Application of a Higher Order GGDH Heat Flux Model to Three-Dimensional Turbulent U-Bend Duct Heat Transfer

2003 ◽  
Vol 125 (1) ◽  
pp. 200-203 ◽  
Author(s):  
K. Suga ◽  
M. Nagaoka and ◽  
N. Horinouchi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Higher Order ◽  
Moment Closure ◽  
Turbulent Heat ◽  
Generalized Gradient ◽  
Flux Model ◽  
Heat Flux Model

A higher order version of the generalized gradient diffusion hypothesis (HOGGDH) for turbulent heat flux is applied to predict heat transfer in a square-sectioned U-bend duct. The flow field turbulence models coupled with are a cubic nonlinear eddy viscosity model and a full second moment closure. Both of them are low Reynolds number turbulence models. The benefits of using the HOGGDH heat flux model are presented through the comparison with the standard GGDH.

scholarly journals Cattaneo–Christov Heat Flux Model for Three-Dimensional Rotating Flow of SWCNT and MWCNT Nanofluid with Darcy–Forchheimer Porous Medium Induced by a Linearly Stretchable Surface

Symmetry ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 331 ◽  
Author(s):  
Zahir Shah ◽  
Asifa Tassaddiq ◽  
Saeed Islam ◽  
A.M. Alklaibi ◽  
Ilyas Khan
Keyword(s):  
Heat Flux ◽  
Three Dimensional ◽  
Mass Motion ◽  
Physical Parameters ◽  
State Variables ◽  
Homotopy Analysis ◽  
Nanoparticles Concentration ◽  
Flux Model ◽  
Swcnts And Mwcnts ◽  
Heat Flux Model

In this paper we investigated the 3-D Magnetohydrodynamic (MHD) rotational nanofluid flow through a stretching surface. Carbon nanotubes (SWCNTs and MWCNTs) were used as nano-sized constituents, and water was used as a base fluid. The Cattaneo–Christov heat flux model was used for heat transport phenomenon. This arrangement had remarkable visual and electronic properties, such as strong elasticity, high updraft stability, and natural durability. The heat interchanging phenomenon was affected by updraft emission. The effects of nanoparticles such as Brownian motion and thermophoresis were also included in the study. By considering the conservation of mass, motion quantity, heat transfer, and nanoparticles concentration the whole phenomenon was modeled. The modeled equations were highly non-linear and were solved using homotopy analysis method (HAM). The effects of different parameters are described in tables and their impact on different state variables are displayed in graphs. Physical quantities like Sherwood number, Nusselt number, and skin friction are presented through tables with the variations of different physical parameters.

Use of Algebraic Heat Flux Models to Improve Heat Transfer Predictions for Supercritical Pressure Fluids

2016 ◽  
Author(s):  
Vera Papp ◽  
Andrea Pucciarelli ◽  
Medhat Sharabi ◽  
Walter Ambrosini
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Turbulent Heat Flux ◽  
Supercritical Pressure ◽  
Internal Diameter ◽  
Inlet Temperature ◽  
Turbulent Heat ◽  
Commercial Code ◽  
Simplifying Assumptions ◽  
Flux Model

This work proposes simulations of heat transfer under supercritical pressure conditions showing improvements with respect to previous works. This is obtained by the introduction of the Algebraic Heat Flux Model (AHFM) for evaluating the turbulent heat flux in turbulence production terms, using the in-house code THEMAT and the STAR-CCM+ code. The first code makes use of the AHFM also in the energy balance equations, while for the commercial code simplifying assumptions are considered in the implementations. Custom sets of parameters for every condition of inlet temperature and internal diameter are tuned in some cases, driven by the opinion that a single set of parameters cannot be suitable in every flow conditions, considering the complexity of the variables that concur in the heat transfer deterioration phenomenon. The AHFM model gives promising results with new sets of parameters in order to model the deterioration and the recovery phases because of its term related to the variance of temperature.

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