scholarly journals Concentration profiles of ions and particles under hydrodynamic focusing in Y-shaped square microchannel

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Norikazu Sato ◽  
Daisuke Kawashima ◽  
Masahiro Takei
Keyword(s):  
Reynolds Number ◽  
Flow Rate ◽  
Rate Ratio ◽  
Flow Direction ◽  
Ion Concentration ◽  
Flow Rate Ratio ◽  
Hydrodynamic Focusing ◽  
Cross Sectional ◽  
Particle Stream ◽  
Square Microchannel

AbstractThree-dimensional ion and particle concentrations under hydrodynamic focusing in a Y-shaped square microchannel are numerically simulated to clarify the decrease of the ion concentration along the flow direction within the focused particle stream. The simulation model is theoretically governed by the laminar flow and advection–diffusion equations. The governing equations are solved by the finite volume method. The ion and particle concentration distributions at five cross sections after the confluence of the branch channels are analyzed in 30 cases in which the sheath to sample flow rate ratio Qsh/Qsam and the Reynolds number Re are varied as parameters. The results show that the decrease of the cross-sectional average ion concentration along the flow direction within the particle stream $$\overline{c}_{i}$$ c ¯ i is described by the diffusion length during the residence time with a characteristic velocity scale. In addition, the deformation of the particle stream due to inertial effects is described by a scaled Reynolds number that is a function of the flow rate ratio. The simulated particle stream thicknesses are validated by theory and a simple experiment. This paper reveals the relationship between the ion and particle concentrations and the dimensionless parameters for hydrodynamic focusing in the Y-shaped square microchannel under typical conditions.

The Simulation and Experimental Analysis of Hydrodynamic Focusing Effect inside a Rectangular Microchannel

2015 ◽  
Vol 645-646 ◽  
pp. 449-454
Author(s):  
Shuai Jie Feng ◽  
Xin Qun Shi ◽  
Jing Zeng ◽  
Yan Peng ◽  
Mei Liu
Keyword(s):  
Aspect Ratio ◽  
Flow Rate ◽  
Cross Sections ◽  
Experimental Analysis ◽  
Rate Ratio ◽  
Flow Rate Ratio ◽  
Hydrodynamic Focusing ◽  
Rectangular Microchannel ◽  
Focusing Effect ◽  
Simulation Results

This paper models the hydrodynamic focusing performance of a micro-fluidic chip with rectangular cross-sections, and the relationships between the aspect ratio, flow rate ratio of sheath flows to the sample flow, and dimensions and position of the focused sample flow are obtained. The simulation results are consistent with theoretical outcomes. And preliminary experiments were carried out to prove the simulation results.

A Numerical Investigation of the Onset of Flow Separation in Round-Edge Diverging Tees

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Foo Kok ◽  
Roy Myose ◽  
Klaus A. Hoffmann
Keyword(s):  
Reynolds Number ◽  
Flow Rate ◽  
Flow Separation ◽  
Rate Ratio ◽  
Bypass Graft ◽  
Diameter Ratio ◽  
Flow Rate Ratio ◽  
Radius Of Curvature ◽  
Onset Condition ◽  
Recirculation Length

The onset condition of flow separation in diverging tee junctions was investigated numerically. Flow separation and recirculation at the proximal region of a bypass graft can contribute to early phase graft failure in aortocoronary bypass (ACB) surgery. Rounding the inlet edge of the branch reduces the likelihood of flow separation and recirculation. The recirculating zone at the upstream end of the branch is fully eliminated when a threshold value of mass flow rate ratio is reached. The corresponding flow characteristics obtained from diverging tees with a diameter ratio ≤0.2 and a radius of curvature ≤ 0.25 for a Reynolds number ≤ 1817 indicate that an increasing flow rate ratio induces an exponential decrease in the recirculation length. An increase in the diameter ratio and Reynolds number increases both the onset condition of the flow separation and the recirculation length at the upstream end of the branch. However, a decrease in the diameter ratio reduces the onset condition of separation more effectively than a decrease in the radius of curvature at the junction.

Pressure Drop Measurements for Air Flow Through Open-Cell Aluminum Foam

2004 ◽  
Author(s):  
Nihad Dukhan ◽  
Angel Alvarez
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Flow Rate ◽  
Aluminum Foam ◽  
Flow Direction ◽  
The Other ◽  
Turbulent Regime ◽  
Thick Sample ◽  
Open Cell ◽  
Two Samples

Wind-tunnel pressure drop measurements for airflow through two samples of forty-pore-per-inch commercially available open-cell aluminum foam were undertaken. Each sample’s cross-sectional area perpendicular to the flow direction measured 10.16 cm by 24.13 cm. The thickness in the flow direction was 10.16 cm for one sample and 5.08 cm for the other. The flow rate ranged from 0.016 to 0.101 m3/s for the thick sample and from 0.025 to 0.134 m3/s for the other. The data were all in the fully turbulent regime. The pressure drop for both samples increased with increasing flow rate and followed a quadratic behavior. The permeability and the inertia coefficient showed some scatter with average values of 4.6 × 10−8 m2 and 2.9 × 10−8 m2, and 0.086 and 0.066 for the thick and the thin samples, respectively. The friction factor decayed with the Reynolds number and was weakly dependent on the Reynolds number for Reynolds number greater than 35.

