scholarly journals Embedded microheating elements in polymeric micro channels for temperature control and fluid flow sensing

2004 ◽  
Vol 109 (3) ◽  
pp. 335 ◽  
Author(s):  
M. Gaitan ◽  
L.E. Locascio
Keyword(s):  
Fluid Flow ◽  
Temperature Control ◽  
Flow Sensing ◽  
Micro Channels

scholarly journals Selective Transport of Airborne Microparticles Through Micro-channels Under Microgravity

2021 ◽  
Vol 33 (1) ◽  
Author(s):  
Monia Makhoul ◽  
Philippe Beltrame
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Bifurcation Analysis ◽  
Metal Particles ◽  
Microgravity Environment ◽  
Ratchet Effect ◽  
Selective Transport ◽  
Microgravity Experiments ◽  
Particle Drift ◽  
Micro Channels

AbstractThis paper analyzes the possibility of obtaining the selective transport of microparticles suspended in air in a microgravity environment through modulated channels without net displacement of air. Using numerical simulation and bifurcation analysis tools, we show the existence of intermittent particle drift under the Stokes assumption of the fluid flow. The particle transport can be selective and the direction of transport is controlled only by the kind of pumping used. The selective transport is interpreted as a deterministic ratchet effect due to spatial variations in the flow and the particle drag. This ratchet phenomenon could be applied to the selective transport of metal particles during the short duration of microgravity experiments.

A Study on the Strength under Pressure of Micro Heat Exchanger

2006 ◽  
Vol 326-328 ◽  
pp. 265-268
Author(s):  
Taek Joon Son ◽  
Young Shin Lee
Keyword(s):  
Stainless Steel ◽  
Fluid Flow ◽  
Heat Exchanger ◽  
Structural Analysis ◽  
Thin Plate ◽  
Thin Plates ◽  
Micro Channel ◽  
Design Guideline ◽  
Micro Heat Exchanger ◽  
Micro Channels

The strength of micro heat exchanger under pressure is studied in this paper. Micro heat exchanger is made with brazing technology. It is constructed of stainless steel thin plates with micro channels and in/out port for fluid flow. Micro channels in thin plates are formed by etching and all parts including thin plates are joined by brazing. The study on the strength under pressure is performed by structural analysis. For structural analysis, one layer of micro heat exchanger body is considered. It is composed of thin plate with micro channel and brazing filler which is used to join thin plates. This paper shows the tendency of stress behavior and gives design guideline of micro heat exchanger.

Numerical Analysis on Flow Characteristics of Anti-Gravity Flow

2011 ◽  
Author(s):  
Yan Li ◽  
Shuchao Zhang ◽  
Ning Mei
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fluid Flow ◽  
Flow Characteristics ◽  
Gravity Flow ◽  
Radius Of Curvature ◽  
Micro Channel ◽  
Subcooled Boiling ◽  
Evaporation Heat ◽  
Micro Channels

Fluid flow phenomena in micro channels received wide attention due to its high heat transfer coefficient. As a new technique in the field of micro channel phase-change heat transfer, anti-gravity flow can drive fluid flow by capillary force and create enhanced evaporation heat transfer conditions by promoting the formation of an extended meniscus in the three-phase contact-line region. Resulting from the circumferential discrepancy of degree of superheat, the radius of curvature of intrinsic meniscus decreases rapidly as liquid rising up, leading to the formation of capillary pressure gradient. With the increase of heat flux, subcooled boiling occurs and micro-bubble appears at the bottom of the fluted tube. Under the action of buoyancy and drag force, the bubble rises along the channel and at the same time grows continually for the presence of superheat until its break. This paper focuses on the numerical study of flow characteristics of anti-gravity flow in the micro channel and the influence of bubble under the subcooled boiling circumstance. The results shows that bubble plays a positive role in the formation of anti-gravity flow and the analytical expressions are presented for the rising velocity of liquid, the contact angle and the curvature of the intrinsic meniscus, which are all influenced by heat flux, superheat temperature and the geometric parameters of the channel.

