Structural characteristics of dean vortices in a curved channel

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Dean vortices in a curved channel were studied using flow visualization and a miniature Kiel probe to record total pressure. The channel is cm. high by cm. wide ( in. x in.), aspect ratio of 40 to 1, with a radius of curvature of cm.

( in) for the concave surface. Mean velocities within the curve channel were maintained at Dean numbers which ranged from 0 to .1N/abstract. Structural characteristics of dean vortices in a curved channel. By Randal D. Niver Download PDF (4 MB)   Structural Characteristics of Dean Vortices in a Curved Channel by Randal D.

Niver Lieutenant, United States Navy B.S., Arizona State University, Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN MECHANICAL ENGINEERING from the NAVAL POSTGRADUATE SCHOOL June Author: X2 Randal D. Niver The development and structural characteristics of Dean vortices in a curved rectangular channel.

By Lawrence Richard Baun. Download PDF (14 MB) distribution is unlimitedThe development and structure of Dean vortices in a curved channel were measured and studied. A aspect ratio channel with mild curvature was employed. Circulation of Flow visualization of time-varying structural characteristics of Dean vortices in a curved channel distribution is unlimitedThe time varying development and structure of Dean vortices were studies using flow visualization.

Observations were made over a range of Dean numbers from 40 to using a transparent channel with mild curvature, 40 @article{osti_, title = {Dean vortices with wall flux in a curved channel membrane system.

2: The velocity field}, author = {Chung, K Y and Brewster, M E and Belfort, G}, abstractNote = {The velocity and pressure fields and the effect of wall flux on these fields in a spiral channel are presented.

Details Structural characteristics of dean vortices in a curved channel EPUB

As fluid flows inward through a spiral channel with constant gap and permeable walls, the When Dean numbers are high enough, the flow in a curved channel is unstable to centrifugal instabilities, and secondary flows develop which eventually form into pairs of counter-rotating vortices.

This flow is referred to as Dean vortex flow, and the accompanying pairs of streamwiseoriented vortices are referred to as Dean vortices. The present Flow Visualization of Time-Varying Structural Characteristics of Dean Vortices in a Curved Channel by David Wayne Bella Lieutenant, United States Navy B.

S., University of California, Riverside, Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN MECHANICAL ENGINEERING from the NAVAL POSTGRADUATE ?doi=&rep=rep1&type=pdf.

For a short curved channel where area expansion effect dominates, pressure drop for developing flow can be even less than that of a straight channel. A comparison with the flow in a constant c/s area, curved channel shows that the variable c/s area channel geometry leads to a lower critical Dean /Flow-Characteristics-in-a-Curved-Rectangular.

Baun LR () The development and structural characteristics of Dean vortices in a curved rectangular channel. Thesis, Dept. of Mech. Eng., Naval Postgraduate School, Monterey, Ca. Google Scholar The time varying development and structure of Dean vortices were studied using flow visualization.

Observations were made over a range of Dean numbers from 40 to using a transparent channel with mild curvature, aspect ratio, and an inner to outer radius ratio of Seven flow visualization techniques were tried but only one, a wood burning smoke generator, produced usable :// .6B/abstract.

The transition from laminar curved channel Poiseuille flow to axisymmetric Dean vortex flow is studied using linear and weakly nonlinear analyses; these results are compared to the full simulations. Using the code, two transitions that cause the axisymmetric vortices to develop waves travelling in the streamwise direction at higher Reynolds   At Reynolds number Re= Re c temporally periodic wavy (twisting) Dean vortices occur (Re c is the Reynolds number for the transition from laminar curved channel Poiseuille flow to steady, streamwise‐oriented Dean vortices).

At Re= Re c, a three‐frequency flow is discovered in which two new incommensurate frequencies modulate the wavy   In this work, we investigate the fully developed flow field of two vertically stratified fluids (one phase flowing above the other) in a curved channel of rectangular cross section.

The domain perturbation technique is applied to obtain an analytical solution in the asymptotic limit of low Reynolds numbers and small curvature ratios (the ratio of the width of the channel to its radius of   We propose a novel strategy for designing chaotic micromixers using curved channels confined between two flat planes.

