Transport and efficiency of Brownian particles in confined narrow channels with a periodic driving force

2015 ◽  
Vol 29 (05) ◽  
pp. 1550026 ◽  
Author(s):  
Rang Wang ◽  
Jia-Ning Zhou ◽  
Xue-Mei Liu ◽  
Hua Xiao
Keyword(s):  
External Force ◽  
Driving Force ◽  
Average Velocity ◽  
Static Load ◽  
Narrow Channel ◽  
Load Force ◽  
Narrow Channels ◽  
Brownian Particles ◽  
Peaked Function ◽  
External Driving

Transport and efficiency of over-damped Brownian particles moving in a confined narrow channel is investigated in the presence of an oscillating force and a static load force. It is found that the average velocity increases monotonously with the unbiased external driving force, while the efficiency can be a peaked function of unbiased external force, which indicates that the unbiased external force can facilitate the efficiency of energy transformation. Moreover, the average velocity and the efficiency demonstrate complex behaviors due to the consideration of Stokes efficiency.

Transport performance of feedback-coupled Brownian ratchets with closed-loop control strategy

2015 ◽  
Vol 29 (12) ◽  
pp. 1550069
Author(s):  
T. F. Gao ◽  
L. F. Wang ◽  
R. Z. Huang ◽  
Z. G. Zheng
Keyword(s):  
Diffusion Coefficient ◽  
External Force ◽  
Average Velocity ◽  
Thermal Noise ◽  
Periodic Force ◽  
Average Diffusion Coefficient ◽  
Brownian Particles ◽  
Average Diffusion ◽  
Time Periodic ◽  
Ratchet Potential

The transport performance of two feedback-coupled Brownian particles, which are subjected to the external force, the unbiased time-periodic force and thermal noise, is investigated in the double-well ratchet potential. The average velocity, the average diffusion coefficient and the Pe number are calculated, respectively. The results demonstrate that the transport characteristic of Brownian particles is different under the action of two factors of unbiased time-periodic force, amplitude and frequency. The former factor induces the increase of the average velocity and the average diffusion coefficient with the decrease of thermal noise intensity within certain limits, whereas the latter makes the average velocity decrease in the transport of coupled particles. Moreover, it is found there is an optimal value of the driving frequency at which the Pe number reaches its maximum. Remarkably, it is shown that the current reversal can be achieved by increasing the external force, and the directed transport can be enhanced by varying the structure of the ratchet potential and the intensity of noise.

DIRECTED MOTION INDUCED BY SHIFTING RATCHET

2000 ◽  
Vol 14 (24) ◽  
pp. 2609-2616 ◽  
Author(s):  
YUXIAO LI ◽  
XIZHEN WU ◽  
YIZHONG ZHUO
Keyword(s):  
Driving Force ◽  
Transition Rate ◽  
Average Velocity ◽  
Thermal Noise ◽  
Periodic Potential ◽  
Directed Motion ◽  
Brownian Particles

The motion of Brownian particles in a spatial asymmetric periodic potential is considered. In the absence of any external macroscopic driving force, when the potential transits stochastically between two configurations which are shifted by a distance relative to each other, directed motion can be induced. The dependence of the average velocity on the transition rate, the strength of thermal noise and the shift distance between the two configurations of potential are analyzed. The efficiency of the system is evaluated.

Development of Advanced High Heat Flux Cooling System for Power Electronics

2009 ◽  
Author(s):  
Yasuhisa Shinmoto ◽  
Shinichi Miura ◽  
Koichi Suzuki ◽  
Yoshiyuki Abe ◽  
Haruhiko Ohta
Keyword(s):  
Heat Flux ◽  
Power Electronics ◽  
Critical Heat Flux ◽  
Heating Surface ◽  
Narrow Channel ◽  
High Heat ◽  
High Heat Flux ◽  
Gap Size ◽  
Narrow Channels ◽  
Very High

