Modeling and Experimental Characterization of Pressure Drop in Gravity-Driven Microfluidic Systems

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
Antti-Juhana Mäki ◽  
Samu Hemmilä ◽  
Juha Hirvonen ◽  
Nathaniel Narra Girish ◽  
Joose Kreutzer ◽  
...  
Keyword(s):  
Microfluidic Systems ◽  
Flow Rates ◽  
Driven Systems ◽  
Pumping System ◽  
Proposed Model ◽  
Gravity Driven ◽  
Passive Pumping ◽  
Gravity Driven Flow ◽  
Real Flow

Passive pumping using gravity-driven flow is a fascinating approach for microfluidic systems. When designing a passive pumping system, generated flow rates should be known precisely. While reported models used to estimate the flow rates do not usually consider capillary forces, this paper shows that their exclusion is unrealistic in typical gravity-driven systems. Therefore, we propose a new analytical model to estimate the generated flow rates. An extensive set of measurements is used to verify that the proposed model provides a remarkably more precise approximation of the real flow rates compared to the previous models. It is suggested that the developed model should be used when designing a gravity-driven pumping system.

Steady inclined flows of granular-fluid mixtures

2009 ◽  
Vol 641 ◽  
pp. 359-387 ◽  
Author(s):  
D. BERZI ◽  
J. T. JENKINS
Keyword(s):  
Volume Flow ◽  
Angle Of Repose ◽  
Recent Theory ◽  
Fluid Mixture ◽  
Flow Rates ◽  
Fluid Mixtures ◽  
Gravity Driven ◽  
Granular Fluid ◽  
Gravity Driven Flow ◽  
Inclined Flow

We extend a recent theory for steady uniform gravity-driven flow of a highly concentrated granular-fluid mixture over an erodible bed between frictional sidewalls. We first include angles of inclination greater than the angle of repose of the particles; then, we introduce a boundary condition for flow over a rigid bumpy bed. We compare the predictions of the resulting theory with the volume flow rates, depths and angles of inclination measured in the experiments on dry and variously saturated flows over rigid and erodible boundaries. Finally, we employ the resulting theory, with the assumption that the flow is shallow, to solve, in an approximate way, for the variation of height and average velocities along a steady non-uniform inclined flow of a granular-fluid mixture that moves over a rigid bumpy bed. The solutions exhibit features of the flow seen in the experiments – for example, a dry bulbous snout in advance of the fluid, whose length increases with increasing number of the particles and that disappears with increasing velocity – for which satisfactory explanations were lacking.

A Modified Beavers and Joseph Condition for Gravity-Driven Flow over Porous Layers

2021 ◽  
Vol 16 ◽  
pp. 79-94
Author(s):  
M.S. Abu Zaytoon ◽  
Roberto Silva-Zea ◽  
M. H. Hamdan
Keyword(s):  
Porous Layer ◽  
Velocity Shear ◽  
Slip Parameter ◽  
Interfacial Velocity ◽  
Flow Rates ◽  
Porous Layers ◽  
Inclined Channel ◽  
Gravity Driven ◽  
Flow Through ◽  
Gravity Driven Flow

Gravity-driven flow through an inclined channel over a semi-infinite porous layer is considered in order to obtain a modification to the usual Beavers and Joseph slip condition that is suitable for this type of flow. Expressions for the velocity, shear stress, volumetric flow rates, and pressure distribution across the channel are obtained together with an expression for the interfacial velocity. In the absence of values for the slip parameter when the flow is over a Forchheimer porous layer, this work provides a relationship between the slip parameters of the Darcy and Forchheimer layers. Expressions for the interfacial velocities in both cases are obtained. This original work is intended to provide baseline analysis and a benchmark with which more sophisticated types of flow, over porous layers in an inclined domain can be compared.

