Enhancing the capture efficiency and homogeneity of single-layer flow-through trapping microfluidic devices using oblique hydrodynamic streams

The analysis of two-layer exchange flow through contractions with a barotropic component treated by Armi & Farmer (1986) is extended to include exchange flows over sills and through a combination of a sill and contraction. It is shown that exchange over a sill is fundamentally different from exchange through a contraction. Control at the sill crest acts primarily through the deeper layer into which the sill projects and only indirectly controls the surface layer. This asymmetry in the control results in asymmetrical flows. The interface depth above the crest is not one half the total depth, as assumed in other studies by analogy with flow through contractions, but is somewhat deeper; the maximal exchange rate is less than for flow through a contraction of equal depth. When both a sill and a contraction are present, the contraction influences control at the sill crest only if it lies between the sill and the source of denser water. The response to barotropic flow is also asymmetrical: the transition to single-layer flow occurs at much lower speeds for a barotropic component in one direction than the other.Results of the analysis are applied to exchange flow through the Strait of Gibraltar, which includes both a sill and a contraction. It is shown that maximal exchange conditions apply throughout part of the tidal cycle, and observations illustrate several of the analytical predictions for barotropic flows, including the formation of fronts, single-layer flow, submaximal exchange and reverse flow.

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Shear-augmented solute dispersion during drug delivery for three-layer flow through microvessel under stress jump and momentum slip-Darcy model

Applied Mathematics and Mechanics ◽

10.1007/s10483-021-2737-8 ◽

2021 ◽

Author(s):

G. Bashaga ◽

S. Shaw

Keyword(s):

Drug Delivery ◽

Stress Jump ◽

Darcy Model ◽

Solute Dispersion ◽

Flow Through ◽

Layer Flow

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Transcritical two-layer flow over topography

Journal of Fluid Mechanics ◽

10.1017/s0022112087001101 ◽

1987 ◽

Vol 178 ◽

pp. 31-52 ◽

Cited By ~ 97

Author(s):

W. K. Melville ◽

Karl R. Helfrich

Keyword(s):

Steady Flow ◽

Solitary Waves ◽

Numerical Solutions ◽

Kdv Equation ◽

Single Layer ◽

Cubic Nonlinearity ◽

Arbitrary Length ◽

Weakly Nonlinear ◽

Flow Over Topography ◽

Layer Flow

The evolution of weakly-nonlinear two-layer flow over topography is considered. The governing equations are formulated to consider the effects of quadratic and cubic nonlinearity in the transcritical regime of the internal mode. In the absence of cubic nonlinearity an inhomogeneous Korteweg-de Vries equation describes the interfacial displacement. Numerical solutions of this equation exhibit undular bores or sequences of Boussinesq solitary waves upstream in a transcritical regime. For sufficiently large supercritical Froude numbers, a locally steady flow is attained over the topography. In that regime in which both quadratic and cubic nonlinearity are comparable, the evolution of the interface is described by an inhomogeneous extended Kortewegde Vries (EKdV) equation. This equation displays undular bores upstream in a subcritical regime, but monotonic bores in a transcritical regime. The monotonic bores are solitary wave solutions of the corresponding homogeneous EKdV equation. Again, locally steady flow is attained for sufficiently large supercritical Froude numbers. The predictions of the numerical solutions are compared with laboratory experiments which show good agreement with the solutions of the forced EKdV equation for some range of parameters. It is shown that a recent result of Miles (1986), which predicts an unsteady transcritical regime for single-layer flows, may readily be extended to two-layer flows (described by the forced KdV equation) and is in agreement with the results presented here.Numerical experiments exploiting the symmetry of the homogeneous EKdV equation show that solitary waves of fixed amplitude but arbitrary length may be generated in systems described by the inhomogeneous EKdV equation.

