Laminar Entrance Region Flow of Herschel-Bulkley Fluids in a Circular Pipe

2002 ◽  
Vol 22 (3) ◽  
Author(s):  
Ramesh C. Gupta
Keyword(s):  
Entrance Region ◽  
Circular Pipe ◽  
Region Flow

Entrance region flow of the Bingham fluid in a circular pipe

AIChE Journal ◽  
1970 ◽  
Vol 16 (2) ◽  
pp. 293-299 ◽  
Author(s):  
S. S. Chen ◽  
L. T. Fan ◽  
C. L. Hwang
Keyword(s):  
Bingham Fluid ◽  
Entrance Region ◽  
Circular Pipe ◽  
Region Flow

Growth of vortical disturbances entrained in the entrance region of a circular pipe

2021 ◽  
Vol 932 ◽  
Author(s):  
Pierre Ricco ◽  
Claudia Alvarenga
Keyword(s):  
Reynolds Number ◽  
Initial Conditions ◽  
Maximum Growth ◽  
Streamwise Velocity ◽  
Velocity Profiles ◽  
Boundary Region ◽  
Base Flow ◽  
Entrance Region ◽  
Circular Pipe ◽  
Large Reynolds Number

The development and growth of unsteady three-dimensional vortical disturbances entrained in the entry region of a circular pipe is investigated by asymptotic and numerical methods for Reynolds numbers between $1000$ and $10\,000$ , based on the pipe radius and the bulk velocity. Near the pipe mouth, composite asymptotic solutions describe the dynamics of the oncoming disturbances, revealing how these disturbances are altered by the viscous layer attached to the pipe wall. The perturbation velocity profiles near the pipe mouth are employed as rigorous initial conditions for the boundary-region equations, which describe the flow in the limit of low frequency and large Reynolds number. The disturbance flow is initially primarily present within the base-flow boundary layer in the form of streamwise-elongated vortical structures, i.e. the streamwise velocity component displays an intense algebraic growth, while the cross-flow velocity components decay. Farther downstream the disturbance flow occupies the whole pipe, although the base flow is mostly inviscid in the core. The transient growth and subsequent viscous decay are confined in the entrance region, i.e. where the base flow has not reached the fully developed Poiseuille profile. Increasing the Reynolds number and decreasing the frequency causes more intense perturbations, whereas small azimuthal wavelengths and radial characteristic length scales intensify the viscous dissipation of the disturbance. The azimuthal wavelength that causes the maximum growth is found. The velocity profiles are compared successfully with available experimental data and the theoretical results are helpful to interpret the only direct numerical dataset of a disturbed pipe-entry flow.

Computerized Model of Transition in Circular Pipe Flows: Part 1 — Experimental Definition of the Problem

1999 ◽  
Author(s):  
Hidesada Kanda
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Critical Reynolds Number ◽  
Natural Disturbance ◽  
Reynolds Numbers ◽  
Entrance Region ◽  
Circular Pipe ◽  
Experimental Investigations ◽  
Circular Pipes ◽  
Definition Of

Abstract A conceptual model was constructed for the problem of determining in circular pipes the conditions under which the transition from laminar to turbulent flow occurs, so that it becomes possible to calculate the minimum critical Reynolds number. Up until now this problem has been investigated by stability theory with disturbances at the pipe inlet. However, the minimum critical Reynolds number has not yet been obtained theoretically. Hence, the author took up the problem directly from many previous experimental investigations and found that (i) plots of the transition length versus the Reynolds number show that the transition occurs in the entrance region under the condition of a natural disturbance, and (ii) plots of the critical Reynolds number versus the ratio of bellmouth diameter to the pipe diamter show that with larger shapes of bellmouths, laminar flow will persist to higher Reynolds numbers. The problem is thus defined clearly as: Under the condition of an ordinary disturbance, the transition from laminar to turbulent flow occurs in the entrance region of a straight circular pipe, then the Reynolds number takes a minimum value of about 2000.

Entrance region flow of polymer melts

AIChE Journal ◽  
1971 ◽  
Vol 17 (6) ◽  
pp. 1480-1485 ◽  
Author(s):  
Chang Dae Han
Keyword(s):  
Polymer Melts ◽  
Entrance Region ◽  
Region Flow

scholarly journals Laminar Swirling Flow in the Entrance Region of a Circular Pipe

1971 ◽  
Vol 14 (73) ◽  
pp. 659-670 ◽  
Author(s):  
Masaru KIYA ◽  
Shoichiro FUKUSAKO ◽  
Mikio ARIE
Keyword(s):  
Swirling Flow ◽  
Entrance Region ◽  
Circular Pipe

Variable viscosity entrance-region flow of non-newtonian liquids

1970 ◽  
Vol 13 (5) ◽  
pp. 901-909 ◽  
Author(s):  
A.A Mckillop ◽  
J.C Harper ◽  
H.J Bader ◽  
A.Y Korayem
Keyword(s):  
Variable Viscosity ◽  
Entrance Region ◽  
Region Flow ◽  
Newtonian Liquids
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