scholarly journals Asymmetric natural convection flow in three dimensional attic space

2019 ◽  
Author(s):  
Cui Huimin ◽  
Xu Feng ◽  
C. Saha Suvash ◽  
Liu Qingkuan
Keyword(s):  
Natural Convection ◽  
Three Dimensional ◽  
Convection Flow ◽  
Natural Convection Flow

Numerical Simulations of an Unsteady Confined Natural Convection Flow

2009 ◽  
Author(s):  
Gillian Leplat ◽  
Emmanuel Laroche ◽  
Philippe Reulet ◽  
Pierre Millan
Keyword(s):  
Natural Convection ◽  
Rayleigh Number ◽  
Large Scale ◽  
Critical Rayleigh Number ◽  
Three Dimensional ◽  
High Amplitude ◽  
Joint Fluid ◽  
Convection Flow ◽  
Two Dimensional ◽  
Natural Convection Flow

A two-dimensional numerical analysis of a laminar natural convection flow within an air-filled enclosure is proposed in this paper from an unstable configuration previously studied experimentally. The flow is driven by a heated square-section cylinder located at the center of a square-section enclosure. Instabilities are observed for an aspect ratio (height of the cylinder over the height of the cavity) of 0.4 and cause the flow to turn into a three-dimensional and unsteady regime characterized by a symmetry breaking and large scale high amplitude flappings around the cylinder. The multi-physic computational software CEDRE, developed at the ONERA, is used to study this unstable behavior and a time-dependent compressible flow solver is used to perform the two-dimensional simulations under the low Mach number approximation, corresponding to the mid-depth cross-section of the enclosure from the experimental configuration. The first results on the investigation of the first unstable modes confirm the onset of the instabilities at the Rayleigh number of the experiment with asymmetrical motions of the fluid around the cylinder. Further analyses highlight the critical Rayleigh number that defines the instability threshold of the first bifurcation which origin and nature could have been identified. Finally, joint fluid-solid simulations are performed to determine more precisely the role of boundary conditions in the onset of instabilities.

Flow Structure with Natural Convection in Inclined Air-Filled Enclosures

1981 ◽  
Vol 103 (3) ◽  
pp. 535-539 ◽  
Author(s):  
S. J. M. Linthorst ◽  
W. M. M. Schinkel ◽  
C. J. Hoogendoorn
Keyword(s):  
Natural Convection ◽  
Three Dimensional ◽  
Side Wall ◽  
Stationary Flow ◽  
Flow Structures ◽  
Convection Flow ◽  
Nonstationary Flow ◽  
Three Dimensional Flow ◽  
Natural Convection Flow ◽  
Made In

Flow visualization observations are described for natural convection flow in rectangular inclined enclosures. Observations are made in air-filled enclosures of small and moderate aspect ratio (0.25 ⩽ Ax ⩽ 7), angles of inclination from 0 to 90 deg and Rayleigh number between 5 × 103 and 2.5 × 105. For the range of parameters considered we determined the transition from stationary to nonstationary flow and the transition from two-dimensional to three-dimensional flow. Also, the different stationary flow structures are described. In addition measurements of the velocity profile of the stationary flow have been performed by means of a laser doppler anemometer. Special attention has been given to the side wall boundary condition of the enclosure.

Three-Dimensional Instabilities of Natural Convection Flow in a Vertical Cylinder With Partially Heated Sidewall

2004 ◽  
Vol 126 (4) ◽  
pp. 586 ◽  
Author(s):  
A. Rubinov ◽  
V. Erenburg ◽  
A. Yu. Gelfgat ◽  
E. Kit ◽  
P. Z. Bar-Yoseph ◽  
...  
Keyword(s):  
Natural Convection ◽  
Three Dimensional ◽  
Vertical Cylinder ◽  
Convection Flow ◽  
Natural Convection Flow
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