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Large-eddy simulation of atmospheric boundary layer flow through wind turbines and wind farms

Journal of Wind Engineering and Industrial Aerodynamics ◽

10.1016/j.jweia.2011.01.011 ◽

2011 ◽

Vol 99 (4) ◽

pp. 154-168 ◽

Cited By ~ 282

Author(s):

Fernando Porté-Agel ◽

Yu-Ting Wu ◽

Hao Lu ◽

Robert J. Conzemius

Keyword(s):

Boundary Layer ◽

Large Eddy Simulation ◽

Atmospheric Boundary Layer ◽

Wind Turbines ◽

Boundary Layer Flow ◽

Wind Farms ◽

Eddy Simulation ◽

Large Eddy ◽

Flow Through ◽

Layer Flow

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Vanadium microfluidic fuel cell with novel multi-layer flow-through porous electrodes: Model, simulations and experiments

Applied Energy ◽

10.1016/j.apenergy.2016.05.072 ◽

2016 ◽

Vol 177 ◽

pp. 729-739 ◽

Cited By ~ 26

Author(s):

Li Li ◽

Georgios Nikiforidis ◽

Michael K.H. Leung ◽

Walid A. Daoud

Keyword(s):

Fuel Cell ◽

Porous Electrodes ◽

Model Simulations ◽

Flow Through ◽

Microfluidic Fuel Cell ◽

Layer Flow

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The stability of boundary-layer flow over single-and multi-layer viscoelastic walls

Journal of Fluid Mechanics ◽

10.1017/s0022112088002745 ◽

1988 ◽

Vol 196 ◽

pp. 359-408 ◽

Cited By ~ 48

Author(s):

K. S. Yeo

Keyword(s):

Boundary Layer ◽

Boundary Layer Flow ◽

Single Layer ◽

Viscous Sublayer ◽

Rigid Base ◽

Theoretical Treatment ◽

Dynamical Condition ◽

Compliant Walls ◽

Layer Flow ◽

The Stability

In this paper, we are concerned with the linear stability of zero pressure-gradient laminar boundary-layer flow over compliant walls which are composed of one or more layers of isotropic viscoelastic materials and backed by a rigid base. Wall compliance supports a whole host of new instabilities in addition to the Tollmien-Schlichting mode of instability, which originally exists even when the wall is rigid. The perturbations in the flow and the compliant wall are coupled at their common interface through the kinematic condition of velocity continuity and the dynamical condition of stress continuity. The disturbance modes in the flow are governed by the Orr-Sommerfeld equation using the locally-parallel flow assumption, and the response of the compliant layers is described using a displacement-stress formalism. The theoretical treatment provides a unified formulation of the stability eigenvalue problem that is applicable to compliant walls having any finite number of uniform layers; inclusive of viscous sublayer. The formulation is well suited to systematic numerical implementation. Results for single- and multi-layer walls are presented. Analyses of the eigenfunctions give an insight into some of the physics involved. Multi-layering gives a measure of control over the stability characteristics of compliant walls not available to single-layer walls. The present study provides evidence which suggests that substantial suppression of disturbance growth may be possible for suitably tailored compliant walls.

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Rheology and microstructural evolution in pressure-driven flow of a magnetorheological fluid with strong particle–wall interactions

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x11429601 ◽

2012 ◽

Vol 23 (9) ◽

pp. 969-978 ◽

Cited By ~ 4

Author(s):

Murat Ocalan ◽

Gareth H. McKinley

Keyword(s):

Microfluidic Devices ◽

Magnetorheological Fluid ◽

Time Dependent ◽

Mr Fluid ◽

Flow Through ◽

Fluid Particles ◽

And Performance ◽

Pressure Driven Flow ◽

Actuator Design ◽

Pressure Driven

The interaction between magnetorheological (MR) fluid particles and the walls of the device that retain the field-responsive fluid is critical as this interaction provides the means for coupling the physical device to the field-controllable properties of the fluid. This interaction is often enhanced in actuators by the use of ferromagnetic walls that generate an attractive force on the particles in the field-on state. In this article, the aggregation dynamics of MR fluid particles and the evolution of the microstructure in pressure-driven flow through ferromagnetic channels are studied using custom-fabricated microfluidic devices with ferromagnetic sidewalls. The aggregation of the particles and the time-dependent evolution in the microstructure is studied in rectilinear, expansion and contraction channel geometries. These observations help identify methods for improving MR actuator design and performance.

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