Oscillatory Flow Through a Channel with Stick–Slip Walls: Complex Navier’s Slip Length

2011 ◽  
Author(s):  
Chiu-On Ng ◽  
C. Y. Wang ◽  
Jiachun Li ◽  
Song Fu
Keyword(s):  
Oscillatory Flow ◽  
Slip Length ◽  
Stick Slip ◽  
Navier’S Slip ◽  
Flow Through

Oscillatory Flow Through a Channel With Stick-Slip Walls: Complex Navier’s Slip Length

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
Chiu-On Ng ◽  
C. Y. Wang
Keyword(s):  
Oscillation Frequency ◽  
Oscillatory Flow ◽  
Slip Length ◽  
Complex Nature ◽  
Channel Height ◽  
Boundary Slip ◽  
Stick Slip ◽  
Effective Slip ◽  
Flow Through ◽  
Shear Area

Effective slip lengths for pressure-driven oscillatory flow through a parallel-plate channel with boundary slip are deduced using a semi-analytic method of eigenfunction expansions and point matching. The channel walls are each a superhydrophobic surface micropatterned with no-shear alternating with no-slip stripes, which are aligned either parallel or normal to the flow. The slip lengths are complex quantities that are functions of the oscillation frequency, the channel height, and the no-shear area fraction of the wall. The dependence of the complex nature of the slip length on the oscillation frequency is investigated in particular.

Converting steady laminar flow to oscillatory flow through a hydroelasticity approach at microscales

Lab on a Chip ◽  
2012 ◽  
Vol 12 (1) ◽  
pp. 60-64 ◽  
Author(s):  
H. M. Xia ◽  
Z. P. Wang ◽  
W. Fan ◽  
A. Wijaya ◽  
W. Wang ◽  
...  
Keyword(s):  
Laminar Flow ◽  
Oscillatory Flow ◽  
Flow Through ◽  
Steady Laminar

Heat Transportation by an Oscillatory Flow Through a Parallel-Plate Channel With an Inserted Slanting Plate

2007 ◽  
Author(s):  
Yoshihisa Ishii ◽  
Xiaojin Zhang ◽  
Makoto Hishida
Keyword(s):  
Parallel Plate ◽  
Oscillatory Flow ◽  
Electronic Devices ◽  
Tidal Amplitude ◽  
Womersley Number ◽  
Flow Component ◽  
Directional Flow ◽  
Transportation Channel ◽  
Flow Through ◽  
Plate Channel

Heat transportation devices with small size and high transportation rate are highly required for achieving effective cooling of electronic devices and equipments. Heat transportation devices exploiting reciprocal flow are considered as one of important candidate technologies. Since a heat transportation pipe exploiting reciprocal flow was invented by Kurzweg and Zhao[1], many researchers have attempted to improve its performance. In the present paper we proposed a new concept of heat transportation channel which was a parallel-plate channel with a slanting plate inserted. The slanting plate separated the parallel-plate channel into two tapered channels. We analyzed numerically the heat transportation performance of the channel when a reciprocal flow was given at one end of the channel. Womersley number Wo was varied in a range of 7≤ Wo ≤40 and Remax in a range of 100≤ Remax ≤1300, by changing the tidal amplitude Am of the reciprocal flow from 0.005 to 0.102 m and reciprocal frequency from 0.07 to 2.56Hz. The present study was summarized in the followings: (1) In the present channel, oscillatory flow comprised of a reciprocal flow component superimposed on a one-directional flow component was induced. (2) u-velocity profiles in pushing phase and in pulling phase were not symmetrical when Wo was relatively small or Remax was large. They approached symmetrical profile in large Wo range and in small Remax range. (3) The time-averaged flow rate V remained almost constant in the Wo range from 7 to 20. They decreased with increasing Wo beyond 20. It also decreased with decreasing Remax. (4) Heat transportation rate Q and heat transportation efficiency η decreased with increasing Wo and decreasing Remax. (5) Work rate W increased with increasing Wo and Remax. (6) The present heat transportation channel was able to transport about 5 to 13 times the heat with 1.4 to 4 times the efficiency by only inserting a slanting plate in a hollow parallel-plate channel.

Identifying the Mechanisms of Enhanced Water Flow Through Carbon Nanotubes

2008 ◽  
Author(s):  
J. A. Thomas ◽  
A. J. H. McGaughey
Keyword(s):  
Carbon Nanotubes ◽  
Water Flow ◽  
Flow Rate ◽  
Driving Force ◽  
Slip Length ◽  
Dynamics Simulation ◽  
Flow Area ◽  
Water Viscosity ◽  
Flow Through ◽  
External Driving

Pressure-driven water flow through carbon nanotubes (CNTs) with diameters ranging from 1.66 nm to 4.99 nm is examined using molecular dynamics simulation. The flow rate enhancement, defined as the ratio of the observed flow rate to that predicted from the no-slip Hagen-Poiseuille relation, is calculated for each CNT. The enhancement decreases with increasing CNT diameter and ranges from 433 to 47. By calculating the variation of water viscosity and slip length as a function of CNT diameter, it is found that the results can be fully explained in the context of continuum fluid mechanics. The enhancements are lower than previously reported experimental results, which range from 560 to 100000, suggesting a miscalculation of the available flow area and/or the presence of an uncontrolled external driving force (such as an electric field) in the experiments.

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