Temperature-Dependent Property Effects on Laminar Flow Characteristics in a Rectangular Microchannel

2001 ◽  
Author(s):  
Ho Joon Park ◽  
Sang Young Son ◽  
Mun Cheol Choi ◽  
Geunbae Lim ◽  
In-Seob Song ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Laminar Flow ◽  
Flow Resistance ◽  
Flow Characteristics ◽  
Working Fluid ◽  
Micro Channel ◽  
Temperature Dependent ◽  
Micro Piv ◽  
Piv Measurement ◽  
Dependent Property

Abstract This paper investigated experimentally effects of the temperature-dependent property on the laminar flow characteristics in the micro-channel, where water was used as a working fluid. A rectangular straight micro-channel was fabricated with the dimension of 57 μm (H) × 200 μm (W) × 48050 μm (L), in which the resistance temperature detectors (RTDs) were integrated to measure precise temperatures of the fluid directly on the inside-surface of the channel wall. A micro-heater was also installed at the outlet of the channel to generate the heat flux. We measured pressure drop by increasing mass flow rate and the applied heating power. At the same time, micro-Particle Image Velocimetry (micro-PIV) [1] measured the detailed velocity fields along the microchannel, where the wall temperature varied. Based on the pressure drop and Micro-PIV measurement, it was determined that the variation of the fluid property along the microchannel has an effect significantly on flow resistance but not considerably on the velocity profile. Also, it was observed that flow resistance and velocity field shows a good agreement with those estimated in the macro laminar theory under our experimental conditions.

Analysis of Flow Resistance Inside Microchannels With Different Inlet Configurations Using Micro-PIV System

2003 ◽  
Author(s):  
Sang-Joon Lee ◽  
Guk-Bae Kim
Keyword(s):  
Flow Resistance ◽  
Reduction Rate ◽  
Flow Characteristics ◽  
Entrance Region ◽  
Curvature Radius ◽  
Microfluidic Chips ◽  
Mean Velocity ◽  
Dimethyl Siloxane ◽  
Micro Piv ◽  
Macro Scale

Most microfluidic chips consist of several microchannels inside. In order to design microfluidic chips efficiently, it is important to predict the flow passage and to understand the flow characteristics on the chip. In this study, the flow structure inside microchannels has been investigated using a micro-PIV system. We focused on the flow resistance with respect to the inlet configuration of microchannels. The microchannels made of poly-dimethyl-siloxane (PDMS) material were fabricated by a micro-molding technique using SU-8 (photoresist) master. The width (w) and depth of the microchannels were fixed as 100 μm and 58 μm, respectively. Six different inlet configurations with curvature radii in the ranges from r = 0.2w to 1.5w were tested in this study. As a result, with increasing the curvature radius of the inlet corner, the streamwise mean velocity develops slowly in the entrance region, but the fully developed velocity at further downstream is increased. When the curvature radius is larger than r = 0.6w, the reduction rate of flow resistance is not so significant. For the microchannels with r = 0.6w, 0.8w and 1.0w the downstream mean velocity at channel center has nearly the same value of about 276 mm/sec, 10.5% larger than that of r = 0.2w. The simple rounding of microchannel inlet corner reduces flow resistance effectively by smoothing the incoming flow. The length of entrance region is much smaller than that of macro-scale channel.

Micro-PIV Measurement on Transient Flows in Pneumatic MEMS Device for Cell Trapping

2011 ◽  
Author(s):  
Hyun Dong Kim ◽  
Kyung Chun Kim
Keyword(s):  
Flow Characteristics ◽  
Operational Conditions ◽  
Cell Trapping ◽  
Transient Flows ◽  
Micro Piv ◽  
Cell Chip ◽  
Piv Measurement ◽  
Measurement Results ◽  
Equilibrium Region ◽  
Pneumatic Vibrator

This paper presents a micro-PIV measurement for investigation of flow characteristics in a micro chamber for trapping of a live cell. The micro cell chip consisting of pneumatic vibrator arrays and a trap chamber was fabricated through a replica molding technology with a SU-8 mold and Polydimethylsiloxane (PDMS) polymer. The single cell in the trap chamber was manipulated and trapped in the equilibrium region by exploiting the geometrical symmetry of the vibrators. The x-axial velocity of the viscous fluid induced by the deformation of the flexible diaphragms was eliminated or minimized at the center of vibrators. From the measurement results, the proper operational conditions of the vibrators were determined and it is also verified that the particle can be actively manipulated and trapped as desired.

scholarly journals Flow resistance along the rat renal tubule

2018 ◽  
Vol 315 (5) ◽  
pp. F1398-F1405 ◽  
Author(s):  
Gabrielle G. Gilmer ◽  
Venkatesh G. Deshpande ◽  
Chung-Lin Chou ◽  
Mark Knepper
Keyword(s):  
Pressure Drop ◽  
Laminar Flow ◽  
Flow Resistance ◽  
Renal Tubule ◽  
Collecting Duct ◽  
Maximum Pressure ◽  
Luminal Diameter ◽  
Flow Rates ◽  
Axial Pressure Gradient ◽  
Collecting Ducts

