Plane Poiseuille flow of miscible layers with different viscosities: instabilities in the Stokes flow regime

2011 ◽  
Vol 686 ◽  
pp. 484-506 ◽  
Author(s):  
L. Talon ◽  
E. Meiburg
Keyword(s):  
Flow Regime ◽  
Stokes Flow ◽  
Poiseuille Flow ◽  
Long Wave ◽  
Interface Location ◽  
Large Growth ◽  
Diffusive Modes ◽  
Reynolds Number Flows ◽  
Sharp Interfaces ◽  
And Diffusion

AbstractWe investigate the linear stability of miscible, viscosity-layered Poiseuille flow. In the Stokes flow regime, diffusion is observed to have a destabilizing effect very similar to that of inertia in finite-Reynolds-number flows. For two-layer flows, four types of instability can dominate, depending on the interface location. Two interfacial modes exhibit large growth rates, while two additional bulk modes grow more slowly. Three-layer Stokes flows give rise to diffusive modes for each interface. These two diffusive interface modes can be in resonance, thereby enhancing the growth rate. Furthermore, modes without inertia and diffusion are also observed, consistent with a previous long-wave analysis for sharp interfaces. In contrast to that earlier investigation, the present analysis demonstrates that instability can also occur when the more viscous layer is in the centre, at larger wavenumbers.

scholarly journals Universality in statistics of Stokes flow over a no-slip wall with random roughness

2019 ◽  
Vol 862 ◽  
pp. 1084-1104
Author(s):  
Vladimir Parfenyev ◽  
Sergey Belan ◽  
Vladimir Lebedev
Keyword(s):  
Reynolds Number ◽  
Stokes Flow ◽  
Low Reynolds Number ◽  
Rapid Development ◽  
Fluid Velocity ◽  
Flow Properties ◽  
Random Roughness ◽  
Low Reynolds Number Flows ◽  
And Control ◽  
Reynolds Number Flows

Stochastic roughness is a widespread feature of natural surfaces and is an inherent byproduct of most fabrication techniques. In view of the rapid development of microfluidics, the important question is how this inevitable problem affects the low-Reynolds-number flows that are common for micro-devices. Moreover, one could potentially turn the flaw into a virtue and control the flow properties by means of specially ‘tuned’ random roughness. In this paper we investigate theoretically the statistics of fluctuations in fluid velocity produced by the waviness irregularities at the surface of a no-slip wall. Particular emphasis is laid on the issue of the universality of our findings.

Intermittent Flow Modeling: Part 2—Time-Varying Flows and Flows in Variable Area Ducts

2010 ◽  
Author(s):  
J. P. Abraham ◽  
E. M. Sparrow ◽  
J. C. K. Tong ◽  
W. J. Minkowycz
Keyword(s):  
Reynolds Number ◽  
Flow Regime ◽  
Turbulent Flows ◽  
Intermittent Flow ◽  
Steady Regime ◽  
Cross Sectional ◽  
Friction Factors ◽  
Pass Through ◽  
Different Diameters ◽  
Reynolds Number Flows

The all-flow-regime model of fluid flow, previously applied in [1] to flows with axially and temporally uniform Reynolds numbers, has been implemented here for flows in which the Reynolds number may either vary with time or along the length of a pipe. In the former situation, the timewise variations were driven by a harmonically oscillating inlet flow. These oscillations created a succession of flow-regime transitions encompassing purely laminar and purely turbulent flows as well as laminarizing and turbulentizing flows where intermittency prevailed. The period of the oscillations was increased parametrically until the quasi-steady regime was attained. The predicted quasi-steady friction factors were found to be in excellent agreement with those from a simple model under which the flow is assumed to pass through a sequence of instantaneous steady states. In the second category of non-constant-Reynolds-number flows, axial variations of a steady flow were created by means of a finite-length conical enlargement which connected a pair of pipes of constant but different diameters. The presence of the cross-sectional enlargement gives rise to a reduction of the Reynolds number that is proportional to the ratio of the diameters of the upstream and the downstream pipes. Depending on the magnitude of the upstream inlet Reynolds number, the downstream fully developed flow could variously be laminar, intermittent, or turbulent. The presence or absence of flow separation in the conical enlargement had a direct effect on the laminarization process. For both categories of non-constant-Reynolds-number flows, laminarization and turbulentization were quantified by the ratio of the rate of turbulence production to the rate of turbulence destruction.

Nonlinear hydrodynamic phenomena in Stokes flow regime

2010 ◽  
Vol 239 (14) ◽  
pp. 1214-1224 ◽  
Author(s):  
J. Blawzdziewicz ◽  
R.H. Goodman ◽  
N. Khurana ◽  
E. Wajnryb ◽  
Y.-N. Young
Keyword(s):  
Flow Regime ◽  
Stokes Flow

Heat Transfer Enhancement of Reactor Utilizing Taylor-Poiseuille Flow

2014 ◽  
Author(s):  
Li Ye ◽  
Huajun Peng ◽  
Bo Zhou ◽  
Mo Yang ◽  
Zheng Li ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Flow Regime ◽  
Poiseuille Flow ◽  
Axial Flow ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Taylor Number ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

Numerical studies have been conducted to determine the heat transfer performances in a Taylor-Poiseuille flow regime. The flow is confined between two different heated, concentric cylinders. The inner cylinder is allowed to rotate while the outer one remains fixed, an axial flow is added. The influences of rotation Taylor number and axial Reynolds number on heat transfer coefficients are investigated. Results show that temperature in the flow regime presents a remarkable sinusoidal periodicity as the result of the axial arrangement of Taylor vortices, so does the local heat transfer coefficients. Heat transfer efficiency gets strengthened with increasing Taylor number, while damped with increasing Reynolds number. The accuracy of the simulation is validated by compared to the existing linear stability analysis.

Double-Layer Representation of Model Microorganisms by a Boundary Element Method

2012 ◽  
Author(s):  
Kohei Kyoya ◽  
Yohsuke Imai ◽  
Takami Yamaguchi ◽  
Takuji Ishikawa
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Flow Regime ◽  
Double Layer ◽  
Stokes Flow ◽  
Biomedical Engineering ◽  
Many Body ◽  
Body Interaction ◽  
Many Body Interactions ◽  
Element Method

Analysis of a suspension of microorganisms is important in environmental and biomedical engineering. Previous studies had problems of high computational load in simulating many-body interaction of non-spherical swimmers. In this study, we propose a boundary element method (BEM), based on the double-layer representation, for calculating interactions of two squirmers in Stokes flow regime. By comparing the trajectories of squirmers calculated by both single- and double-layer representations, we show the accuracy of the method. The developed method has potential to deal with many-body interactions of non-spherical microorganisms.

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