APPLICABILITY OF THE SECOND MOMENT CLOSURE MODELS FOR TURBULENT HEAT FLUX OF THE TURBULENT NATURAL CONVECTION IN A CONFINED CAVITY

2018 ◽  
Author(s):  
Seokwon Whang ◽  
Hyun Sun Park ◽  
Moo Hwan Kim
Keyword(s):  
Heat Flux ◽  
Natural Convection ◽  
Turbulent Heat Flux ◽  
Moment Closure ◽  
Turbulent Heat ◽  
Second Moment ◽  
Turbulent Natural Convection ◽  
Closure Models ◽  
Second Moment Closure

Convective Heat Transfer in Wall-Bounded Flows Affected by Severe Fluid Properties Variation: A Second-Moment Closure Study

2010 ◽  
Author(s):  
S. Jakirlic´ ◽  
R. Jester-Zu¨rker
Keyword(s):  
Heat Flux ◽  
Dissipation Rate ◽  
Transport Equations ◽  
Moment Closure ◽  
Reference Database ◽  
Turbulent Heat ◽  
Second Moment ◽  
Fluid Properties ◽  
Second Moment Closure ◽  
Near Wall

Different flow configurations subjected to increasingly enhanced wall heating were selected to be computationally investigated by means of a differential, near-wall second-moment closure model based on the solution of transport equations for second moments of the fluctuating velocities and temperature, ui″uj″͠ and ui″θ͠ respectively. Both Reynolds stress model and heat flux model represent wall-topography free formulations with quadratic pressure-strain term and pressure-temperature-gradient correlation. The transport equations for the turbulent stress tensor and the turbulent heat flux are solved in conjunction with the equation governing a new scale supplying variable, so-called “homogeneous” dissipation rate, Jakirlic and Hanjalic (2002). Such an approach offers a number of important advantages: proper near-wall shape of the dissipation rate profile was obtained without introducing any additional term and the correct asymptotic behaviour of the stress dissipation components by approaching the solid wall is fulfilled automatically without necessity for any wall geometry-related parameter. The configurations considered include fully-developed and developing flows in channel (without and with a sudden expansion) and pipe in conjunction with the scalar transport under conditions of variable fluid properties for which an extensive experimental and numerical (DNS and LES) reference database exists.

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