Three-Dimensional CFD Model of Pressure Drop in µTAS Devices in a Microchannel

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Damena D. Agonafer ◽  
J. Yeom ◽  
M. A. Shannon
Keyword(s):  
Pressure Drop ◽  
Figure Of Merit ◽  
Flow Resistance ◽  
Three Dimensional ◽  
Design Rule ◽  
Dynamics Model ◽  
Enhance Heat Transfer ◽  
Micro Total Analysis Systems ◽  
Total Analysis ◽  
Adsorption Desorption

Microposts are utilized to enhance heat transfer, adsorption/desorption, and surface chemical reactions. In a previous study [Yeom et al., J. Micromech. Microeng., 19, p. 065025 (2009)], based in part on an experimental study, an analytical expression was developed to predict the pressure drop across a microchannel filled with arrays of posts with the goal of fabricating more efficient micro-total analysis systems (µTAS) devices for a given pumping power. In particular, a key figure of merit for the design of micropost-filled reactors, based on the flow resistance models was reported thus providing engineers with a design rule to develop efficient µTAS devices. The study did not include the effects of the walls bounding the microposts. In this paper, a three-dimensional computational fluid dynamics model is used to include the effects of three-dimensionality brought about by the walls of the µTAS devices that bound the microposted structures. In addition, posts of smaller size that could not be fabricated for the experiments were also included. It is found that the two- and three-dimensional effects depend on values of the aspect ratio and the blockage ratios. The Reynolds number considered in the experiment that ranged from 1 to 10 was extended to 300 to help determine the range of Re for which the FOM model is applicable.

Static Chaos Microfluid Mixers Using Microblock-Induced Alternating Whirl and Microchannel-Induced Lamination

2003 ◽  
Author(s):  
Sunghwan Chang ◽  
Young-Ho Cho
Keyword(s):  
Pressure Drop ◽  
Flow Channel ◽  
Mixing State ◽  
Alternating Direction ◽  
Micro Total Analysis Systems ◽  
Total Analysis ◽  
Visualization Experiments

We characterize two types of noble static chaos microfluid mixers for the applications to Micro Total Analysis Systems (μTAS): an AW-type microfluid mixer, having a series of microblocks along a flow channel for generating alternating direction whirl (AW) flows, and an AWL-type microfluid mixer, coupling the AW-type microfluid mixers with divided microchannels for generating lamination flows between the alternating whirl flows. For generating whirling flow in microchannels, we design rotating block geometry in microchannels. For chaos mixing, we suggest alternating-directional whirling flows in microchannels. AW, AWL-type microfluid mixers are made of PDMS (Polydimethylsiloxane). We quantify mixing state using phenolphthalein visualization experiments and measure pressure drop through microfluid mixers.

Operational Limits of Suspension Flows Through Sudden Contractions

2001 ◽  
Author(s):  
Boris Stoeber ◽  
Eddie Español ◽  
Dorian Liepmann
Keyword(s):  
Three Dimensional ◽  
Small Particles ◽  
Mechanical Problem ◽  
Suspension Flows ◽  
Low Concentrations ◽  
Empirical Relations ◽  
Short Period ◽  
Micro Total Analysis Systems ◽  
Total Analysis ◽  
Small Channels

Abstract In many microfluidic MEMS (Micro Electromechanical Systems) especially in μTAS (micro Total Analysis Systems) suspensions of small particles are transported from relatively large chambers into small channels. The sudden contractions at the entrance to these channels are critical flow regions where high shear occurs in the fluid. Even very small particles at low concentrations have been observed to accumulate in these regions where they clog the channel inlet occasionally after a short period of time. The operational limitations for three-dimensional suspension flows are examined using dimensional analysis. Thus empirical relations based upon experimental results can be established between the parameters involved in this fluid mechanical problem such as shear rate, particle size and concentration, size and number of sudden contractions, and the time scale of clogging.

Numerical Study of Large Diameter Butterfly Valve on Flow Characteristics

2011 ◽  
Vol 236-238 ◽  
pp. 1653-1657 ◽  
Author(s):  
Xiao Dong Wang ◽  
Jing Liang Dong ◽  
Tian Wang
Keyword(s):  
Pressure Drop ◽  
Flow Resistance ◽  
Numerical Study ◽  
Large Diameter ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Numerical Approach ◽  
Resistance Coefficient ◽  
Butterfly Valve ◽  
Dimensional Simulation

A numerical approach was used to investigate the flow characteristics around a butterfly valve with the diameter of 2108 mm by the commercial computational fluid dynamics (CFD) code FLUENT6.3. The simulation was carried out to predict flow field structure, flow resistance coefficient, hydrodynamics torque and so on, when the large diameter butterfly valve operated at various opening degrees. The three-dimensional simulation results shown that there are vortexes presented near valve back region as the opening degree smaller than 40 degree; the flow resistance coefficient reduces rapidly with the increasing of opening degree and the resistance coefficient is quite small as the angle larger than 50 degree; the hydrodynamic torque reduces with the increasing of opening degree and the hydrodynamic torque is smaller than 20% of maximum torque; the torque ratio and the pressure drop ratio are reduce with the increasing of opening degree, the pressure drop ratio reduces rapidly as the opening degree is smaller than 50 degree.