Recent development in electronic devices with increased heat dissipation requires severe cooling conditions and an efficient method for heat removal is needed for the cooling under high heat flux conditions. Most researches are concentrated on small semiconductors with high heat flux density, while almost no existing researches concerning the cooling of a large semiconductor, i.e. power electronics, with high heat generation density from a large cooling area. A narrow channel between parallel plates is one of ideal structures for the application of boiling phenomena which uses the cooling for such large semiconductors. To develop high-performance cooling systems for power electronics, experiments on increase in critical heat flux (CHF) for flow boiling in narrow channels by improved liquid supply was conducted. To realize the cooling of large areas at extremely high heat flux under the conditions for a minimum gap size and a minimum flow rate of liquid supplied, the structure with auxiliary liquid supply was devised to prevent the extension of dry-patches underneath flattened bubbles generated in a narrow channel. The heating surface was experimented in two channels with different dimensions. The heating surfaces have the width of 30mm and the lengths of 50mm and 150mm in the flow direction. A large width of actual power electronics is realizable by the parallel installation of the same channel structure in the transverse direction. The cooling liquid is additionally supplied via sintered metal plates from the auxiliary unheated channels located at sides or behind the main heated channel. To supply the liquid to the entire heating surface, fine grooves are machined on the heating surface for enhance the spontaneous liquid supply by the aid of capillary force. The gap size of narrow channels are varied as 0.7mm, 2mm and 5mm. Distribution of liquid flow rate to the main heated channel and the auxiliary unheated channels were varied to investigate its effect on the critical heat flux. Test liquids employed are R113, FC72 and water. The systematic experiments by using water as a test liquid were conducted. Critical heat flux values larger than 2×106W/m2 were obtained at both gap sizes of 2mm and 5mm for a heated length of 150mm. A very high heat transfer coefficient as much as 1×105W/m2K was obtained at very high heat flux near CHF for the gap size of 2mm. This paper is a summary of experimental results obtained in the past by the present authors.

Visualization of Boiling in Inclined Rectangular Narrow Long Channels

2006 ◽  
Author(s):  
Sang W. Noh ◽  
Jae S. Yoo ◽  
Kune Y. Suh
Keyword(s):  
Inclination Angle ◽  
Atmospheric Pressure ◽  
Narrow Channel ◽  
Vertical Position ◽  
Bubble Behavior ◽  
Water Pool ◽  
Narrow Channels ◽  
Saturated Water ◽  
Test Parameters ◽  
Reactor Pressure

During the Three-Mile Island Unit 2 (TMI-2) accident, the lower part of the reactor pressure vessel had been overheated and then rather rapidly cooled down, as it was later found out in a vessel investigation project. These findings triggered a great deal of investigations to determine the critical heat flux (CHF) in narrow channels. Experiments were conducted to determine the CHF on a long downward heated rectangular narrow channel by changing the orientation of a copper crevice (5×105 mm2) type heater assembly. The test heater was placed in a demineralized, saturated water pool at atmospheric pressure. This work aims also to investigate the general boiling phenomena and the triggering mechanism for the CHF in the narrow channel through visualization of the bubble behavior in the vicinity of CHF. The test parameters include the channel size of 5 mm and the surface orientation angles from the downward facing position (180°) to the vertical position (90°). It was found that the CHF decreases as the surface inclination angle increases and as the gap size decreases. It was also shown that there exists a transition angle at which the CHF changes with a rapid slope, and that the inclination angle affects the bubble layer and the bubble discharge from the narrow gap.

Study of Flow-Induced Vibrations of a Plate in Narrow Channels

1967 ◽  
Vol 89 (4) ◽  
pp. 824-830 ◽  
Author(s):  
S. R. Bland ◽  
R. H. Rhyne ◽  
H. B. Pierce
Keyword(s):  
Rocket Engine ◽  
Strong Dependence ◽  
Narrow Channel ◽  
Two Dimensional ◽  
Rigid Plate ◽  
Narrow Channels ◽  
The Core ◽  
Flow Induced Vibrations ◽  
Nuclear Rocket ◽  
Time Of Failure

Vibration phenomena associated with narrow channel flow have come under study as a result of the core failure of an early nuclear rocket engine. Since the mechanism of this vibration instability was not well understood at the time of failure, an investigation of a simple system consisting of a rigid plate with two degrees of spring-restrained freedom in a two-dimensional channel has been made both experimentally and analytically. The results show a strong dependence of the flow rate required for plate oscillation on the channel width (normal to plate).

Molecular dynamics simulation studies on the plastic behaviors of an iron nanowire under torsion

RSC Advances ◽  
2016 ◽  
Vol 6 (34) ◽  
pp. 28792-28800 ◽  
Author(s):  
Chong Qiao ◽  
Yanli Zhou ◽  
Xiaolin Cai ◽  
Weiyang Yu ◽  
Bingjie Du ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Molecular Dynamics Simulation ◽  
Deformation Mechanism ◽  
Driving Force ◽  
Dynamics Simulation ◽  
Simulation Studies ◽  
Plastic Deformation Mechanism ◽  
Constant Torsion ◽  
External Driving

The plastic deformation mechanism of iron (Fe) nanowires under torsion is studied using the molecular dynamics (MD) method by applying an external driving force at a constant torsion speed.

scholarly journals Interface Roughening with a Time-Varying External Driving Force

1993 ◽  
Vol 21 (4) ◽  
pp. 401-406 ◽  
Author(s):  
E Hernández-García ◽  
T Ala-Nissila ◽  
M Grant
Keyword(s):  
Driving Force ◽  
Time Varying ◽  
Interface Roughening ◽  
External Driving
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