FLOW REVERSAL IN MIXED CONVECTION IN VERTICAL CONCENTRIC ANNULI

An experimental investigation of opposing mixed convection in an inclined pipe has been conducted. Dye injection reveals the existence of flow reversal regions. There is an optimal tilt angle that yields maximum flow reversal length. Flow reversals are seen to cause early transition to turbulence. Temperature profiles are measured across the tube cross section near the entrance to the heated section, and show the effect of tube inclination. Temperature measurements exhibit periodic behavior in the flow reversal region under some conditions, generally characterized by low tilt angle and moderate to high Reynolds and Grashof numbers. Flow visualization indicates that this periodic behavior is due to the intermittent breakdown of the flow reversal region.

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MHD Mixed Convection Micropolar Fluid Flow through a Rectangular Duct

Mathematical Problems in Engineering ◽

10.1155/2018/9840862 ◽

2018 ◽

Vol 2018 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Mekonnen Shiferaw Ayano ◽

Stephen T. Sikwila ◽

Stanford Shateyi

Keyword(s):

Magnetic Field ◽

Differential Equations ◽

Mixed Convection ◽

Applied Magnetic Field ◽

Flow Reversal ◽

Convection Flow ◽

Temperature Profiles ◽

Rectangular Duct ◽

Micropolar Fluid Flow ◽

Flow Through

Mixed convection flow through a rectangular duct with at least one of the sides of the walls of the rectangle being isothermal under the influence of transversely applied magnetic field has been analyzed numerically in this study. The governing differential equations of the problem have been transformed into a system of nondimensional differential equations and then solved numerically. The dimensionless velocity, microrotation components, and temperature profiles are displayed graphically showing the effects of various values of the parameters present in the problem. The results showed that the flow field is notably influenced by the considered parameters. It is found that increasing the aspect ratio increases flow reversal, commencement of the flow reversal is observed after some critical value, and the applied magnetic field increases the flow reversal in addition to flow retardation. The microrotation components flow in opposite direction; also it is found that one component of the microrotation will show no rotational effect around the center of the duct.

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Flow Reversal of Fully Developed Mixed Convection in a Vertical Channel with Chemical Reaction

International Journal of Chemical Engineering ◽

10.1155/2013/310273 ◽

2013 ◽

Vol 2013 ◽

pp. 1-4 ◽

Cited By ~ 3

Author(s):

Habibis Saleh ◽

Ishak Hashim ◽

Sri Basriati

Keyword(s):

Mixed Convection ◽

Chemical Reaction ◽

Buoyancy Force ◽

Vertical Channel ◽

Critical Values ◽

Flow Reversal ◽

Governing Equations ◽

Reversed Flow ◽

Exothermic Chemical Reaction

The present analysis is concerned with the criteria for the onset of flow reversal of the fully developed mixed convection in a vertical channel under the effect of the chemical reaction. The governing equations and the critical values of the buoyancy force are solved and calculated numerically via MAPLE. Parameter zones for the occurrence of reversed flow are presented. The exothermic chemical reaction is found to enhance the flow reversal and made flow reversal possible for symmetrical walls temperature.

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