The Reynolds number in the renal tubule is extremely low, consistent with laminar flow. Consequently, luminal flow can be described by the Hagen-Poiseuille laminar flow equation. This equation calculates the volumetric flow rate from the axial pressure gradient and flow resistance, which is dependent on the length and diameter of each renal tubule segment. Our goal was to calculate the pressure drop along each segment of the renal tubule and to determine the points of highest resistance. When the Hagen-Poiseuille equation was used for rat superficial nephrons based on known tubule flow rates, lengths, and diameters, it was found that the maximum pressure drop occurred in two segments: the thin descending limbs of Henle and the inner medullary collecting ducts. The high resistance in the thin descending limbs is due to their small diameters. The steep pressure drop observed in the inner medullary collecting ducts is due to the convergent structure of the tubules, which channels flow into fewer and fewer tubules toward the papillary tip. For short-looped nephrons, the calculated glomerular capsular pressure matched measured values, even with the high collecting duct flow rates seen in water diuresis, provided that tubule compliance was taken into account. In long-looped nephrons, the greater length of thin limb segments is likely compensated for by a larger luminal diameter. Simulation of the effect of proximal diuretics, namely acetazolamide or type 2 sodium-glucose transporter inhibitors, predicts a substantial back pressure in Bowman’s capsule, which may contribute to observed decreases in glomerular filtration rate.

Flow Pattern, Void Fraction and Pressure Drop During Adiabatic Two-Phase Gas-Liquid Flow in Vertical Micro-Channel

2012 ◽  
Author(s):  
Sira Saisorn ◽  
Somchai Wongwises
Keyword(s):  
Pressure Drop ◽  
Flow Pattern ◽  
Void Fraction ◽  
Test Section ◽  
Annular Flow ◽  
Fused Silica ◽  
Working Fluid ◽  
Micro Channel ◽  
Two Phase ◽  
Churn Flow

The experimental investigation is performed to study two-phase flow pattern, void fraction and pressure drop characteristics in a vertical micro-channel. The test section is a fused silica tube with a diameter of 0.53 mm and a length of 320 mm. Air and water are used as working fluid which is introduced to the test section in vertical upward direction. The test runs are done at superficial velocities of gas and liquid ranging respectively from 0.375 to 21.187 m/s and 0.004 to 2.436 m/s. Stereozoom microscope mounted together with camera are employed to conduct flow visualization from which slug flow, throat-annular flow, churn flow, annular flow and annular-rivulet flow are observed. Based on image analysis, void fraction data are obtained and found to be linear relationship with volumetric quality. The frictional pressure drop is relatively high when the formation of churn flow is established. Besides, the two-phase frictional multiplier is found to be strongly dependent on both mass flux and flow pattern.

Flow Characteristics of Dilute Polymer Solutions in Micro Tubes

2007 ◽  
Author(s):  
Keizo Watanabe ◽  
Satoshi Ogata ◽  
Munehiko Hirao
Keyword(s):  
Flow Rate ◽  
Polymer Solutions ◽  
Flow Characteristics ◽  
Fused Silica ◽  
Flow Rate Ratio ◽  
Distilled Water ◽  
Number Range ◽  
Micro Piv ◽  
Dilute Polymer Solutions ◽  
Piv Measurement

Pressure drops and velocity profiles for micro tubes were investigated for the laminar flow of distilled water and dilute polymer solutions. The test micro tubes were fused silica capillaries with diameters in the range of 50.2–251.8 μm, and a value of l/d (length/diameter) of about 340. By performing pressure drop measurements, it is shown that the experimental data agree well with the Hagen-Poiseuille equation in the case of Newtonian fluids. On the other hand, the flow rate of dilute polymer solutions increases relative to that of distilled water in the low Reynolds number range. The increased flow rate ratio is a maximum of about 15% in the case of d = 251.8 μm. For the result of the micro PIV measurement, however, there are few differences between the velocity profile of distilled water and the Peo 5 ppm solution.

