A New Flow Control Technique for Handling Infinitesimal Flows Inside a Lab-On-a-Chip

2006 ◽  
Vol 30 (2) ◽  
pp. 110-116
Author(s):  
Su-Dong Han ◽  
Guk-Bae Kim ◽  
Sang-Joon Lee
Keyword(s):  
Flow Control ◽  
Lab On A Chip ◽  
Control Technique

scholarly journals Model-Based Analysis of Flow Separation Control in a Curved Diffuser by a Vibration Wall

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1781
Author(s):  
Weiyu Lu ◽  
Xin Fu ◽  
Jinchun Wang ◽  
Yuanchi Zou
Keyword(s):  
Flow Field ◽  
Flow Control ◽  
Flow Separation ◽  
Vibration Frequency ◽  
Flow Instability ◽  
Control Technique ◽  
Simplified Model ◽  
Main Stream ◽  
Control Performance ◽  
Flow Separation Control

Vibration wall control is an important active flow control technique studied by many researchers. Although current researches have shown that the control performance is greatly affected by the frequency and amplitude of the vibration wall, the mechanism hiding behind the phenomena is still not clear, due to the complex interaction between the vibration wall and flow separation. To reveal the control mechanism of vibration walls, we propose a simplified model to help us understand the interaction between the forced excitation (from the vibration wall) and self-excitation (from flow instability). The simplified model can explain vibration wall flow control behaviors obtained by numerical simulation, which show that the control performance will be optimized at a certain reduced vibration frequency or amplitude. Also, it is shown by the analysis of maximal Lyapunov exponents that the vibration wall is able to change the flow field from a disordered one into an ordered one. Consistent with these phenomena and bringing more physical insight, the simplified model implies that the tuned vibration frequency and amplitude will lock in the unsteady flow separation, promote momentum transfer from the main stream to the separation zone, and make the flow field more orderly and less chaotic, resulting in a reduction of flow loss.

Fabrication and testing of hydrogel-based microvalves for flow control in flexible lab-on-a-chip systems

2012 ◽  
Author(s):  
Ang Li ◽  
Jonathan Lee ◽  
Bonnie L. Gray ◽  
Paul C. H. Li
Keyword(s):  
Flow Control ◽  
Lab On A Chip

Gas Flow Control Employing Temperature and Pressure Compensation

1971 ◽  
Vol 93 (3) ◽  
pp. 200-205
Author(s):  
Seth R. Goldstein ◽  
Andrew C. Harvey
Keyword(s):  
Flow Control ◽  
Gas Flow ◽  
Absolute Temperature ◽  
Control Technique ◽  
Order Error ◽  
Upstream Pressure ◽  
Nonlinear Temperature ◽  
High Pressure Oxygen ◽  
Trapped Gas ◽  
Pressure Compensation

Two passive gas flow controllers are presented which provide compensation for variations in ambient temperature and supply pressure. One technique, which provides first-order error compensation, utilizes a choked orifice having its area linearily varied in proportion to a diaphragm deflection. Compensation is achieved by applying upstream pressure to one side of the diaphragm, and by applying a trapped gas pressure proportional to absolute temperature on the other side of the diaphragm. General design relationships are presented, and a prototype unit constructed to control a minute flow rate of high-pressure oxygen is described. A second flow control technique is presented which provides the required nonlinear temperature compensation for flow supplied through a constant-area choked orifice. This is achieved by utilizing a compliant volume of trapped gas to generate a pressure proportional to the square root of absolute temperature. This pressure is used to control the pressure upstream of the choked orifice, thus providing constant flow.

