Diffusion in oscillatory pipe flow

Journal of Fluid Mechanics ◽

10.1017/s0022112083001883 ◽

1983 ◽

Vol 133 ◽

pp. 233-244 ◽

Cited By ~ 191

Author(s):

E. J. Watson

Keyword(s):

Mass Transfer ◽

Cross Section ◽

Pipe Flow ◽

Oscillatory Motion ◽

Circular Pipe ◽

Two Dimensional ◽

Ambient Fluid ◽

Fast Oscillations

The rate of mass transfer of a diffusing substance along a pipe is augmented by an oscillatory motion of the ambient fluid in the pipe. The increase of the flux is evaluated for the cases of a circular pipe and of a two-dimensional channel. Results are given for a general cross-section in the limiting cases of slow and fast oscillations of the flow.

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Computational Study of Zigzag Spacer Design with Elliptical Cross-Section Filaments

MATEC Web of Conferences ◽

10.1051/matecconf/202030701047 ◽

2020 ◽

Vol 307 ◽

pp. 01047

Author(s):

Gohar Shoukat ◽

Farhan Ellahi ◽

Muhammad Sajid ◽

Emad Uddin

Keyword(s):

Mass Transfer ◽

Cross Section ◽

Cross Sections ◽

Computational Study ◽

Flow Direction ◽

Three Dimensional ◽

Circular Cross Section ◽

Two Dimensional ◽

Permeate Flux ◽

Elliptical Cross

The large energy consumption of membrane desalination process has encouraged researchers to explore different spacer designs using Computational Fluid Dynamics (CFD) for maximizing permeate per unit of energy consumed. In previous studies of zigzag spacer designs, the filaments are modeled as circular cross sections in a two-dimensional geometry under the assumption that the flow is oriented normal to the filaments. In this work, we consider the 45° orientation of the flow towards the three-dimensional zigzag spacer unit, which projects the circular cross section of the filament as elliptical in a simplified two-dimensional domain. OpenFOAM was used to simulate the mass transfer enhancement in a reverse-osmosis desalination unit employing spiral wound membranes lined with zigzag spacer filaments. Properties that impact the concentration polarization and hence permeate flux were analyzed in the domain with elliptical filaments as well as a domain with circular filaments to draw suitable comparisons. The range of variation in characteristic parameters across the domain between the two different configurations is determined. It was concluded that ignoring the elliptical projection of circular filaments to the flow direction, can introduce significant margin of error in the estimation of mass transfer coefficient.

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Mean Flow Downstream of Two-Dimensional Roughness Elements

Journal of Fluids Engineering ◽

10.1115/1.3243615 ◽

1989 ◽

Vol 111 (2) ◽

pp. 149-153 ◽

Cited By ~ 6

Author(s):

E. Logan ◽

P. Phataraphruk

Keyword(s):

Reynolds Number ◽

Cross Section ◽

Pipe Flow ◽

Rectangular Cross Section ◽

Roughness Element ◽

Two Dimensional ◽

Hot Wire ◽

Mean Flow ◽

Roughness Elements ◽

Three Stages

The response of a fully developed pipe flow to wall mounted roughness elements of rectangular cross section was investigated experimentally using a probe with a single hot-wire. Four heights of rectangular, ring-type elements were installed rigidly in a 63.5-mm diameter, smooth-walled, circular pipe in which air was flowing at a Reynolds number of 50,000. After passing over the roughness element, the flow recovery occurred in three stages. The three flow regions are delineated, and the velocity profiles for each are correlated.

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