The location of the separatrix between the Dean vortices    TITLE (Include Security Classification) THE DEVELOPMENT AND STRUCTURAL CHARACTERISTICS OF DEAN VORTICES IN A CURVED RECTANGULAR CHANNEL PERSONAL AUTHOR(S) Baun Lawrence R.

13a. TYPE OF REPORT 13b. TIME COVERED DATE OF REPORT (Year, Month, Day) 15 PAGE COUNT MasterIs Thesis FROM TO " September I Flow visualization of time-varying structural   In Fig. 5, the onset of Dean Instability occurs within K = 80 to for the rectangular duct while for the Dean vortices between K = to These Dean vortices are designated as the helicity contour corresponding to H* = Upon inception, Dean vortices gradually grow bigger with   Curved channel geometries can induce Dean vortices perpendicular to the direction of flow, 40 P.

Ligrani and R. Niver, “ Flow visualization of Dean vortices in a curved channel with 40 to 1 aspect ratio,” Phys. Flu (). surface. Named after Dean, the flow through a curved channel is quantified by the dimensionless Dean number (De), which is analogous to the Reynolds number (Re) in straight tubes.

The Dean number accounts for the effect of curvature ratio and is defined as De = Re/√λ, where λ is the curvature ratio of the coiled :// A comprehensive analysis of the pressure-gradient driven flow in a meandering channel has been presented.

Description Structural characteristics of dean vortices in a curved channel PDF

This geometry is of interest as it can be used for the creation of streamwise vortices which magnify the transverse transport of scalar quantities, e.g. heat ://   Reset your password. If you have a user account, you will need to reset your password the next time you login.

You will only need to do this :// Non-isothermal flows with convective heat transfer through a curved duct of square cross section are numerically studied by using a spectral method, and covering a wide range of curvature, δ ⁠, 0 Dean number, Dn, 0 ≤ Dn ≤ ⁠.A temperature difference is applied across the vertical sidewalls for the Grashof number Gr = ⁠, where the outer wall is heated and [Show full abstract] channel wall visualizations showed that the Dean vortices develop first in the near-wall zone on the concave (outer) wall, where the shear rate is higher and   Y.

Mori and Y. Uchida, “ Study on forced convective heat transfer in a curved square channel (1st report, theory of laminar region),” Trans.

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Soc. Mech. Eng. 33, (). Google Scholar Crossref; De is the usual Dean number based on the axial mean velocity W ://   Winzeler and Belfort and Brewster et al. proposed using Dean vortices resulting from the centrifugal instabilities generated by flow in a curved channel to improve membrane performance.

Brewster et al. [ 44 ] analyzed the design of a spiral channel configuration for both narrow and wide gaps, accounting for the stabilizing effect of the wall The current research deals with a specially designed curved microfluidic channel used to employ the fluid mixing characteristics of Dean vortices and thus transfer heat more efficiently.

This curved microfluidic channel is deployed as a spiral channel to create an effective heat sink and a heat :// About this book Introduction Yet, as this volume goes to press it has been nearly 70 years since G.

Taylor's outstanding experimental and theoretical study of the linear stability of this flow was published, and a century since the first experiments were performed on rotating cylinder ://   A characteristic feature of fluid flow in a curved conduit is the presence of a secondary flow in the channel cross-section, known as Dean vortices or roll-cells (Dean,Dean, ).

A pair of these counter rotating vortices is formed already at low Reynolds numbers, and it transports fluid elements from the central region of the curved Jian Li's 7 research works with citations and reads, including: Numerical and experimental analyses of planar asymmetric split-and-recombine micromixer with dislocation sub-channels.

Flow visualization of time-varying structural characteristics of Dean vortices in a curved channel. (IA flowvisualizatio00bell).pdf 1, × 1, pages; MB Flow visualization of the airwake of an oscillating generic ship ://:Fluid_dynamics.

Ghia et al. proposed that the significant similarity parameter of flow in curved pipe was Dean number (De = Re(d T /D H) ), rather than Reynolds number. Thus we used Dean number to represent the flow characteristics of molten salt in helical annular duct.

(15) N u l = C 1 D e C 2 P r 1 / 3The present review paper, therefore, is an account on the state-of-the-art research concerning turbulent flow in curved pipes, naturally covering mostly experimental work, while also analytical and numerical works are reviewed. This paper starts with a historical review on pipe flows in general and specifically on flows through curved ://