FLOW CONTROL AND MECHANISM FOR SLENDER BODY AT HIGH ANGLE OF ATTACK

2005 ◽  
Vol 19 (28n29) ◽  
pp. 1571-1574 ◽  
Author(s):  
XIAO MING ◽  
YUNSONG GU
Keyword(s):  
Flow Control ◽  
High Frequency ◽  
Angle Of Attack ◽  
Control Technique ◽  
High Angle ◽  
Dynamic Measurements ◽  
Wind Tunnel Experiments ◽  
Rolling Angle ◽  
High Angle Of Attack ◽  
Side Force

The wind tunnel experiments for high angle of attack aerodynamics were designed from the inspiration of understanding the mechanism and development of an innovative flow control technique. The side force, varying with the different rolling angle, is featured by bi-stable situation, and can be easily switched by a tiny disturbance. A miniature strake is attached to the nose tip of the model. When the strake is stationary, the direction of the side force can be controlled. When the nose tip strake, as an unsteady control means, is swung the flow pattern could be controlled. The results obtained from dynamic measurements of section side force indicate that when the strake swing at lower frequency the side force can follow the cadence of the swinging strake. With increasing frequency, the magnitude of the side force decreases. At still high frequency, the side force diminishes to zero. The side forces could be also changed proportionally. Based on the experimental factors, the mechanism of the asymmetry is discussed.

Republished: Multiplug flow control technique as a novel transarterial curative approach for the endovascular treatment of cerebrovascular malformations

2021 ◽  
pp. neurintsurg-2021-017418.rep
Author(s):  
H Saruhan Cekirge ◽  
Isil Saatci
Keyword(s):  
Flow Control ◽  
Dural Arteriovenous Fistula ◽  
Vascular Malformations ◽  
The Other ◽  
Control Technique ◽  
Injection Time ◽  
Complete Occlusion ◽  
Transarterial Embolisation ◽  
Embolic Agents ◽  
Liquid Embolic

Herein, we describe the use of a novel multiplug flow control technique for the curative transarterial embolisation of cerebrovascular malformations using liquid embolic agents (LEAs). The idea behind the use of this technique is to substantially control or arrest flow during LEA injection, with multiple plugs simultaneously formed from microcatheters that are placed within all or multiple feeders, so that the penetration of LEAs is facilitated, with flow control decreasing the washout of a malformation. This technique enables the complete occlusion of a vascular malformation in a shorter injection time than that in other methods because penetration is achieved faster. Details of this technique have been described in the treatment of two cases: one case of unruptured temporal arteriovenous malformation and in the other with a falcotentorial dural arteriovenous fistula, in which the vascular malformations were successfully occluded with transarterial embolisation.

Heat Meter Calibration Device of Flow Control Based on Self-Learning Double-Controller

2013 ◽  
Vol 391 ◽  
pp. 588-591
Author(s):  
Yu Sen Li ◽  
Deng Chao Feng
Keyword(s):  
Flow Control ◽  
Control Algorithm ◽  
Current Flow ◽  
Control Flow ◽  
Control Technique ◽  
System Control ◽  
Heat Meter ◽  
Control Precision ◽  
Calibration Device ◽  
Self Learning

This paper use automatic flow control and select advanced flow control technique with intelligent flow control algorithm. It implements full automatic control of the flow, in the process of verification, only need to set the current flow point and start the system, it will control flow automatically. The control curves meet control requirements, and improve system control precision.

Simple frigate shape plasma flow control

2016 ◽  
Vol 230 (14) ◽  
pp. 2693-2699 ◽  
Author(s):  
R Bardera-Mora ◽  
A Conesa ◽  
I Lozano
Keyword(s):  
Flow Control ◽  
Active Flow Control ◽  
Plasma Actuators ◽  
Control Technique ◽  
Shape Model ◽  
Image Velocimetry ◽  
Barrier Discharge Plasma ◽  
Plasma Flow Control ◽  
Active Flow ◽  
Low Speed Wind Tunnel

This experimental investigation presents a new active flow control technique based on plasma actuators applied to a backward facing step whose structure is similar to that formed by the hangar and flight deck of small naval vessels. These experiments were carried out by testing a simple frigate shape model settled at 0° wind over deck in a low-speed wind tunnel. Two different configurations of dielectric barrier discharge plasma actuator have been used to modify the flow downstream of the step. Results obtained investigating the flow by particle image velocimetry prove the capacity of plasma actuators by reducing instabilities and turbulence over the simple frigate shape model.

