Local resistance of fluid flow across sudden contraction in small channels

In studying the fluid flow and heat transfer in microchannels and minichannels, various claims have been made regarding transition at Reynolds numbers significantly below 2300. As a first step in identifying the reasons for such reports on early transition, the effect of entrance geometry on the pressure drop and transition to turbulence was studied in a conventional channel of 19 mm inside diameter (Kandlikar and Campbell [1]). As a second step, the effect of entrance condition on pressure drop and transition to turbulence is studied in small channels with diameters of 1.067 mm and 0.457 mm. The two entrance conditions employed for both channels are re-entrant and smooth. The experimental results show the effect of entrance condition on local friction factor, transition Reynolds number, and Hagenbach’s factor.

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Two-Phase Flow Pressure Change Across Sudden Contraction and Expansion in Small Channels

Advances in Multiphase Flow and Heat Transfer (Volume 3) ◽

10.2174/978160805228811203010055 ◽

2012 ◽

pp. 55-83

Author(s):

Ing Youn Chen ◽

Chih-Yung Tseng ◽

Chi-Chuan Wang

Keyword(s):

Two Phase Flow ◽

Pressure Change ◽

Phase Flow ◽

Two Phase ◽

Sudden Contraction ◽

Flow Pressure ◽

Small Channels ◽

Contraction And Expansion

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Bifurcation of a Newtonian-fluid flow in a planar channel with sudden contraction and expansion

Doklady Physics ◽

10.1134/s1028335817030089 ◽

2017 ◽

Vol 62 (3) ◽

pp. 145-148 ◽

Cited By ~ 5

Author(s):

S. A. Patlazhan ◽

I. V. Kravchenko ◽

R. Muller ◽

Y. Hoarau ◽

Y. Remond ◽

...

Keyword(s):

Fluid Flow ◽

Newtonian Fluid ◽

Planar Channel ◽

Sudden Contraction ◽

Contraction And Expansion

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Complex Biological Fluid Flow Through Microfabricated Polysilicon Microneedles

10.1115/imece2000-1158 ◽

2000 ◽

Author(s):

Jeffrey D. Zahn ◽

Dorian Liepmann

Keyword(s):

Fluid Flow ◽

Biological Fluid ◽

Biological Fluids ◽

Sample Extraction ◽

Flow Through ◽

Complex Features ◽

Small Channels ◽

Biological Solutions ◽

Phosphate Buffered Saline ◽

Fahraeus Effect

Abstract Microneedles can be used for sample extraction or injection for biomedical applications. It is important to understand how complex biological fluids behave within the needles because non-newtonian effects are associated with fluid flow of concentrated biological solutions. Different concentrations of sheep blood diluted with phosphate buffered saline (PBS) were investigated in different planar needle geometries. Only slight shear thinning behavior was observed, and only slight changes in apparent viscosity were recorded even at higher hematocrit levels. This is hypothesized to be a result of the Fahraeus effect in which cells are excluded from the wall regions in small channels. Microneedles with complex features clogged easily whereas needles with larger hydraulic radii allowed higher concentrations of blood to flow through them. However, at higher hematocrit levels (>25%) even the lower resistance needle clogged. Further investigations are needed to correlate how geometry affects flow of complex cellular suspensions.

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Pressure Losses of Power-Law Fluid Flow through an Axisymmetric Sudden Contraction

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.685.47 ◽

2016 ◽

Vol 685 ◽

pp. 47-50 ◽

Cited By ~ 1

Author(s):

Evgeny Borzenko ◽

Kira Boyarkina ◽

Gennady R. Shrager

Keyword(s):

Fluid Flow ◽

Power Law ◽

Relaxation Method ◽

Local Resistance ◽

Power Law Fluid ◽

Mathematical Statement ◽

Pressure Losses ◽

Contraction Ratio ◽

Flow Through ◽

Resistance Coefficients

In this paper the laminar stationary power-law fluid flow through an axisymmetric pipe contraction is investigated. The mathematical statement of the problem is formulated using stream function and vorticity variables. For obtaining a stationary solution the relaxation method with following realization of numerical algorithm based on finite difference alternative directions scheme is utilized. Implemented parametrical investigations allow obtaining the dependence of local resistance coefficients on Reynolds number, nonlinearity degree and piping contraction ratio.

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