The base-flow and near-wake problem at very low Reynolds numbers - Part 1. The Stokes approximation

1965 ◽  
Vol 23 (03) ◽  
pp. 417 ◽  
Author(s):  
H. Viviand ◽  
S.A. Berger
Keyword(s):  
Reynolds Numbers ◽  
Base Flow ◽  
Near Wake ◽  
Low Reynolds Numbers ◽  
Stokes Approximation ◽  
Low Reynolds

The base-flow and near-wake problem at very low Reynolds numbers Part 2. The Oseen approximation

1965 ◽  
Vol 23 (03) ◽  
pp. 439 ◽  
Author(s):  
H. Viviand ◽  
S. A. Berger
Keyword(s):  
Reynolds Numbers ◽  
Base Flow ◽  
Near Wake ◽  
Low Reynolds Numbers ◽  
Oseen Approximation ◽  
Low Reynolds

Behavior of turbulence in the near wake of a thin flat plate at low Reynolds numbers

1992 ◽  
Vol 4 (10) ◽  
pp. 2282-2291 ◽  
Author(s):  
Michio Hayakawa ◽  
Sei‐ichi Iida
Keyword(s):  
Flat Plate ◽  
Reynolds Numbers ◽  
Near Wake ◽  
Low Reynolds Numbers ◽  
Low Reynolds

An Electrokinetic Micro Mixer for Lab-on-Chip Applications: Modeling, Validation, and Optimization

2011 ◽  
Author(s):  
Hendryk Bockelmann ◽  
Vincent Heuveline ◽  
Peter Ehrhard ◽  
Dominik P. J. Barz
Keyword(s):  
Electrical Potential ◽  
Reynolds Numbers ◽  
Base Flow ◽  
Secondary Flows ◽  
Electrical Field ◽  
Lab On Chip ◽  
Low Reynolds Numbers ◽  
Micro Particle Image Velocimetry ◽  
Low Reynolds ◽  
Micro Mixer

Mixing of liquids in micro mixers at low Reynolds numbers is a challenging task since the flow regime is laminar and it is difficult to engage instabilities of the flow. In many microfluidic systems, mixing can be improved by means of electrokinetic effects. A favorable micro mixer design consists of a Y-junction, where the different liquid streams merge, and a subsequent meandering microchannel. A pressure gradient pumps the liquids to be mixed through the microchannel. An oscillating electrical field is superimposed onto the pressure-driven base flow which generates an additional electrokinetic (electro osmotic) flow. These oscillating secondary flows in conjunction with the meandering geometry are responsible for stretching and folding of the contact area of the liquids to be mixed which enhances the mass transfer rates considerably. In this contribution, we present a mathematical model which allows for the numerical simulation of flow, electrical potential, and species concentration. The model is validated by experiments relying on Micro Particle Image Velocimetry (μPIV). Consequently, this model can be used to numerically optimize the electrical field in order to achieve fast and high mixing even at low Reynolds numbers.

A note on bluff body vortex formation

1995 ◽  
Vol 284 ◽  
pp. 217-224 ◽  
Author(s):  
Owen M. Griffin
Keyword(s):  
Bluff Body ◽  
Vortex Formation ◽  
Reynolds Numbers ◽  
Initial Position ◽  
Bluff Bodies ◽  
Near Wake ◽  
Formation Region ◽  
Low Reynolds Numbers ◽  
Region Length ◽  
Low Reynolds

Green & Gerrard (1993) have presented in a recent paper the results of experiments to measure the distribution of vorticity in the near wake of a circular cylinder at low Reynolds numbers (up to Re = 220). They also compared the various definitions of the vortex formation region length which have been proposed by Gerrard (1966), Griffin (1974), and others for both high and low Reynolds numbers. The purpose of this note is to expand the work of Green & Gerrard, and to further their proposition that the end of the vortex formation region at all Reynolds numbers mark both the initial position of the fully shed vortex and the location at which its strength is a maximum. The agreement discussed here between several definitions for the formation region length will allow further understanding to be gained from investigations of the vortex wakes of stationary bluff bodies, and the wakes of oscillating bodies as well.

Global Linear Instability of Flow Through a Converging–Diverging Channel

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Mamta R. Jotkar ◽  
Gayathri Swaminathan ◽  
Kirti Chandra Sahu ◽  
Rama Govindarajan
Keyword(s):  
Reynolds Numbers ◽  
Linear Instability ◽  
Stability Study ◽  
Base Flow ◽  
Low Reynolds Numbers ◽  
Critical Reynolds Numbers ◽  
Diverging Channel ◽  
Order Of Magnitude ◽  
Flow Through ◽  
Low Reynolds

The global linear stability, where we assume no homogeneity in either of the spatial directions, of a two-dimensional laminar base flow through a spatially periodic converging–diverging channel is studied at low Reynolds numbers. A large wall-waviness amplitude is used to achieve instability at critical Reynolds numbers below ten. This is in contrast to earlier studies, which were at lower wall-waviness amplitude and had critical Reynolds numbers an order of magnitude higher. Moreover, our leading mode is a symmetry-breaking standing mode, unlike the traveling modes which are standard at higher Reynolds numbers. Eigenvalues in the spectrum lie on distinct branches, showing varied structure spanning the geometry. Our global stability study suggests that such modes can be tailored to give enhanced mixing in microchannels at low Reynolds numbers.

Vorticity measurements in the near wake of a circular cylinder at low Reynolds numbers

1993 ◽  
Vol 246 ◽  
pp. 675-691 ◽  
Author(s):  
R. B. Green ◽  
J. H. Gerrard
Keyword(s):  
Reynolds Number ◽  
Vortex Shedding ◽  
Bluff Body ◽  
Low Reynolds Number ◽  
Reynolds Numbers ◽  
Near Wake ◽  
Low Reynolds Numbers ◽  
Region Length ◽  
Low Reynolds ◽  
Definition Of

The technique of the particle streak method has been applied to the study of bluff-body wakes at low Reynolds number. Vorticity and shear stress were measured to an accuracy of 15–20%. The vortex shedding cycles at Reynolds number of 73 and 226 are shown and the differences between the two are highlighted. Quantitative descriptions of the previously described vortex splitting phenomenon in the near wake are made, which leads to a description of the vortex shedding mechanism at low Reynolds number. The definition of low-Reynolds-number formation region length is examined. The strength of shed vortices obtained from integration of the vorticity is compared with directly measured vortex strengths and with the results of two-dimensional numerical analysis.

Characteristics of the near wake of a cylinder at low Reynolds numbers

1999 ◽  
Vol 18 (4) ◽  
pp. 659-674 ◽  
Author(s):  
P. Paranthoën ◽  
L.W.B. Browne ◽  
S. Le Masson ◽  
F. Dumouchel ◽  
J.C. Lecordier
Keyword(s):  
Reynolds Numbers ◽  
Near Wake ◽  
Low Reynolds Numbers ◽  
Low Reynolds

Smoke-wire flow visualization of the near-wake region behind a circular disc at low Reynolds numbers

1994 ◽  
Vol 17 (4) ◽  
pp. 259-266 ◽  
Author(s):  
R. F. Huang ◽  
C. F. Chen ◽  
C. L. Lin ◽  
G. M. Bear
Keyword(s):  
Flow Visualization ◽  
Reynolds Numbers ◽  
Circular Disc ◽  
Wake Region ◽  
Near Wake ◽  
Low Reynolds Numbers ◽  
Low Reynolds
Sign in / Sign up

Export Citation Format

Share Document