A fabrication technology for three-dimensional micro total analysis systems

2010 ◽  
Vol 20 (4) ◽  
pp. 045013 ◽  
Author(s):  
Phillip Zellner ◽  
Liam Renaghan ◽  
Zaki Hasnain ◽  
Masoud Agah
Keyword(s):  
Three Dimensional ◽  
Fabrication Technology ◽  
Micro Total Analysis Systems ◽  
Total Analysis

scholarly journals Glass based Micro Total Analysis Systems: Materials, Fabrication methods, and Applications

2021 ◽  
pp. 129859
Author(s):  
Tao Tang ◽  
Yapeng Yuan ◽  
Yaxiaer Yalikun ◽  
Yochiroh Hosokawa ◽  
Ming Li ◽  
...  
Keyword(s):  
Micro Total Analysis Systems ◽  
Total Analysis

scholarly journals A Collision Dynamics Model of a Multi-Level Train

2006 ◽  
Author(s):  
Michelle Priante ◽  
David Tyrell ◽  
Benjamin Perlman
Keyword(s):  
Three Dimensional ◽  
Design Parameters ◽  
Collision Dynamics ◽  
Dynamics Model ◽  
Single Level ◽  
High Speeds ◽  
Front End ◽  
Multi Level ◽  
Low Speeds ◽  
Vertical Accelerations

In train collisions, multi-level rail passenger vehicles can deform in modes that are different from the behavior of single level cars. The deformation in single level cars usually occurs at the front end during a collision. In one particular incident, a cab car buckled laterally near the back end of the car. The buckling of the car caused both lateral and vertical accelerations, which led to unanticipated injuries to the occupants. A three-dimensional collision dynamics model of a multi-level passenger train has been developed to study the influence of multi-level design parameters and possible train configuration variations on the reactions of a multi-level car in a collision. This model can run multiple scenarios of a train collision. This paper investigates two hypotheses that could account for the unexpected mode of deformation. The first hypothesis emphasizes the non-symmetric resistance of a multi-level car to longitudinal loads. The structure is irregular since the stairwells, supports for tanks, and draglinks vary from side to side and end to end. Since one side is less strong, that side can crush more during a collision. The second hypothesis uses characteristics that are nearly symmetric on each side. Initial imperfections in train geometry induce eccentric loads on the vehicles. For both hypotheses, the deformation modes depend on the closing speed of the collision. When the characteristics are non-symmetric, and the load is applied in-line, two modes of deformation are seen. At low speeds, the couplers crush, and the cars saw-tooth buckle. At high speeds, the front end of the cab car crushes, and the cars remain in-line. If an offset load is applied, the back stairwell of the first coach car crushes unevenly, and the cars saw-tooth buckle. For the second hypothesis, the characteristics are symmetric. At low speeds, the couplers crush, and the cars remain in-line. At higher speeds, the front end crushes, and the cars remain in-line. If an offset load is applied to a car with symmetric characteristics, the cars will saw-tooth buckle.

scholarly journals Dynamic response analysis for multi-degrees-of-freedom parallel mechanisms with various types of three-dimensional clearance joints

2021 ◽  
Vol 18 (3) ◽  
pp. 172988142110177
Author(s):  
Jia Yonghao ◽  
Chen Xiulong
Keyword(s):  
Dynamic Response ◽  
Multibody Systems ◽  
Parallel Mechanism ◽  
Three Dimensional ◽  
Response Analysis ◽  
Parallel Mechanisms ◽  
Dynamics Model ◽  
Clearance Joints ◽  
Clearance Joint ◽  
Spatial Parallel Mechanism

For spatial multibody systems, the dynamic equations of multibody systems with compound clearance joints have a high level of nonlinearity. The coupling between different types of clearance joints may lead to abundant dynamic behavior. At present, the dynamic response analysis of the spatial parallel mechanism considering the three-dimensional (3D) compound clearance joint has not been reported. This work proposes a modeling method to investigate the influence of the 3D compound clearance joint on the dynamics characteristics of the spatial parallel mechanism. For this purpose, 3D kinematic models of spherical clearance joint and revolute joint with radial and axial clearances are derived. Contact force is described as normal contact and tangential friction and later introduced into the nonlinear dynamics model, which is established by the Lagrange multiplier technique and Jacobian of constraint matrix. The influences of compound clearance joint and initial misalignment of bearing axes on the system are analyzed. Furthermore, validation of dynamics model is evaluated by ADAMS and Newton–Euler method. This work provides an essential theoretical basis for studying the influences of 3D clearance joints on dynamic responses and nonlinear behavior of parallel mechanisms.

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