Characteristics of Drag Reduction by Guar Gum in Spiral Pipes

2012 ◽  
Vol 58 (2) ◽  
Author(s):  
Yanuar N. ◽  
Gunawan I. ◽  
M. Baqi
Keyword(s):  
Pressure Drop ◽  
High Reynolds Number ◽  
Guar Gum ◽  
Flow Characteristics ◽  
Fuel Oil ◽  
Circular Pipe ◽  
Working Fluid ◽  
Power Law Model ◽  
Comparison Analysis ◽  
High Reynolds

On the transport of fluid using pipe, pressure drop is very important aspect because related with energy consumption. Special pipe as spiral pipe is used as a fuel mixing system of fuel oil on ships. It is intended to prevent precipitation and to reduce the pressure drop. The purpose of this research is to investigate the reduction of pressure drop in a spiral pipe with the addition biopolymer (guar gum). Spiral pipe with aspect ratio, P / Di = 4.3, 6.7 and 7.0 are used in this study. Working fluid used guar gum solution of 150 ppm and 300 ppm. Circular pipe with same diameter is used for comparison. Analysis of flow characteristics based on the power law model for non-Newtonian fluid. Experimental was conducted from low to high Reynolds number up to 50,000. The results showed that the effect of biopolymer guar gum solution can reduce drag either on a circular pipe or spiral pipe.

Dimensionless Analysis of Heat Transfer and Flow Resistance on Laminar Flow Recuperator

2008 ◽  
Author(s):  
Chunyu Yin ◽  
Xiaoyong Yang ◽  
Jie Wang
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Flow Resistance ◽  
Similarity Theory ◽  
Installation Space ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Dimensionless Analysis

Recuperator is one of the key components in the helium-turbine cycle coupled with High Temperature Gas cooled Reactor (HTGR). Synthetically considering the heat transfer coefficients, the pressure drop and installation space of recuperator, it is obviously a trend to use compact heat exchanger as recuperator in nuclear power plant. Recuperator recovers heat from the turbine exhaust gas. It promotes the cycle efficiency over entire power range and in all typical modes including start up and shut down modes. The recuperator’s heat transfer coefficients, height, pressure drop have effect on the recuperator’s effectiveness. The main purpose of this paper is to present the law of heat transfer and flow resistance in laminar flow compact exchanger. Based on the similarity theory, the dimensionless parameters of the plate-fin heat exchanger is given in this paper; and then the the dimensionless analysis of the over-all heat transfer coefficient, recuperator’s effectiveness and flow resistance is presented. Furthermore, relationship between the pressure drop and length is also developed.

Numerical Investigation Into the Thermal Performance of Two-Layered Microchannels With Varying Axial Length and Temperature Dependent Fluid Properties

2015 ◽  
Author(s):  
Olayinka O. Adewumi ◽  
Tunde Bello-Ochende ◽  
Josua P. Meyer
Keyword(s):  
Pressure Drop ◽  
Aspect Ratio ◽  
Thermal Performance ◽  
Axial Length ◽  
Solid Substrate ◽  
Working Fluid ◽  
Temperature Dependent ◽  
Fluid Properties ◽  
Channel Aspect Ratio ◽  
Diameter Channel

This study numerically investigates the thermal performance of a two-layered microchannel heat sink with varying axial length, varying solid substrate aspect ratio (ratio of height to width of the silicon solid substrate) but with a fixed total volume constraint and water as the working fluid. The optimal geometry in terms of channel hydraulic diameter, channel aspect ratio and the solid substrate aspect ratio was selected based on the minimised peak temperature on the heated base of the solid substrate with a constant heat load of 100W. The optimal aspect ratio AR of the solid substrate was discovered to be 4 for all pressure drop range considered in this study but the optimal axial length shows a dependence on pressure drop. Results of the effect of varying axial length on surface heat flux, minimised thermal resistance and temperature variation on the heated base of the solid substrate were also presented and discussed.

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.

Flow Characteristics of Nanofluids According to Nanoparticles Shape

2011 ◽  
Vol 110-116 ◽  
pp. 3728-3736
Author(s):  
Kyo Sik Hwang ◽  
Il Kwon Baek ◽  
Hyun Kyo Shin ◽  
Seok Pil Jang
Keyword(s):  
Pressure Drop ◽  
Laminar Flow ◽  
Zeta Potential ◽  
Base Fluid ◽  
Volume Fraction ◽  
Flow Characteristics ◽  
Dispersion Characteristics ◽  
Step Method ◽  
Water Based ◽  
Shape Of Nanoparticles

In this paper, flow characteristics of water-based Al2O3nanofluids according to nanoparticles shape are experimentally investigated in fully developed laminar flow regime. Al2O3nanofluids of 0.3 Vol. % with sphere-, rod-, blade-, platelet-and brick-shaped nanoparticles are manufactured by the two-step method. Nanoparticles shape dispersed in base fluid are also checked using TEM image. Zeta potential and sedimentation are measured to examine suspension and dispersion characteristics of Al2O3nanofluids with nanoparticles of various shapes. Based on the experimental results, it is found that the pressure drop of Al2O3nanofluids strongly depends on the shape of nanoparticles at the fixed volume fraction of 0.3%. We experimentally show that the pressure drop characteristics of Al2O3nanofluids can be explained by both the surface area per unit mass and the size of nanoparticles which are related with the shape of nanoparticles.

Sign in / Sign up

Export Citation Format

Share Document