A comparison of different unsteady flow control techniques in a highly loaded compressor cascade

2018 ◽  
Vol 233 (6) ◽  
pp. 2051-2065 ◽  
Author(s):  
Hongxin Zhang ◽  
Shaowen Chen ◽  
Yun Gong ◽  
Songtao Wang
Keyword(s):  
Unsteady Flow ◽  
Flow Control ◽  
Flow Separation ◽  
Synthetic Jet ◽  
Control Technique ◽  
Compressor Cascade ◽  
Optimum Result ◽  
Control Techniques ◽  
Constant Suction ◽  
Highly Loaded

A numerical research is applied to investigate the effect of controlling the flow separation in a certain highly loaded compressor cascade using different unsteady flow control techniques. Firstly, unsteady pulsed suction as a new novel unsteady flow control technique was proposed and compared to steady constant suction in the control of flow separation. A more exciting effect of controlling the flow separation and enhancing the aerodynamic performance for unsteady pulsed suction was obtained compared to steady constant suction with the same time-averaged suction flow rate. Simultaneously, with the view to further exploring the potential of unsteady flow control technique, unsteady pulsed suction, unsteady pulsed blowing, and unsteady synthetic jet (three unsteady flow control techniques) are analyzed comparatively in detail by the related unsteady aerodynamic parameters such as excitation location, frequency, and amplitude. The results show that unsteady pulsed suction shows greater advantage than unsteady pulsed blowing and unsteady synthetic jet in controlling the flow separation. Unsteady pulsed suction and unsteady synthetic jet have a wider range of excitation location obtaining positive effects than unsteady pulsed blowing. The ranges of excitation frequency and excitation amplitude for unsteady pulsed suction gaining favorable effects are both much wider than that of unsteady pulsed blowing and unsteady synthetic jet. The optimum frequencies of unsteady pulsed suction, unsteady pulsed blowing, and unsteady synthetic jet are found to be different, but these optimum frequencies are all an integer multiple of the natural frequency of vortex shedding. The total pressure loss coefficient is reduced by 16.98%, 16.55%, and 17.38%, respectively, when excitation location, frequency, and amplitude are all their own optimal values for unsteady pulsed suction, unsteady pulsed blowing, and unsteady synthetic jet. The optimum result of unsteady synthetic jet only slightly outperforms that of unsteady pulsed suction and unsteady pulsed blowing. But unfortunately, there is no advantage from the standpoint of overall efficiency for the optimum result of unsteady synthetic jet because the slight improvement has to require a greater power consumption than the unsteady pulsed suction and unsteady pulsed blowing methods.

scholarly journals Flow with nanoparticle clustering controlled by optical forces in quartz glass nanoslits

2019 ◽  
Vol 23 (11) ◽  
Author(s):  
Tetsuro Tsuji ◽  
Yuki Matsumoto ◽  
Satoyuki Kawano
Keyword(s):  
Flow Control ◽  
Quartz Glass ◽  
Target Material ◽  
Optical Force ◽  
Control Technique ◽  
Intermittent Flow ◽  
Channel Height ◽  
Optical Forces ◽  
Sudden Contraction ◽  
Nanofluidic Devices

Abstract In this paper, we demonstrate nanoparticle flow control using an optical force in a confined nanospace. Using nanofabrication technologies, all-quartz-glass nanoslit channels with a sudden contraction are developed. Because the nanoslit height is comparable to the nanoparticle diameter, the motion of particles is restricted in the channel height direction, resulting in almost two-dimensional particle motion. The laser irradiates at the entrance of the sudden contraction channel, leading the trapped nanoparticles to form a cluster. As a result, the translocation of nanoparticles into the contraction channel is suppressed. Because the particle translocation restarts when the laser irradiation is stopped, we can control the nanoparticle flow into the contraction channel by switching the trapping and release of particles, realizing an intermittent flow of nanoparticles. Such a particle flow control technique in a confined nanospace is expected to improve the functions of nanofluidic devices by transporting a target material selectively to a desired location in the device.

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