The Design and Analysis of Piezoelectrically Actuated Microfluidic Systems

2003 ◽  
Author(s):  
Paul Chiarot ◽  
Pierre Sullivan ◽  
Ridha Ben Mrad
Keyword(s):  
Flow Characteristics ◽  
Secondary Flows ◽  
Design Tools ◽  
Microfluidic Systems ◽  
Element Analysis ◽  
Flow Rates ◽  
Mixing Chamber ◽  
Fundamental Understanding ◽  
Passive Mixing

Microfluidics requires a fundamental understanding of flow characteristics on the microscale. This work combines the design and characterization of passive microfluidic components. The goal is to improve the design and reliability of these devices and to develop and confirm design tools for microfluidic systems. To predict operating performance, models are developed for various components including two designs of a passive conduit valve and a passive mixing chamber. These are examined at different geometric scales and conditions using Finite Element Analysis (FEA) to determine the dimensional effect on the available flow rates, secondary flows, and driving pressures. FEA predicts the characteristics of the microfluidic devices including diodicity and achievable flow rates.

EFFECT OF FLOCCULATING AGENTS ON DRAG IN GRAVITY-DRIVEN FLOW SYSTEMS

2017 ◽  
Vol 44 (4) ◽  
pp. 339-347
Author(s):  
M. K. S. V. Raghav ◽  
Ravi Teja ◽  
Chirravuri Subbarao
Keyword(s):  
Flow Systems ◽  
Gravity Driven ◽  
Gravity Driven Flow

Drag reduction using mixed solutions of hydrotrope and surfactant in gravity driven flow systems

2013 ◽  
Vol 8 (3) ◽  
pp. 22-27
Author(s):  
M. Venkata Ramana ◽  
◽  
Ch. V. Subbarao ◽  
P. V. Gopal singh ◽  
Krishna Prasad K.M.M ◽  
...  
Keyword(s):  
Drag Reduction ◽  
Mixed Solutions ◽  
Flow Systems ◽  
Gravity Driven ◽  
Gravity Driven Flow

scholarly journals Computation of transient flow rates in passive pumping micro-fluidic systems

Lab on a Chip ◽  
2009 ◽  
Vol 9 (1) ◽  
pp. 107-114 ◽  
Author(s):  
I-Jane Chen ◽  
Eugene C. Eckstein ◽  
Ernő Lindner
Keyword(s):  
Transient Flow ◽  
Flow Rates ◽  
Passive Pumping

Numerical Multiphysics Modeling of Microdroplet Motion Dynamics in Digital Microfluidic Systems

2010 ◽  
Author(s):  
Ali Ahmadi ◽  
Jonathan F. Holzman ◽  
Homayoun Najjaran ◽  
Mina Hoorfar
Keyword(s):  
Numerical Algorithm ◽  
Moving Boundary ◽  
Microfluidic Systems ◽  
Multiphysics Modeling ◽  
Transient Motion ◽  
Proposed Model ◽  
Digital Microfluidic ◽  
Motion Dynamics

In this paper a novel numerical algorithm is proposed for modeling the transient motion of microdroplets in digital microfluidic systems. The new methodology combines the effects of the electrostatic and hydrodynamic pressures to calculate the actuating and opposing forces and the moving boundary of the microdroplet. The proposed model successfully predicts transient motion of the microdroplet in digital microfluidic systems, which is crucial in the design, control and fabrication of such devices. The results of such an analysis are in agreement with the expected trend.

scholarly journals Two-Dimensional Convection Induced by Gravity and Centrifugal Forces in a Rotating Porous Layer Far Away from the Axis of Rotation

1998 ◽  
Vol 4 (2) ◽  
pp. 73-90 ◽  
Author(s):  
Peter Vadasz ◽  
Saneshan Govender
Keyword(s):  
Rayleigh Number ◽  
Porous Layer ◽  
Temperature Fields ◽  
Wave Number ◽  
Marginal Stability ◽  
Two Dimensional ◽  
Wide Range ◽  
Gravity Driven ◽  
Gravity Driven Flow ◽  
The Stability

The stability and onset of two-dimensional convection in a rotating fluid saturated porous layer subject to gravity and centrifugal body forces is investigated analytically. The problem corresponding to a layer placed far away from the centre of rotation was identified as a distinct case and therefore justifying special attention. The stability of a basic gravity driven convection is analysed. The marginal stability criterion is established in terms of a critical centrifugal Rayleigh number and a critical wave number for different values of the gravity related Rayleigh number. For any given value of the gravity related Rayleigh number there is a transitional value of the wave number, beyond which the basic gravity driven flow is stable. The results provide the stability map for a wide range of values of the gravity related Rayleigh number, as well as the corresponding flow and temperature fields.

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