Negatively buoyant flow along vertical cylinders at high Rayleigh numbers

1990 ◽  
Author(s):  
R. AHMAD ◽  
E. MATHIAS ◽  
S. BORAAS
Keyword(s):  
Buoyant Flow ◽  
Vertical Cylinders ◽  
Rayleigh Numbers ◽  
Negatively Buoyant

Negatively Buoyant Flow Along Vertical Cylinders at High Rayleigh Numbers

1992 ◽  
Vol 13 (2) ◽  
pp. 89-103 ◽  
Author(s):  
R. A. AHMAD ◽  
E. C. MATHIAS ◽  
S. BORAAS
Keyword(s):  
Buoyant Flow ◽  
Vertical Cylinders ◽  
Rayleigh Numbers ◽  
Negatively Buoyant

Negatively Buoyant Plume Flow in a Baffled Heat Exchanger

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Sandra K. S. Boetcher ◽  
F. A. Kulacki ◽  
Jane H. Davidson
Keyword(s):  
Heat Exchanger ◽  
Effective Width ◽  
Two Dimensional ◽  
Buoyant Plume ◽  
Fully Developed Flow ◽  
Buoyant Flow ◽  
Thermal Stores ◽  
Plume Flow ◽  
Rayleigh Numbers ◽  
Negatively Buoyant

A numerical simulation of transient two-dimensional negatively buoyant flow into a straight baffle situated below an isothermal circular cylinder in an initially isothermal enclosure is presented for both an adiabatic and a highly conducting baffle for Rayleigh numbers from 106 to 107. Results show the effects of baffle offset, width, and length on the point where viscous flow develops and on velocity profiles within the baffle. Results are interpreted to guide the design of straight baffles to reduce destruction of stratification in thermal stores using an immersed heat exchanger. The preferred geometry is a low-conductivity baffle of width equal to the effective width of the heat exchanger and 15 or more cylinder diameters in length to ensure nearly fully developed flow at the baffle outlet.

Buoyant Flow and Heat Transfer in a Conducting Baffle

2008 ◽  
Author(s):  
S. K. S. Boetcher ◽  
F. A. Kulacki
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Quasi Steady State ◽  
Two Dimensional ◽  
Buoyant Flow ◽  
Transfer Rates ◽  
Flow And Heat Transfer ◽  
Rayleigh Numbers ◽  
Negatively Buoyant ◽  
Surrounding Fluid

A numerical simulation of transient two-dimensional negatively buoyant flow into a straight baffle situated below an isothermal circular cylinder is performed. Both an adiabatic and a highly conducting baffle are considered over a range of Rayleigh numbers, 106 < RaD < 107. During the quasi-steady-state period, the surrounding fluid is effectively considered infinite in extent and at constant temperature. It is found that in general, the conducting baffle is at a disadvantage in maintaining a short attachment length which is needed to optimally slow the flow to prevent mixing. Qualitative flow fields are shown and heat transfer rates to the cylinder are calculated at the quasi-steady state.

Negatively Buoyant Flow in a Diverging Channel. I: Flow Regimes

1987 ◽  
Vol 113 (6) ◽  
pp. 716-730 ◽  
Author(s):  
Thomas R. Johnson ◽  
Gerard J. Farrell ◽  
Christopher R. Ellis ◽  
Heinz G. Stefan
Keyword(s):  
Flow Regimes ◽  
Buoyant Flow ◽  
Diverging Channel ◽  
Negatively Buoyant

Negatively Buoyant Plume Flow in a Baffle

2008 ◽  
Author(s):  
S. K. S. Boetcher ◽  
F. A. Kulacki
Keyword(s):  
Heat Transfer ◽  
Transfer Rate ◽  
Two Dimensional ◽  
Buoyant Plume ◽  
Buoyant Flow ◽  
Transfer Rates ◽  
Offset Distance ◽  
Plume Flow ◽  
Negatively Buoyant ◽  
Surrounding Fluid

Transient two-dimensional negatively buoyant flow into a straight adiabatic baffle beneath an isothermal circular cylinder is numerically simulated. The surrounding fluid is considered infinite in extent and at constant temperature. Governing parameters are the baffle width and the offset of the entrance of the baffle beneath the center of the cylinder. Overall characteristics of the flow and entrainment of the surrounding fluid are found to be dependent on the baffle offset; however, the attachment length of the flow to the baffle wall is relatively insensitive to the offset. Heat transfer rates to the cylinder are calculated for various times for various baffle offsets. There is a weak dependence on baffle-offset distance with heat transfer rate.

Effect of Surface Radiation on Free Convection in Vertical Cylinders Partially Annular

2018 ◽  
Vol 389 ◽  
pp. 36-49
Author(s):  
Belkacem Ould Said ◽  
Mohamed Amine Medebber ◽  
Nourddine Retiel
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Radiation Heat Transfer ◽  
Surface Radiation ◽  
Navier Stokes ◽  
Discrete Ordinates ◽  
Energy Equations ◽  
Vertical Cylinders ◽  
Rayleigh Numbers ◽  
Emissivity Coefficient

The coupled of free convection with surface radiation in an annular region of two concentric vertical cylinders filled with air has been numerically investigated. The steady-state continuity, Navier–Stokes and energy equations were carried out by the finite volume method, and the Discrete Ordinates Method (DOM) was used to solve the radiative heat transfer equation (RTE). The computations have been performed for 103 ≤Ra≤ 106, with the emissivity coefficient of all the walls varying between 0 and 1. The influence of the both, Rayleigh numbers and emissivity coefficient of the wall for fixed height ratio X=0.5 on natural convection and radiation heat transfer in enclosure have been solved. The result shows that surface radiation significantly altered the temperature distribution and the flow patterns, especially at higher Rayleigh numbers. The average Nusselt number has also been discussed for different emissivity through the enclosure.

Sign in / Sign up

Export Citation Format

Share Document