimensional shape of a static pendant drop on a vertical surface. We predict the finite drop volume when impending sliding motion is observed. In the second problem, we examine the equilibrium shapes of coalescing sessile drops on hysteretic surfaces. Finally, we study coalescing puddles in which gravity plays a leading role in determining the equilibrium puddle shape along with hysteresis.
18 citations
TL;DR: In this article, the hydrodynamics of a steady nonuniform developing flow between two infinite parallel plates with hydrophilic and hydrophobic surfaces using the dissipative particle dynamics (DPD) are modeled using partial-slip and no-slink boundary conditions, respectively.
Abstract: Dissipative particle dynamics (DPD) is becoming a popular particle-based method to study flow through microchannels due to the ease with which the presence of biological cells or DNA chains can be modeled. Many lab-on-a-chip devices require the ability to manipulate the transport of cells or DNA chains in the fluid flow. Microchannel surfaces coated with combinations of hydrophilic and hydrophobic materials have been found useful for this purpose. In this work we study numerically the hydrodynamics of a steady nonuniform developing flow between two infinite parallel plates with hydrophilic and hydrophobic surfaces using the DPD. The hydrophobic and hydrophilic surfaces are modeled using partial-slip and no-slip boundary conditions, respectively, in the simulations. We also propose a method to model the inflow and outflow boundaries for the DPD simulations. The simulation results of the developing flow are in good agreement with analytical solutions from continuum theory for no-slip and partial-slip surfaces. The entrance region constitutes a considerable fraction of the channel length in miniaturized devices. Thus it is desirable for the length of the developing region to be short as most microfluidic devices such as cell or DNA separators and mixers are designed for the developed flow field. We study the effect of a hydrophilic strip near the inlet of a hydrophobic microchannel on the developing length. We find that the presence of the hydrophilic strip significantly reduces the developing length.
15 citations