scholarly journals Experimental and numerical study on capillary flow along deflectors in plate surface tension tanks in microgravity environment

AIP Advances ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 025020
Author(s):  
Shangtong Chen ◽  
Zhiyi Han ◽  
Li Duan ◽  
Qi Kang
Keyword(s):  
Surface Tension ◽  
Capillary Flow ◽  
Numerical Study ◽  
Microgravity Environment ◽  
Plate Surface

Investigation of Three-Dimensional Flow in Microchannels With Patterned Surfaces

2007 ◽  
Author(s):  
Auro Ashish Saha ◽  
Sushanta K. Mitra
Keyword(s):  
Surface Tension ◽  
Flow Instability ◽  
Numerical Study ◽  
Three Dimensional ◽  
Surface Characteristics ◽  
Bottom Wall ◽  
Surface Tension Effect ◽  
Hydrophobic Region ◽  
Side Walls ◽  
Dimensional Simulation

A three-dimensional numerical simulation of flow in patterned microchannel with alternate layers of hydrophilic and hydrophobic surfaces at the bottom wall is studied here. Surface characteristics of the microchannel are accounted by specifying the contact angle and the surface tension of the fluid. Meniscus profiles with varying amplitude and shapes are obtained under the different specified surface conditions. Flow instability increases as the fluid at the bottom wall traverses alternately from hydrophilic region to hydrophobic region. To understand the surface tension effect of the side walls, a two-dimensional numerical study has also been carried out for the microchannel and the results are compared with three-dimensional simulation. The surface tension effect of the side walls enhances the capillary effect for three-dimensional case.

Tracking of Capillary Interface in Microfluidic Channels

2011 ◽  
Author(s):  
Prashant R. Waghmare ◽  
Farhan Ahmad ◽  
David S. Nobes ◽  
Sushanta K. Mitra
Keyword(s):  
Surface Tension ◽  
Flow Regime ◽  
Fluid Transport ◽  
Capillary Flow ◽  
Laser Source ◽  
Working Fluid ◽  
Microfluidic Channels ◽  
Experimental Setup ◽  
Imaging Device ◽  
Air Interface

Capillarity is commonly used for fluid transport in microfluidic devices. The capillary flow can be divided into three different flow regimes: entry regime, Poiseuille regime, and surface tension regime as shown in Fig. 1[1]. Generally, it is anticipated that at the entrance of any narrow confinement, the flow goes through entrance flow regime. For capillary flow, this entrance regime has generally been neglected in the literature. Beyond this entrance regime, the flow attains the fully developed velocity profile across the channel, which is termed as a Poiseuille flow. Moreover, in the capillary flow, the interface is always under traction — due to the capillary forces and hence, a third flow regime needs to be considered behind the interface which is referred as the surface tension regime. These regimes are yet to be experimentally explored and analyzed. An “in-house” developed μ-PIV system is used to quantify the flow field at the liquid/air interface (surface tension regime) in a rectangular glass microchannel of dimension 1.5 mm (width) × 500 μm (depth). The magnitude of velocity and the flow front evolution along the microchannel is calculated utilizing commercially available image processing software. Figure 2 shows the μ-PIV experimental setup used here. The main components of the experimental setup include an imaging device, magnification optics, and a continuous laser source (473 nm) in back illumination mode. The fluorescent particle of 1.9 m in diameter with DI water is used as a working fluid. The concentration of the microparticles is very less which is approximately 1%, therefore the effect of microbead concentration on the wetting properties is considered to be negligible for the present study. Moreover, it is assumed that the surface properties of the particles also do not affect the fluid flow. The capillary flow interface is captured and the corresponding processed images are presented to depict the velocity field at the liquid/air interface. The enlarged view of the microchannel cross section is shown in Fig. 2. The section A-A is the location at which the images are captured for the analysis.

scholarly journals Numerical study of surface tension effects on bubble detachment in a submerged needle

