Low Prandtl number convection in a rectangular cavity with longitudinal thermal gradient and transverse

1991 ◽  
Vol 34 (8) ◽  
pp. 2167-2173 ◽  
Author(s):  
Didier Thevenard ◽  
Hamda Ben Hadid
Keyword(s):  
Prandtl Number ◽  
Thermal Gradient ◽  
Rectangular Cavity

Natural convection flow in an open rectangular cavity with cold sidewalls and constant volumetric heat source

2011 ◽  
Vol 225 (5) ◽  
pp. 1191-1201 ◽  
Author(s):  
M Saleem ◽  
S Asghar ◽  
M A Hossain
Keyword(s):  
Natural Convection ◽  
Rayleigh Number ◽  
Finite Difference ◽  
Heat Source ◽  
Prandtl Number ◽  
Rectangular Cavity ◽  
Maximum Temperature ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Volumetric Heat Source

The transient two-dimensional natural convection flow of Newtonian fluid in an open rectangular cavity has been studied numerically. The flow is induced due to constant internal heat generation. The alternate direct implicit (ADI) finite difference, together with upwind finite-difference scheme and successive over relaxation method, are used to solve the non-dimensional equations numerically. Effects of Rayleigh number, Ra, Prandtl number, Pr, and cavity aspect ratio, A, on the flow patterns and isotherms as well as on the heat transfer rate are studied graphically. The maximum temperature induced due to the constant volumetric heat source is found with the increase in cavity width, and to decrease with the increase in Prandtl number and Rayleigh number. The numerical model employed here is found to be in good agreement with the previous work.

Fission Gas Bubbles in Fractured UO2

1968 ◽  
Vol 26 ◽  
pp. 286-287
Author(s):  
O. M. Katz
Keyword(s):  
Electron Microscopy ◽  
Thermal Gradient ◽  
Gas Bubbles ◽  
Inert Gas ◽  
Thermal Gradients ◽  
Fission Gas ◽  
Beam Heating ◽  
Limited Application ◽  
Bubble Characteristics ◽  
Electron Beam Heating

The swelling of irradiated UO2 has been attributed to the migration and agglomeration of fission gas bubbles in a thermal gradient. High temperatures and thermal gradients obtained by electron beam heating simulate reactor behavior and lead to the postulation of swelling mechanisms. Although electron microscopy studies have been reported on UO2, two experimental procedures have limited application of the results: irradiation was achieved either with a stream of inert gas ions without fission or at depletions less than 2 x 1020 fissions/cm3 (∼3/4 at % burnup). This study was not limited either of these conditions and reports on the bubble characteristics observed by transmission and fractographic electron microscopy in high density (96% theoretical) UO2 irradiated between 3.5 and 31.3 x 1020 fissions/cm3 at temperatures below l600°F. Preliminary results from replicas of the as-polished and etched surfaces of these samples were published.

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