Flow through curved rectangular channels of large aspect ratio

AIChE Journal ◽  
1995 ◽  
Vol 41 (5) ◽  
pp. 1061-1070 ◽  
Author(s):  
Matthew J. Targett ◽  
William B. Retallick ◽  
Stuart W. Churchill
Keyword(s):  
Aspect Ratio ◽  
Large Aspect Ratio ◽  
Rectangular Channels ◽  
Flow Through

Numerical study of unsteady fluid flow through a tightly coiled rectangular duct of large aspect ratio

2021 ◽  
Author(s):  
Shamsun Naher Dolon ◽  
Mohammad Sanjeed Hasan ◽  
Ratan Kumar Chanda ◽  
Rabindra Nath Mondal
Keyword(s):  
Fluid Flow ◽  
Aspect Ratio ◽  
Numerical Study ◽  
Large Aspect Ratio ◽  
Rectangular Duct ◽  
Unsteady Fluid Flow ◽  
Flow Through ◽  
Unsteady Fluid

Steady flow through distorted rectangular tubes of large aspect ratio

1983 ◽  
Vol 385 (1788) ◽  
pp. 107-127 ◽  
Keyword(s):  
Aspect Ratio ◽  
Boundary Layers ◽  
Rectangular Cross Section ◽  
Two Dimensional ◽  
Large Aspect Ratio ◽  
Dimensional Solution ◽  
Method Of Solution ◽  
Flow Through ◽  
High Reynolds ◽  
Sharp Corners

High Reynolds number ( Re ) flows through large aspect ratio ( λμ ) tubes of rectangular cross section are studied. One wall of the tube is slightly deformed to produce a two-dimensional distortion of length λ . We determine conditions for the flow at the centre of the tube and near the distortion to approximate the appropriate two-dimensional solution: namely, λμ ≫ ( λ -1 Re ) 1/6 if Re 1/7 ≲ λ and μ ≫ 1 if Re 1/7 ≳ λ . However, the latter condition needs to be strengthened to λμ ≫ Re 1/7 if the flow is additionally to be approximately two-dimensional far up- and down-stream. The method of solution includes a numerical calculation for the flow in the sharp corners of the tube. We deduce that for sufficiently short distortions ( λ ≪ Re 1/9 (ln Re ) 11/9 ), the sharp corners can effectively isolate disturbances in the wall boundary layers from each other. However, for larger distortions the disturbances in the boundary layers are all of comparable magnitude owing to interactions at the corners. Our examination of the corner regions also enables us to confirm a hypothesis, due to Hocking (1977) and others, that to leading order the pressure is constant in approximately square regions at the sides of the tube.

scholarly journals The Effects of Magnetic Field on the Fluid Flow through a Rotating Straight Duct with Large Aspect Ratio

2013 ◽  
Vol 56 ◽  
pp. 239-244 ◽  
Author(s):  
Md. Kamruzzaman ◽  
Mohammad Wahiduzzaman ◽  
Md. Mahmud Alam ◽  
Lyazid Djenidi
Keyword(s):  
Magnetic Field ◽  
Fluid Flow ◽  
Aspect Ratio ◽  
Large Aspect Ratio ◽  
Flow Through ◽  
Straight Duct

The effect of aspect ratio on longitudinal diffusivity in rectangular channels

1982 ◽  
Vol 120 ◽  
pp. 347-358 ◽  
Author(s):  
P. C. Chatwin ◽  
Paul J. Sullivan
Keyword(s):  
Laminar Flow ◽  
Aspect Ratio ◽  
Cross Section ◽  
Laboratory Experiments ◽  
Rectangular Cross Section ◽  
Independent Method ◽  
Surprising Result ◽  
Large Aspect Ratio ◽  
Rectangular Channels ◽  
Side Walls

In a recent paper Doshi, Daiya & Gill (1978) showed that the value of Taylor's longitudinal diffusivity D for laminar flow in a channel of rectangular cross-section of breadth u and height b is about 8D0, for large values of the aspect ratio a/b, where Do is the value of the longitudinal diffusivity obtained by ignoring all variation across the channel. This superficially surprising result is confirmed by an independent method, and is shown to be caused by the boundary layers on the side walls of the channel. The primary purpose of the paper, however, is to consider the value of D in turbulent flow in a flat-bottomed channel of large aspect ratio, for which arguments based on physics are adduced in support of the formula D≈[1 + B][1 - λ(b/u)], where B and λ are positive constants independent of b. It is shown that this result is consistent with laboratory experiments by Fischer (1966). The paper concludes with a discussion of the practical effects of aspect ratio on longitudinal dispersion in channels whose cross-section is approximately rectangular.

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