2015 ◽  
Author(s):  
J. Eshraghi ◽  
E. Kosari ◽  
P. Hadikhani ◽  
A. Amini ◽  
M. Ashjaee ◽  
...  
Keyword(s):  
Surface Tension ◽  
Numerical Study ◽  
Bubble Detachment

Numerical Study of Microchamber Filling in Centrifugal Microfluidics

2011 ◽  
Author(s):  
Nick Niedbalski ◽  
Seok-Won Kang ◽  
Debjyoti Banerjee
Keyword(s):  
Surface Tension ◽  
Numerical Model ◽  
Physical Properties ◽  
Thermal Cycle ◽  
Numerical Study ◽  
Method Comparison ◽  
Thermal Conditions ◽  
Microfluidic System ◽  
Working Fluid ◽  
Driving Mechanism

Numerical investigation of the transient, coupled hydrodynamic and thermal behavior of a novel polymerase chain reaction (PCR) centrifugal microfluidic system is presented in this study. The driving mechanism for flow within these devices is modeled as a combination of the capillary forces and rotationally induced pressure gradient working in opposition to viscous forces, which are functions of rotation speed and fluid properties. The physical properties of the working fluid are in turn functions of temperature, some of which can have significant variations over the operating temperature ranges of a PCR thermal cycle. The complex balance of viscous, capillary, and rotationally induced inertial forces are crucial factors in optimizing the design of such devices. Hence, the effects of temperature variation on the filling performance cannot be neglected. A commercial CFD code is utilized to simulate the filling of a microchamber when subjected to thermal conditions typical of a PCR thermal cycle. The numerical model accounts for the temperature dependence of the working fluid’s viscosity and surface tension by simultaneously solving the Navier-Stokes and energy equations. The free surface morphology (position, shape) and total chamber fill fraction as a function of time is predicted by using the volume of fluids (VOF) method. Comparison of the predictions from the temperature dependent numerical model to that which assume said physical properties to be constant, demonstrates the strong effect of the fluid’s viscosity and surface tension on the filling rate for various rotation speeds.

96-Well Plate Surface Tension Measurements for Fast Determination of Drug Solubility

2008 ◽  
Vol 5 (7) ◽  
pp. 471-476 ◽  
Author(s):  
Tiina Heikkila ◽  
Leena Peltonen ◽  
Saila Taskinen ◽  
Timo Laaksonen ◽  
Jouni Hirvonen
Keyword(s):  
Surface Tension ◽  
Drug Solubility ◽  
Plate Surface ◽  
Fast Determination

NUMERICAL STUDY OF PATTERNS AND THEIR EVOLUTION IN FINITE GEOMETRIES

1996 ◽  
Vol 06 (10) ◽  
pp. 1883-1890 ◽  
Author(s):  
J. PONTES ◽  
C.I. CHRISTOV ◽  
M.G. VELARDE
Keyword(s):  
Surface Tension ◽  
Numerical Study ◽  
Surface Tension Gradient ◽  
Thermal Gradients ◽  
Finite Geometries ◽  
Relative Value ◽  
Finite Layer ◽  
Spatio Temporal ◽  
Buoyancy Driven Convection ◽  
Conductive State

Pattern formation in a finite layer of fluid induced either by buoyancy or by a surface-tension gradient is considered. The fluid is confined between poor conducting horizontal boundaries, leading to patterns with a characteristic horizontal scale much larger than the fluid depth. The evolution of the system is studied by numerical integration of the (1+2)D equation introduced by Knobloch [1990]: [Formula: see text] Here µ is the scaled bifurcation parameter, κ=1, and a represents the effects of a heat transfer finite Biot number. The coefficients β, δ and γ do not vanish when the boundary conditions at top and bottom are not identical (β≠0, δ≠0) or when non-Boussinesq effects are taken into account (γ≠0). When the conductive state becomes unstable due to surface-tension inhomogeneities, it is shown that the system evolves towards a stationary pattern of hexagons with up or down flow depending on the relative value of the coefficients β and δ. In the case of buoyancy-driven convection (β=δ≠0), the system displays a tesselation of steady squares. Knobloch’s equation also describes time-dependent patterns at high thermal gradients, including spatio-temporal chaos, due to the non-variational character of the equation.