Effects of Real Surface Roughness on Fluid Flow in Nanochannels

2010 ◽  
Author(s):  
Ali Kharazmi ◽  
Reza Kamali
Keyword(s):  
Molecular Dynamics ◽  
Surface Roughness ◽  
Fluid Flow ◽  
Computer Program ◽  
Md Simulation ◽  
Real Surface ◽  
Micro Channels

In the present study, a computer program based on a molecular dynamics scheme has been developed for simulating fluid flow in nano- and micro-channels with roughness. According to the previous studies of nanochannels flows, surface roughness has a great effect on the rheology of the flow. Therefore a more realistic surface roughness has been developed and its influence on the fluid flow has been investigated using Molecular Dynamics (MD) Simulation.

scholarly journals Direct demonstration of tubular fluid flow sensing by macula densa cells

2010 ◽  
Vol 299 (5) ◽  
pp. F1087-F1093 ◽  
Author(s):  
Arnold Sipos ◽  
Sarah Vargas ◽  
János Peti-Peterdi
Keyword(s):  
Smooth Muscle ◽  
Fluid Flow ◽  
Smooth Muscle Cells ◽  
Flow Rate ◽  
Muscle Cells ◽  
Macula Densa ◽  
Fluid Composition ◽  
Apical Surface ◽  
Fluid Flow Rate ◽  
Flow Sensing

Macula densa (MD) cells in the cortical thick ascending limb (cTAL) detect variations in tubular fluid composition and transmit signals to the afferent arteriole (AA) that control glomerular filtration rate [tubuloglomerular feedback (TGF)]. Increases in tubular salt at the MD that normally parallel elevations in tubular fluid flow rate are well accepted as the trigger of TGF. The present study aimed to test whether MD cells can detect variations in tubular fluid flow rate per se. Calcium imaging of the in vitro microperfused isolated JGA-glomerulus complex dissected from mice was performed using fluo-4 and fluorescence microscopy. Increasing cTAL flow from 2 to 20 nl/min (80 mM [NaCl]) rapidly produced significant elevations in cytosolic Ca2+ concentration ([Ca2+]i) in AA smooth muscle cells [evidenced by changes in fluo-4 intensity (F); F/F0 = 1.45 ± 0.11] and AA vasoconstriction. Complete removal of the cTAL around the MD plaque and application of laminar flow through a perfusion pipette directly to the MD apical surface essentially produced the same results even when low (10 mM) or zero NaCl solutions were used. Acetylated α-tubulin immunohistochemistry identified the presence of primary cilia in mouse MD cells. Under no flow conditions, bending MD cilia directly with a micropipette rapidly caused significant [Ca2+]i elevations in AA smooth muscle cells (fluo-4 F/F0: 1.60 ± 0.12) and vasoconstriction. P2 receptor blockade with suramin significantly reduced the flow-induced TGF, whereas scavenging superoxide with tempol did not. In conclusion, MD cells are equipped with a tubular flow-sensing mechanism that may contribute to MD cell function and TGF.

A review on the analysis and experiment of fluid flow and mixing in micro-channels

2007 ◽  
Vol 21 (3) ◽  
pp. 536-548 ◽  
Author(s):  
Simon Jayaraj ◽  
Sangmo Kang ◽  
Yong Kweon Suh
Keyword(s):  
Fluid Flow ◽  
Micro Channels

Optically driven pumps and flow sensors for microfluidic systems

2008 ◽  
Vol 222 (5) ◽  
pp. 829-837 ◽  
Author(s):  
H Mushfique ◽  
J Leach ◽  
R Di Leonardo ◽  
M J Padgett ◽  
J M Cooper
Keyword(s):  
Fluid Flow ◽  
Optical Tweezers ◽  
Microfluidic Channel ◽  
Optical Traps ◽  
Spin Angular Momentum ◽  
Flow Sensors ◽  
Flow Sensing ◽  
Optically Trapped ◽  
Surrounding Fluid ◽  
Displace Fluid

This paper describes techniques for generating and measuring fluid flow in microfluidic devices. The first technique is for the multi-point measurement of fluid flow in microscopic geometries. The flow sensing method uses an array of optically trapped microprobe sensors to map out the fluid flow. The optical traps are alternately turned on and off such that the probe particles are displaced by the flow of the surrounding fluid and then retrapped. The particles' displacements are monitored by digital video microscopy and directly converted into velocity field values. The second is a method for generating flow within a microfluidic channel using an optically driven pump. The optically driven pump consists of two counter-rotating birefringent vaterite particles trapped within a microfluidic channel and driven using optical tweezers. The transfer of spin angular momentum from a circularly polarized laser beam causes the particles to rotate at up to 10 Hz. The pump is shown to be able to displace fluid in microchannels, with flow rates of up to 200 m−3 s−1 (200 fL s−1). In addition a flow sensing method, based upon the technique mentioned above, is incorporated into the system in order to map the magnitude and direction of fluid flow within the channel.

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