Laminar-Turbulent Transition in Pipeflow of Casson Model Fluids

Methanol-coal slurries are known to behave as homogeneous non-Newtonian suspensions. Darby has shown that the Casson and Bingham models reasonably describe the rheology of methanol-lignite slurries. Theoretical methods are available for predicting critical velocities for Bingham model slurries, but none exist for Casson model slurries. Theoretical equations and design curves are derived and presented for Casson model slurries. These are based upon a proven general theory for transition critical velocities. These results are the essential first phase of a coordinated theory-based design method for transitional and turbulent flow of methanol-coal slurries and any other slurries having Casson-model rheology.

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Common features between the Newtonian laminar–turbulent transition and the viscoelastic drag-reducing turbulence

Journal of Fluid Mechanics ◽

10.1017/jfm.2019.567 ◽

2019 ◽

Vol 877 ◽

pp. 405-428 ◽

Cited By ~ 8

Author(s):

Anselmo S. Pereira ◽

Roney L. Thompson ◽

Gilmar Mompean

Keyword(s):

Reynolds Number ◽

Turbulent Flow ◽

Drag Reduction ◽

Turbulent Flows ◽

Temporal Dynamics ◽

Homoclinic Orbits ◽

Theoretical Development ◽

Transitional Flows ◽

Turbulent Transition ◽

Laminar Turbulent Transition

The transition from laminar to turbulent flows has challenged the scientific community since the seminal work of Reynolds (Phil. Trans. R. Soc. Lond. A, vol. 174, 1883, pp. 935–982). Recently, experimental and numerical investigations on this matter have demonstrated that the spatio-temporal dynamics that are associated with transitional flows belong to the directed percolation class. In the present work, we explore the analysis of laminar–turbulent transition from the perspective of the recent theoretical development that concerns viscoelastic turbulence, i.e. the drag-reducing turbulent flow obtained from adding polymers to a Newtonian fluid. We found remarkable fingerprints of the variety of states that are present in both types of flows, as captured by a series of features that are known to be present in drag-reducing viscoelastic turbulence. In particular, when compared to a Newtonian fully turbulent flow, the universal nature of these flows includes: (i) the statistical dynamics of the alternation between active and hibernating turbulence; (ii) the weakening of elliptical and hyperbolic structures; (iii) the existence of high and low drag reduction regimes with the same boundary; (iv) the relative enhancement of the streamwise-normal stress; and (v) the slope of the energy spectrum decay with respect to the wavenumber. The maximum drag reduction profile was attained in a Newtonian flow with a Reynolds number near the boundary of the laminar regime and in a hibernating state. It is generally conjectured that, as the Reynolds number increases, the dynamics of the intermittency that characterises transitional flows migrate from a situation where heteroclinic connections between the upper and the lower branches of solutions are more frequent to another where homoclinic orbits around the upper solution become the general rule.

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Laminar-turbulent transition in a radial free liquid film flow. (3rd report. Velocity measurements on transition from laminar to turbulent flow).

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B ◽

10.1299/kikaib.54.361 ◽

1988 ◽

Vol 54 (498) ◽

pp. 361-366 ◽

Cited By ~ 2

Author(s):

Tsuneo AZUMA ◽

Naomasa MORISHIMA

Keyword(s):

Turbulent Flow ◽

Liquid Film ◽

Film Flow ◽

Velocity Measurements ◽

Turbulent Transition ◽

Free Liquid Film ◽

Liquid Film Flow ◽

Laminar Turbulent Transition

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Recent advances in theoretical methods for laminar-turbulent transition prediction

10.2514/6.1998-223 ◽

1998 ◽

Cited By ~ 8

Author(s):

D. Arnal ◽

G. Gasparian ◽

H. Salinas

Keyword(s):

Theoretical Methods ◽

Transition Prediction ◽

Turbulent Transition ◽

Recent Advances ◽

Laminar Turbulent Transition

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Simulation of a laminar-turbulent flow in three-dimensional aerodynamic configurations

Journal of Physics Conference Series ◽

10.1088/1742-6596/2057/1/012080 ◽

2021 ◽

Vol 2057 (1) ◽

pp. 012080

Author(s):

T V Poplavskaya ◽

A V Boiko ◽

K V Demyanko ◽

S V Kirilovskiy ◽

Y M Nechepurenko

Keyword(s):

Experimental Data ◽

Boundary Layer ◽

Turbulent Flow ◽

Three Dimensional ◽

Prolate Spheroid ◽

Turbulent Transition ◽

Good Agreement ◽

Laminar Turbulent Transition

Abstract The goal of the paper is to determine the position of the laminar-turbulent transition in the boundary layer of a prolate spheroid using the eN-method with the calibration of threshold N-factors. It is demonstrated that the predicted and experimental data on the laminarturbulent transition are in good agreement.

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