C221 Turbulent Heat Transport for Thermal Mixing of Hot and Cold Flows in T-junction

2005 ◽  
Vol 2005 (0) ◽  
pp. 365-366
Author(s):  
Hiroki Goto ◽  
Hideo Asano ◽  
Masafumi Hirota ◽  
Hiroshi Nakayama ◽  
Shunsaku Hirayama
Keyword(s):  
Heat Transport ◽  
Turbulent Heat ◽  
Thermal Mixing

Control of Turbulent Transport: Less Friction and More Heat Transfer

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Nobuhide Kasagi ◽  
Yosuke Hasegawa ◽  
Koji Fukagata ◽  
Kaoru Iwamoto
Keyword(s):  
Heat Transfer ◽  
Heat Transport ◽  
Turbulent Transport ◽  
Scalar Fields ◽  
Wall Friction ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Control Input ◽  
Divergence Free Vector ◽  
Wide Range

Because of the importance of fundamental knowledge on turbulent heat transfer for further decreasing entropy production and improving efficiency in various thermofluid systems, we revisit a classical issue whether enhancing heat transfer is possible with skin friction reduced or at least not increased as much as heat transfer. The answer that numerous previous studies suggest is quite pessimistic because the analogy concept of momentum and heat transport holds well in a wide range of flows. Nevertheless, the recent progress in analyzing turbulence mechanics and designing turbulence control offers a chance to develop a scheme for dissimilar momentum and heat transport. By reexamining the governing equations and boundary conditions for convective heat transfer, the basic strategies for achieving dissimilar control in turbulent flow are generally classified into two groups, i.e., one for the averaged quantities and the other for the fluctuating turbulent components. As a result, two different approaches are discussed presently. First, under three typical heating conditions, the contribution of turbulent transport to wall friction and heat transfer is mathematically formulated, and it is shown that the difference in how the local turbulent transport of momentum and that of heat contribute to the friction and heat transfer coefficients is a key to answer whether the dissimilar control is feasible. Such control is likely to be achieved when the weight distributions for the stress and flux in the derived relationships are different. Second, we introduce a more general methodology, i.e., the optimal control theory. The Fréchet differentials obtained clearly show that the responses of velocity and scalar fields to a given control input are quite different due to the fact that the velocity is a divergence-free vector, while the temperature is a conservative scalar. By exploiting this inherent difference, the dissimilar control can be achieved even in flows where the averaged momentum and heat transport equations have the same form.

Coherent motions and heat transfer in a wall turbulent shear flow

1995 ◽  
Vol 305 ◽  
pp. 127-157 ◽  
Author(s):  
Y. Nagano ◽  
M. Tagawa
Keyword(s):  
Heat Transfer ◽  
Heat Transport ◽  
Phase Relationship ◽  
Transport Processes ◽  
Wall Turbulence ◽  
Ar Model ◽  
Turbulent Heat Transfer ◽  
Good Time ◽  
Turbulent Shear ◽  
Turbulent Heat

In wall turbulence, it is widely accepted that the coherent motions determine the essential features of turbulent transport phenomena. In the present study, we have refined a trajectory-based detection algorithm for coherent motions and have investigated the relationship between coherent motions and scalar (heat) transfer from a structural point of view, i. e. trajectory analysis of the VITA heat transfer events, extraction of key flow modules and the relevant heat transport, and the prediction of passive scalar transfer by means of an autoregressive (AR) model. As a result, it is shown that the phase relationship of fluctuating velocity components dominates the essential characteristics of the transport processes of heat and momentum in wall turbulence and there exist distinct differences in individual correspondence between the coherent motions and heat transport processes, neither of which can be revealed by the widely used VITA technique. Also, the AR model is shown to provide good time-series predictions for turbulent heat transfer associated with coherent structures near the wall.

scholarly journals Effect of self-generated zonal flows on turbulent heat transport in a tokamak plasma

2005 ◽  
Vol 7 ◽  
pp. 203-213
Author(s):  
G L Falchetto ◽  
X Garbet ◽  
Ph Ghendrih ◽  
M Ottaviani ◽  
Y Sarazin
Keyword(s):  
Heat Transport ◽  
Tokamak Plasma ◽  
Turbulent Heat ◽  
Zonal Flows

Turbulent heat transport in TOKAM3X edge plasma simulations

2018 ◽  
Vol 58 (6-8) ◽  
pp. 484-489 ◽  
Author(s):  
Camille Baudoin ◽  
Patrick Tamain ◽  
Hugo Bufferand ◽  
Guido Ciraolo ◽  
Nicolas Fedorczak ◽  
...  
Keyword(s):  
Heat Transport ◽  
Edge Plasma ◽  
Turbulent Heat ◽  
Plasma Simulations

On Turbulent Heat Transport in Rotating Convective Zones

1982 ◽  
Vol 303 (5) ◽  
pp. 293-303 ◽  
Author(s):  
G. Rüdiger
Keyword(s):  
Heat Transport ◽  
Turbulent Heat
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