Design of Macro-rough Surface and Its Influence on Side Wall Heated Square Enclosure

Author(s):  
Ashwin Mahendra ◽  
Rajendran Senthil kumar
Author(s):  
Syeda Humaira Tasnim ◽  
Shohel Mahmud ◽  
Animesh Dutta

Natural convection through a porous layer heated from the side with internal flow obstructions have been investigated based on visualization of total energy flow via energy streamfunctions or energy streamlines. Energy streamline has been introduced previously by Mahmud and Fraser (2007, “Visualizing Energy Flows Through Energy Streamlines and Pathlines,” Int. J. Heat Mass Transfer, 50, pp. 3990–4002) as an alternate convection heat transfer energy visualization technique. Energy streamlines consider all forms of related energy; for example, thermal energy, potential energy, kinetic energy, electrical energy, magnetic energy, and chemical energy. A finite volume method has been employed to solve momentum and energy balance as well as postprocessing energy streamfunctions. A parametric study has been carried out using the following parameters: Rayleigh number (Ra) from 103 to 106, Darcy number (Da) from 10−4 to 10−3, dimensionless thin fin lengths (L) 0.25, 0.5, and 0.75, dimensionless positions (H) 0.25, 0.5, and 0.75 with Prandtl number (Pr) 0.7. One finding of the present study is that, adding an obstruction in a cavity is similar to reducing Da of the porous medium. Therefore, the average Nusselt number calculated on the hot wall of the cavity always degraded compared to the no obstruction case whenever a baffle is attached. Thus the attached horizontal obstruction adds some thermal insulation effect. This finding is important in double wall space filled with fiberglass insulation in contemporary buildings, where the side wall is reinforced on the inside with structural members.


2001 ◽  
Author(s):  
Patrick H. Oosthuizen ◽  
David Scott

Abstract Natural convective flew in a large square enclosure with a narrow rectangular enclosure mounted symmetrically on the upper surface of this main enclosure has been considered. The horizontal bottom and vertical side-walls of the main enclosure are assumed to be at a uniform high temperature and the vertical side-walls of the narrow top enclosure are assumed have a temperature that varies linearly with height above the main enclosure. The top horizontal wall of the upper enclosure is assumed to be adiabatic The situation consider is an approximate model of that which arises when measurements have to be made in a large enclosure containing a hot fluid and in which the measuring instrument is mounted in a small enclosure which is open at one end to the main tank and which has the instrument mounted at the opposite closed end. In order to ensure that the instrument is not exposed to a temperature that is above its operational limit, the walls of this small enclosure are cooled. Fluid properties have been assumed constant except for the density change with temperature that gives rise to the buoyancy forces, this being treated by means of the Boussinesq type approximation. The governing equations have been written in dimensionless form and the resultant dimensionless equations have been solved using a finite-element method. Results have been obtained for a Prandtl number of 0.7. The effects of Rayleigh number and dimensionless height and width of the top enclosure on the maximum temperature of the top adiabatic surface have been investigated. The results show that provided the aspect ratio of the upper enclosure is kept large, overheating of the upper adiabatic surface of the top enclosure is not likely to occur.


2014 ◽  
Vol 2014 ◽  
pp. 1-18 ◽  
Author(s):  
Sonam Singh ◽  
R. Bhargava

This paper presents a numerical study of natural convection within a wavy enclosure heated via corner heating. The considered enclosure is a square enclosure with left wavy side wall. The vertical wavy wall of the enclosure and both of the corner heaters are maintained at constant temperature,TcandTh, respectively, withTh>Tcwhile the remaining horizontal, bottom, top and side walls are insulated. A penalty element-free Galerkin approach with reduced gauss integration scheme for penalty terms is used to solve momentum and energy equations over the complex domain with wide range of parameters, namely, Rayleigh number (Ra), Prandtl number (Pr), and range of heaters in thex- andy-direction. Numerical results are represented in terms of isotherms, streamlines, and Nusselt number. It is observed that the rate of heat transfer depends to a great extent on the Rayleigh number, Prandtl number, length of the corner heaters and the shape of the heat transfer surface. The consistent performance of the adopted numerical procedure is verified by comparison of the results obtained through the present meshless technique with those existing in the literature.


2014 ◽  
Vol 134 (2) ◽  
pp. 20-25 ◽  
Author(s):  
Takanori Aono ◽  
Yasuhiro Yoshimura ◽  
Yoshinori Nakayama ◽  
Masatoshi Kanamaru
Keyword(s):  

2008 ◽  
Vol 128 (8) ◽  
pp. 325-330 ◽  
Author(s):  
Hiroaki Kawata ◽  
Junya Ishihara ◽  
Masayo Kayama ◽  
Masaaki Yasuda ◽  
Yoshihiko Hirai
Keyword(s):  

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