Numerical Study and Scale Analysis of Inner and Outer Diameters Prediction in Fabrication of Hollow Fiber Membranes for Nerve Regeneration

2008 ◽  
Author(s):  
Jun Yin ◽  
Nicole Coutris ◽  
Yong Huang
Keyword(s):  
Surface Tension ◽  
Hollow Fiber ◽  
Numerical Study ◽  
Hollow Fiber Membrane ◽  
Nerve Repair ◽  
Vof Method ◽  
Fiber Spinning ◽  
Fabrication Process ◽  
Scale Analysis ◽  
And Control

Recently the semi-permeable hollow fiber membrane (HFM) is finding promising applications in promoting axonal outgrowth for nerve repair and regeneration. It is of interest to model the phase inversion-based HFM fabrication process and control the fabricated HFM geometry. The effect of gravity and surface tension which is frequently ignored in general fiber spinning should be carefully addressed in HFM fabrication modeling. Both the volume of fluid (VOF) method and the scale analysis have been applied to appreciate the effect of gravity and surface tension on the HFM geometry profile. The VOF method-based simulation results reveal that both the gravity and/or surface tension significantly reduce the predicted radii/diameters, while the scale analysis reveals that the gravity or surface tension affects the HFM fabrication process dynamics. Both the approaches warrant the need of including the gravity and surface tension in HFM fabrication process modeling.

Numerical Modeling of Radiative and Convective Heat Transfer From an Irradiated Complex Window Assembly

2000 ◽  
Author(s):  
M. Collins ◽  
S. J. Harrison ◽  
P. H. Oosthuizen ◽  
D. Naylor
Keyword(s):  
Heat Transfer ◽  
Radiative Heat ◽  
Numerical Study ◽  
Two Dimensional ◽  
Plate Surface ◽  
The Finite Element Method ◽  
Radiation Model ◽  
Conjugate Conduction ◽  
Plate Distance ◽  
Steady Laminar

Abstract The present numerical study examines the influence of heated, horizontal, and rotateable louvers on the convective and radiative heat transfer from a hot or cold vertical isothermal surface. The system models absorption of solar energy in a Venetian blind adjacent to the indoor surface of a window. Building on previous analyses, a steady, laminar, two-dimensional, conjugate conduction / convection / radiation model of this problem has been developed, and solutions have been obtained using the finite element method. Validation of the model against existing solutions has been undertaken. Results were obtained for two window temperatures (warm and cool compared to ambient), two louver to plate spacings, and three louver angles. The results clearly demonstrate the effect of the model variables on heat transfer from the plate surface. With few exceptions, steady periodicity along the plate was clearly demonstrated. More importantly, increased independence of the results from the louver angle as louver to plate distance increased was demonstrated.

Numerical Study on Impingement of a Droplet upon a Liquid Film

2010 ◽  
Vol 44-47 ◽  
pp. 2499-2503
Author(s):  
Hong Liu ◽  
Mao Zhao Xie ◽  
Su Chun Wang ◽  
Ming Jia
Keyword(s):  
Surface Tension ◽  
Liquid Film ◽  
Stokes Equations ◽  
Numerical Study ◽  
Surface Tension Force ◽  
Surface Force ◽  
Navier Stokes ◽  
Initial Kinetic Energy ◽  
Droplet Impingement ◽  
Fine Grid

This paper reports progress in the numerical simulations of a droplet impingement upon the wall film of the same liquid. The full Navier-Stokes equations are solved in axisymmetric formulation. The surface tension force is modeled by a continuum surface force (CSF) model. An adapting local refinement technique is used to provide the fine grid coupled by the volume-of fluid (VOF) method for tracking the interface between the gas and the droplet and liquid film. Results indicate that the motion behavior of droplet impingement upon the liquid film is dominantly influenced by the initial kinetic energy and the thickness of the film as well as the surface tension and the liquid viscosity.

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