Determination of flow rate ratio for plate valve operating in two-phase medium

1989 ◽  
Vol 25 (7) ◽  
pp. 394-396
Author(s):  
V. E. Shcherba ◽  
I. S. Berezin ◽  
S. S. Danilenko ◽  
I. E. Titov ◽  
P. P. Filippov
Keyword(s):  
Flow Rate ◽  
Rate Ratio ◽  
Flow Rate Ratio ◽  
Two Phase ◽  
Plate Valve ◽  
Phase Medium

Effect of the argon/monomer flow-rate ratio on the flowability trend of PECVD-processed micropowder

2017 ◽  
Vol 328 ◽  
pp. 480-487 ◽  
Author(s):  
V.R. Giampietro ◽  
M. Gulas ◽  
P. Rudolf von Rohr
Keyword(s):  
Flow Rate ◽  
Rate Ratio ◽  
Flow Rate Ratio

Effects of Respiration and Gravity on Infradiaphragmatic Venous Flow in Normal and Fontan Patients

Circulation ◽  
2000 ◽  
Vol 102 (suppl_3) ◽  
Author(s):  
Tain-Yen Hsia ◽  
Sachin Khambadkone ◽  
Andrew N. Redington ◽  
Francesco Migliavacca ◽  
John E. Deanfield ◽  
...  
Keyword(s):  
Flow Rate ◽  
Rate Ratio ◽  
Venous Return ◽  
Fontan Circulation ◽  
Flow Rate Ratio ◽  
Venous Flow ◽  
Beneficial Effects ◽  
In Series ◽  
Expiratory Flow ◽  
Fontan Patients

Background —In the Fontan circulation, pulmonary and systemic vascular resistances are in series. The implications of this unique arrangement on infradiaphragmatic venous physiology are poorly understood. Methods and Results —We studied the effects of respiration and gravity on infradiaphragmatic venous flows in 20 normal healthy volunteers (control) and 48 Fontan patients (atriopulmonary connection [APC] n=15, total cavopulmonary connection [TCPC] n=30). Hepatic venous (HV), subhepatic inferior vena caval (IVC), and portal venous (PV) flow rates were measured with Doppler ultrasonography during inspiration and expiration in both the supine and upright positions. The inspiratory-to-expiratory flow rate ratio was calculated to reflect the effect of respiration, and the supine-to-upright flow rate ratio was calculated to assess the effect of gravity. HV flow depended heavily on inspiration in TCPC compared with both control and APC subjects (inspiratory-to-expiratory flow rate ratio 3.4, 1.7, and 1.6, respectively; P <0.0001). Normal PV flow was higher in expiration, but this effect was lost in TCPC and APC patients (inspiratory-to-expiratory flow rate ratio 0.8, 1.0, and 1.1, respectively; P =0.01). The respiratory influence on IVC flow was the same in all groups. Gravity decreased HV flow more in APC than in TCPC patients (supine-to-upright flow rate ratio 3.2 versus 2.1, respectively; P <0.04) but reduced PV flow equally in all groups. Conclusions —Gravity and respiration have important influences on infradiaphragmatic venous return in Fontan patients. Although gravity exerts a significant detrimental effect on lower body venous return, which is more marked in APC than in TCPC patients, the beneficial effects of respiration in TCPC patients are mediated primarily by an increase in HV flow. These effects may have important short- and long-term implications for the hemodynamics of the Fontan circulation.

scholarly journals Numerical and experimental investigation on the depressurization capacity of a new type of depressure-dominated jet mill bit

2020 ◽  
Vol 17 (6) ◽  
pp. 1602-1615
Author(s):  
Xu-Yue Chen ◽  
Tong Cao ◽  
Kai-An Yu ◽  
De-Li Gao ◽  
Jin Yang ◽  
...  
Keyword(s):  
Flow Rate ◽  
Rate Ratio ◽  
Area Ratio ◽  
Low Flow ◽  
Flow Rate Ratio ◽  
Cuttings Transport ◽  
Horizontal Drilling ◽  
Hole Cleaning ◽  
Bottom Hole ◽  
New Type

AbstractEfficient cuttings transport and improving rate of penetration (ROP) are two major challenges in horizontal drilling and extended reach drilling. A type of jet mill bit (JMB) may provide an opportunity to catch the two birds with one stone: not only enhancing cuttings transport efficiency but also improving ROP by depressuring at the bottom hole. In this paper, the JMB is further improved and a new type of depressure-dominated JMB is presented; meanwhile, the depressurization capacity of the depressure-dominated JMB is investigated by numerical simulation and experiment. The numerical study shows that low flow-rate ratio helps to enhance the depressurization capacity of the depressure-dominated JMB; for both depressurization and bottom hole cleaning concern, the flow-rate ratio is suggested to be set at approximately 1:1. With all other parameter values being constant, lower dimensionless nozzle-to-throat-area ratio may result in higher depressurization capacity and better bottom hole cleaning, and the optimal dimensionless nozzle-to-throat-area ratio is at approximately 0.15. Experiments also indicate that reducing the dimensionless flow-rate ratio may help to increase the depressurization capacity of the depressure-dominated JMB. This work provides drilling engineers with a promising tool to improve ROP.

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