Geometric phase, effective conductivity enhancement, and invisibility cloak in thermal convection-conduction

Author(s):  
Liujun Xu ◽  
Jun Wang ◽  
Gaole Dai ◽  
Shuai Yang ◽  
Fubao Yang ◽  
...  
1987 ◽  
Vol 109 (3) ◽  
pp. 775-781 ◽  
Author(s):  
J. R. Phillips ◽  
L. C. Chow ◽  
W. L. Grosshandler

Heat conduction through a metal cloth wick saturated with a fluid has been investigated. An apparatus used to measure thermal conductivity, in which the condition of wick packing geometry is carefully controlled, and the basic experimental procedure are described. Experimental results are presented and compared to a new mean-gap-conductance model based upon the wick geometry, and to the simple series model. The mean-gap-conductance model evaluates the effects of the mesh geometry, and with the addition of a correction term to account for three-dimensional effects and layer-to-layer contact, the effective conductivity can be accurately predicted. In addition, a correlation of the mean gap which directly includes three-dimensional and contact conductance effects is presented. The correlation predicts the data within 10 percent whereas the series model may be more than 40 percent in error. From a parametric study using the new model, theoretical limits on the maximum and minimum conductivity enhancement have been determined as a function of geometric parameters. The implications of the research on heat pipe wick design are discussed.


2020 ◽  
Vol 10 (3) ◽  
pp. 739 ◽  
Author(s):  
Nikolaos P. Karagiannakis ◽  
Nadia Bali ◽  
Eugene D. Skouras ◽  
Vasilis N. Burganos

A new meshless numerical approach for studying heat conduction in particulate systems was developed that allows the efficient computation of the temperature distribution and the effective thermal conductivity in particle aggregates. The incorporation of the discretization-corrected particle strength exchange operator in meshless local Petrov–Galerkin calculations is suggested here, which was shown to perform better than previously tested trial functions, regarding the speed of convergence and accuracy. Moreover, an automated algorithm for node refinement was developed, which avoids the necessity for user intervention. This was quite important in the study of particle aggregates due to the appearance of multiple points of contact between particles. An alternative approach for interpolation is also presented, that increased the stability of the methods and reduced the computational cost. Test case models, commercial computational fluid dynamics software, and experimental data were used for validation. Heat transport in various aggregate morphologies was also studied using sophisticated aggregation models, in order to quantify the effect of aggregate fractal dimension on the nanofluid conductivity, targeting eventually the optimization of heat transfer applications. A trend of effective conductivity enhancement upon reduction of the fractal dimension of the aggregate was noted.


2009 ◽  
Vol E92-C (12) ◽  
pp. 1504-1511 ◽  
Author(s):  
Thi Huong TRAN ◽  
Yuanfeng SHE ◽  
Jiro HIROKAWA ◽  
Kimio SAKURAI ◽  
Yoshinori KOGAMI ◽  
...  

2018 ◽  
Author(s):  
Takuma Ohtaki ◽  
Maho Mitsuo ◽  
Takayuki Terauchi ◽  
Hiroshi Iguchi ◽  
Keiko Fujioka ◽  
...  

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