Showing papers by "Mahesh V. Panchagnula published in 2014"
TL;DR: The shape of a drop on an inclined hysteretic surface has been studied both theoretically and experimentally in this article, where the energy minimization method from SE is coupled with a triple line dynamics model to incorporate contact angle hysteresis (CAH) into the simulations.
33 citations
TL;DR: The principal modeling challenges posed by sprays are reviewed, and the capabilities of different modeling approaches are discussed by classifying them according to the basis for their statistical representation and the level of closure.
Abstract: The characteristic features of sprays pose unique challenges to multiphase flow methods that are used to model and simulate their behavior. This article reviews the principal modeling challenges posed by sprays, and discusses the capabilities of different modeling approaches by classifying them according to the basis for their statistical representation and the level of closure. The article goes on to provide guidelines for their comparative assessment and also a perspective on the outlook for spray modeling. Multiphase flow simulation approaches that are used for spray computations are classified according to scale, accuracy, computational cost and problem complexity. The requirements of a simulation method to be successfully used for spray computation are then discussed. The review concludes with a perspective on the outlook for spray simulation methods.
18 citations
TL;DR: In this paper, the shape of the triple line during these pinning/de-pinning events on various chemically heterogeneous surfaces was captured using an experimental and a computational technique, and the experimental setup lies in its ability to capture the microscopic triple line shape and its evolution in addition to measuring the local contact angles.
4 citations
Posted Content•
TL;DR: The dynamics and stability of a fluid-filled hollow cylindrical shell rolling on an inclined plane are analyzed in this paper, where the authors show that the terminal state is associated with a constant acceleration.
Abstract: The dynamics and stability of a fluid-filled hollow cylindrical shell rolling on an inclined plane are analyzed. We study the motion in two dimensions by analyzing the interaction between the fluid and the cylindrical shell. An analytical solution is presented to describe the unsteady fluid velocity field as well as the cylindrical shell motion. From this solution, we show that the terminal state is associated with a constant acceleration. We also show that this state is independent of the liquid viscosity and only depends on the ratio of the shell mass to the fluid mass. We then analyze the stability of this unsteady flow field by employing a quasi-steady frozen-time framework. The stability of the instantaneous flow field is studied and transition from a stable to an unstable state is characterized by the noting the time when the eigenvalue crosses the imaginary axis. It is observed that the flow becomes unstable due to long wavelength axial waves. We find a critical Reynolds number ($\approx 5.6$) based on the shell angular velocity at neutral stability with the corresponding Taylor number being $\approx 125.4$. Remarkably, we find that this critical value is independent of the dimensionless groups governing the problem. We show that this value of the critical Reynolds number can be explained from a comparison of time scales of motion and momentum diffusion, which predicts a value near $2 \pi$.
3 citations
15 Dec 2014
TL;DR: In this paper, a 1D plug flow evaporator has been considered to study the evaporation, atomization and transport of polydisperse droplets in a pulsating air stream.
Abstract: In the present work a 1D plug flow evaporator has been considered to study the evaporation, atomization and transport of polydisperse droplets in a pulsating air stream. The pulsation in the air flow is very common in the real combustor due to the thermo acoustic instabilities. Population balance modeling approach is used to study the continuous evaporation and atomization process. An Eulerian-Eulerian multiphase framework is used to capture the polydispersity of the system. For the evaporation the fixed drop size methodology of the D2 law has been used whereas, for the atomization the conservation of mass has been considered during the breakage. The objective of this work is to study the pulsation frequency on the dispersion of droplets without and with presence of the evaporation and atomization rate. From the results, clustering of particles in different locations has been identified. The variation of Sauter Mean Diameter (SMD) is presented and the non-linear behaviour has been identified in the process.Copyright © 2014 by ASME
1 citations
1 citations