Numerical simulation of liquid–gas interface formation in long superhydrophobic microchannels with transverse ribs and grooves

Abstract

Superhydrophobic microchannels have evolved recently as an accepted strategy to mitigate the hydrodynamic resistance tendered in micro-constrictions. In this work, hydrodynamics of a hydrophobic microchannel realized by entrapping air in the cavities located between transversely oriented ribs is numerically investigated. An interface formed between the liquid and air/vapor in the confinement facilitates a resistance free slipping surface for the flowing water. The shape of the meniscus is determined by the pressure difference between air and liquid and is classified as convex, flat, and concave depending on the protrusion angle. Several applications require a long hydrophobic channel in which the liquid pressure decreases lengthwise; consequently the interface shape changes as well. In this regard, a mathematical model is proposed to predict the protrusion angle at a specific distance from the inlet of microchannel. This is incorporated in the computational fluid dynamics (CFD) simulations to define the static geometry of the interface which is varying throughout the length of the channel. Moreover, the boundary is treated as a combination of flat no-slip and curved shear-free regions to mimic the ribs and cavities. Further, the evolution of interface morphology is captured using the volume-of-fluid (VOF) scheme by considering a static contact angle at the solid surface to check the validity of the suggested model. Dynamically evolved protrusion angle is measured for various liquid-gas interface pressures and it is observed that the theoretical scaling proposed by Laplace and Young is well obeyed. Though CFD-VOF simulation scheme is an effective tool for predicting the pressure dependent liquid-gas meniscus and concurrent hydrodynamics of the ribbed microchannel, it is resource intensive. The present study demonstrates that the developed model for static boundary may be adopted alternatively to predict the hydrodynamics of a long hydrophobic microchannel by saving computational resources. Keywordshydrophobic microchannel ribbed channel volume-of-fluid simulation liquid-gas interface

[Retracted] Numerical Simulation Method for Microbial Remediation Effect of Nano Heavy Metal Contaminated Soil

“…The objectives of simulating the microbial degradation remediation process with the numerical modeling method include clarifying the spatial and temporal distribution characteristics of the remediated contaminants, quantitatively revealing the amount of contaminant concentration reduction and remediation time by microbial remediation techniques. The problem with the model in the reference [10][11][12][13] is that it cannot consider the selective or competitive degradation of individual pollutants and can only simulate pollutants as a whole, which tends to ignore the influence of some factors on the remediation effect in the remediation process and increases the error of the numerical simulation results. The numerical simulation method in the reference [14][15][16] simplified the redox reactions involving microorganisms, which may lead to some deviations between the simulation results and the reality.…”

CFD-Based Simulation and Analysis of Hydrothermal Aspects in Solar Channel Heat Exchangers with Various Designed Vortex Generators

“…This technique is largely applied in the design of solar heat exchangers (Menasria et al [6], Tan et al [7], Ghritlahre et al [8], Shirvan et al [9] and Baissi et al [10]). The insertion of ribs yields variations in the flow streamlines, modification in the thermal transfer rates, and an augmentation in the turbulence levels, which generates in enhanced thermal exchange (Tarasevich et al [11], Omari et al [12], Gorelov [13], Joseph et al [14] and Kumar et al [15]).…”