Some cases of two-dimensional duct flow of a fluid with internal rotation

Direct numerical simulations and linear stability analysis are carried out to study mixed convection in a horizontal duct with constant-rate heating applied at the bottom and an imposed transverse horizontal magnetic field. A two-dimensional approximation corresponding to the asymptotic limit of a very strong magnetic field effect is validated and applied, together with full three-dimensional analysis, to investigate the flow's behaviour in the previously unexplored range of control parameters corresponding to typical conditions of a liquid metal blanket of a nuclear fusion reactor (Hartmann numbers up to $10^4$ and Grashof numbers up to $10^{10}$ ). It is found that the instability to quasi-two-dimensional rolls parallel to the magnetic field discovered at smaller Hartmann and Grashof numbers in earlier studies also occurs in this parameter range. Transport of the rolls by the mean flow leads to magnetoconvective temperature fluctuations of exceptionally high amplitudes. It is also demonstrated that quasi-two-dimensional structure of flows at very high Hartmann numbers does not guarantee accuracy of the classical two-dimensional approximation. The accuracy deteriorates at the highest Grashof numbers considered in the study.

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Unsteady Laminar Duct Flow With a Given Volume Flow Rate Variation

Journal of Applied Mechanics ◽

10.1115/1.1304843 ◽

1999 ◽

Vol 67 (2) ◽

pp. 274-281 ◽

Cited By ~ 36

Author(s):

D. Das ◽

J. H. Arakeri

Keyword(s):

Cross Section ◽

Flow Rate ◽

Volume Flow Rate ◽

Circular Cross Section ◽

Volume Flow ◽

Rate Variation ◽

Two Dimensional ◽

Duct Flow ◽

Fully Developed Flow ◽

Gradient Variation

In this paper we give a procedure to obtain analytical solutions for unsteady laminar flow in an infinitely long pipe with circular cross section, and in an infinitely long two-dimensional channel, created by an arbitrary but given volume flow rate with time. In the literature, solutions have been reported when the pressure gradient variation with time is prescribed but not when the volume flow rate variation is. We present some examples: (a) the flow rate has a trapezoidal variation with time, (b) impulsively started flow, (c) fully developed flow in a pipe is impulsively blocked, and (d) starting from rest the volume flow rate oscillates sinusoidally. [S0021-8936(00)01702-5]

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Visualization and Analysis of Flow in an Offset Channel

Journal of Heat Transfer ◽

10.1115/1.2911888 ◽

1992 ◽

Vol 114 (4) ◽

pp. 819-826 ◽

Cited By ~ 3

Author(s):

J. A. Walter ◽

C.-J. Chen

Keyword(s):

Reynolds Number ◽

Velocity Field ◽

Nuclear Power ◽

Flow Direction ◽

Symmetry Plane ◽

Two Dimensional ◽

Plant Design ◽

Duct Flow ◽

Inlet Channel ◽

Cross Sectional

This paper investigates flow characteristics for a benchmark experiment that is important for thermal hydraulic phenomena in nuclear power plant design. The flow visualization experiment is carried out for flow in a rectangular offset channel covering both the laminar and turbulent flow regimes. The Reynolds number, based on the inlet velocity and the height of the inlet channel, ranges from 25 to 4600. The offset channel is an idealized thermal hydraulic geometry. Duct flow expands in a rectangular chamber and exits to a duct that is offset from the entrance duct. The offset geometry creates zones of recirculation for thermal-hydraulic mixing. Flow patterns are visualized by a laser light sheet in the symmetry plane of the primary flow direction and in three cross-sectional planes. A charge-coupled device (CCD) images the flow field, simplifying the experimental process and subsequent image analyses. The flow pattern and size of the recirculation zones change dramatically with Reynolds number until the flow is fully turbulent. While the velocity field itself is predominantly two dimensional, it is shown that the walls of the chamber produce a fully three-dimensional flow that could not be predicted properly by a two-dimensional calculation. Quantitative measurements of particle pathlines from several images are superimposed to give a composite view of the velocity field at one of the Reynolds numbers examined.

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Solar internal rotation and dynamo waves: A two-dimensional asymptotic solution in the convection zone

Journal of Astrophysics and Astronomy ◽

10.1007/bf02702428 ◽

2000 ◽

Vol 21 (3-4) ◽

pp. 379-380

Author(s):

Gaetano Belvedere ◽

Kirill Kuzanyan ◽

Dmitry Sokoloff

Keyword(s):

Asymptotic Solution ◽

Internal Rotation ◽

Convection Zone ◽

Two Dimensional ◽

Dynamo Waves

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Measured deposition of aerosol particles on a two-dimensional ribbed surface in a turbulent duct flow

Journal of Aerosol Science ◽

10.1016/s0021-8502(99)00021-x ◽

1999 ◽

Vol 30 (9) ◽

pp. 1201-1214 ◽

Cited By ~ 41

Author(s):

A.C.K Lai ◽

M.A Byrne ◽

A.J.H Goddard

Keyword(s):

Aerosol Particles ◽

Two Dimensional ◽

Duct Flow ◽

Turbulent Duct Flow

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Turbulent Flow Past a Surface-Mounted Two-Dimensional Rib

Journal of Fluids Engineering ◽

10.1115/1.2910261 ◽

1994 ◽

Vol 116 (2) ◽

pp. 238-246 ◽

Cited By ~ 46

Author(s):

S. Acharya ◽

S. Dutta ◽

T. A. Myrum ◽

R. S. Baker

Keyword(s):

Kinetic Energy ◽

Shear Layer ◽

High Speed ◽

Two Dimensional ◽

Duct Flow ◽

Core Flow ◽

The Core ◽

Separated Shear Layer ◽

Flow Past ◽

The Mean

The ability of the nonlinear k–ε turbulence model to predict the flow in a separated duct flow past a wall-mounted, two-dimensional rib was assessed through comparisons with the standard k–ε model and experimental results. Improved predictions of the streamwise turbulence intensity and the mean streamwise velocities near the high-speed edge of the separated shear layer and in the flow downstream of reattachment were obtained with the nonlinear model. More realistic predictions of the production and dissipation of the turbulent kinetic energy near reattachment were also obtained. Otherwise, the performance of the two models was comparable, with both models performing quite well in the core flow regions and close to reattachment and both models performing poorly in the separated and shear-layer regions close to the rib.

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