Chaotic mixing and heat transfer in time-periodic 3-D Stokes flows

2002 ◽  
Author(s):  
Antonio Jose Silveiro Rodrigo ◽  
Jose Paulo Barbosa Mota ◽  
Esteban Saatdjian
Keyword(s):  
Heat Transfer ◽  
Chaotic Mixing ◽  
Stokes Flows ◽  
Time Periodic

Chaotic Mixing: A Sure Way for Optimal Thermal Conditions?

2010 ◽  
Author(s):  
M. F. M. Speetjens
Keyword(s):  
Heat Transfer ◽  
Thermal State ◽  
Electronics Cooling ◽  
Thermal Conditions ◽  
Laminar Flows ◽  
Chaotic Mixing ◽  
Asymptotic State ◽  
Driven Cavity ◽  
Time Periodic

Chaotic fluid mixing is generally considered to enhance fluid-wall heat transfer and thermal homogenisation in laminar flows. However, this essentially concerns the transient stage towards a fully-developed (thermally-homogeneous) asymptotic state and then specifically for high Pe´clet numbers Pe (convective heat transfer dominates). The role of chaos in the asymptotic state at lower Pe, relevant to continuously-operating compact devices as, for instance, micro-electronics cooling systems, remains largely unexplored to date. The present study seeks to gain first insight into this matter by the analysis of a representative model problem: heat transfer in the 2D time-periodic lid-driven cavity flow induced via non-adiabatic walls. The asymptotic time-periodic thermal state is investigated in terms of both the temperature field and the thermal transport routes. This combined Eulerian-Lagrangian approach enables fundamental investigation of the connection between heat transfer and chaotic mixing and its ramifications for temperature distributions and heat-transfer rates. The analysis exposes a very different role of chaos in that its effectiveness for thermal homogenisation and heat-transfer enhancement is in low-Pe asymptotic states marginal at best. Here chaos may in fact locally amplify temperature fluctuations and thus hamper instead of promote thermal homogeneity. These findings reveal that optimal thermal conditions are not always automatic with chaotic mixing and may depend on a more delicate interplay between flow and heat-transfer mechanisms.

Chaotic advection and heat transfer enhancement in Stokes flows

2002 ◽  
Author(s):  
A. Lefevre ◽  
Jose Paulo Barbosa Mota ◽  
Antonio Jose Silveiro Rodrigo ◽  
Esteban Saatdjian
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Chaotic Advection ◽  
Transfer Enhancement ◽  
Stokes Flows

Effects of a centered conducting body on natural convection of non-Newtonian fluid in a square enclosure with time-periodic temperature distribution

2020 ◽  
Author(s):  
Peixin Ye ◽  
Dinggen Li ◽  
Zihao Yu ◽  
Haifeng Zhang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Capacity ◽  
Transient Heat Transfer ◽  
Thermal Conductivity Ratio ◽  
Conductivity Ratio ◽  
Transfer Ratio ◽  
Periodic Temperature ◽  
Power Law Index ◽  
Time Periodic

In this paper, a modified lattice Boltzmann model that incorporates the effect of heat capacity is adopted to study the effects of a centered conducting body on natural convection of non-Newtonian fluid in a square cavity with time-periodic temperature distribution. The effects of power-law index, Rayleigh number, heat capacity ratio, thermal conductivity ratio, body size, temperature pulsating period and the temperature pulsating amplitude on fluid flow and heat transfer are analyzed in detail. The results showed that the increase of Rayleigh number and thermal conductivity ratio as well as the decrease of power-law index can strengthen both transient and global heat transfer, while the increase of heat capacitance of fluid to the solid wall can only enhance the transient heat transfer, and has little effect on the overall heat transfer. Further, the increase of body size will reduce both the transient heat transfer ratio and the overall heat transfer ratio. In addition, the decrease of temperature pulsating period can enhance the transient heat transfer, but it will slightly weaken the overall heat transfer. Finally, the results show that both the transient and the overall heat transfer ratio are increased with the increase of temperature pulsating amplitude.

Heat Transfer Characteristics of Baffled Channel Flow

2011 ◽  
Author(s):  
Changwoo Kang ◽  
Kyung-Soo Yang
Keyword(s):  
Heat Transfer ◽  
Channel Flow ◽  
Large Scale ◽  
Heat Removal ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow Heat ◽  
Two Parameters ◽  
Time Periodic

Heat transfer characteristics of baffled channel flow, where thin baffles are mounted on both channel walls periodically in the direction of the main flow, have been numerically investigated in a laminar range. In baffled channel flow, heat transfer characteristics are significantly affected by large-scale vortices generated due to flow separation at the tips of the baffles. In this investigation, a parametric study has been carried out to identify the optimal configuration of the baffles to achieve the most efficient heat removal from the channel walls. Two key parameters are considered, namely baffle interval (L) and Reynolds number (Re). We elucidate the role of the primary instability, a Hopf bifurcation from steady to a time-periodic flow, in the convective heat transfer in baffled channel flow. We also propose a contour diagram (“map”) of averaged Nusselt number on the channel walls as a function of the two parameters. The results shed light on understanding and controlling heat transfer mechanism in a finned heat exchanger, being quite beneficial to its design.

Free surface Nvier-Stokes flows with simultaneous heat transfer and solidification/melting

1996 ◽  
Vol 6 (1) ◽  
pp. 295-308 ◽  
Author(s):  
K. A. Pericleous ◽  
M. Cross ◽  
G. Moran ◽  
P. Chow ◽  
K. S. Chan
Keyword(s):  
Heat Transfer ◽  
Free Surface ◽  
Stokes Flows ◽  
Heat Transfer And Solidification ◽  
Simultaneous Heat
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