A hybrid LES/RANS approach using anisotropy-resolving algebraic turbulence models for predicting turbulent heat transfer

2007 ◽  
Vol 36 (5) ◽  
pp. 249-264 ◽  
Author(s):  
Minoru Inuzuka ◽  
Ken-Ichi Abe
Keyword(s):  
Heat Transfer ◽  
Turbulence Models ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat

Determination of Flow Characteristics and Turbulent Heat Transfer in a Ribbed Roughened Square Duct, Part 2: Numerical Simulations

2011 ◽  
Vol 110-116 ◽  
pp. 2364-2369
Author(s):  
Amin Etminan ◽  
H. Jafarizadeh ◽  
M. Moosavi ◽  
K. Akramian
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Square Duct ◽  
Optimized Model ◽  
Rsm Model

In the part 1 of this research, some useful turbulence models presented. In that part advantages of those turbulence models has been gathered. In the next, numerical details and procedure of solution are presented in details. By use of different turbulence models, it has been found that Spallart-Allmaras predicted the lowest value of heat transfer coefficient; in contrast, RSM1 has projected the more considerable results compared with other models; besides, it has been proven that the two-equation models prominently taken lesser time than RSM model. Eventually, the RNG2 model has been introduced as the optimized model of this research; moreover.

Turbulent Heat Transfer Computations for Rearward-Facing Steps and Sudden Pipe Expansions

1985 ◽  
Vol 107 (1) ◽  
pp. 70-76 ◽  
Author(s):  
A. M. Gooray ◽  
C. B. Watkins ◽  
Win Aung
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Dynamic ◽  
Turbulence Models ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Streamline Curvature ◽  
Recirculating Flow ◽  
Moderate Reynolds Number ◽  
Entire Flow

Results of numerical calculations for heat transfer in turbulent recirculating flow over two-dimensional, rearward-facing steps and sudden pipe expansions are presented. The turbulence models used in the calculation are the standard k – ε model and the low-Reynolds number version of this model. The k – ε models have been improved to account for the effects of streamline curvature and pressure-strain (scalar) interactions including wall damping. A sequence of two computational passes is performed to obtain optimal results over the entire flow field. The presented results consist of computed distributions of heat transfer coefficents for several Reynolds numbers, emphasizing the low-to-moderate Reynolds number regime. The heat transfer results also include correlations of Nusselt numnber for both side and bottom walls. The computed heat transfer results and typical computed fluid dynamic results are compared with available experimental data.

Prediction of Turbulent Heat Transfer and Fluid Flow in 2D Channels Roughened by Square and Deformed Ribs

2003 ◽  
Author(s):  
Rongguang Jia ◽  
Bengt Sunde´n
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Turbine Blades ◽  
Turbulence Models ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Turbine Cooling ◽  
Experimental Heat ◽  
Flow And Heat Transfer ◽  
Enhancing Heat Transfer

Introduction of roughness by ribs in flow passages is a popular method of enhancing heat transfer in the cooling passages, e.g., of turbine blades and combustors. It is essential to accurately predict the enhancement of heat transfer generated by the ribs to ensure good design decisions. In most of the studies square ribs have been considered, but in practice such ribs may appear rounded due to improper manufacturing or wear during operation. This study is focused on the effect of the rib deformations, based on computational fluid dynamics (CFD). One of the main difficulties in CFD is the reliable modeling of the underlying physics of the turbulence. This paper describes some recent efforts to validate and apply RANS-based models for predictions of turbulent flow and heat transfer in ribbed ducts, relevant to gas turbine cooling. The evaluated turbulence models include a basic low-Re k-ε model (AKN), and two promising higher order models: namely, the explicit algebraic stress model (EASM), and the V2F model. All these models are validated with available 2D experimental heat transfer and fluid flow data. Some conclusions are reached on their suitable application situations. The effect of the roundedness on heat transfer and fluid flow is presented in detail. Some possible improvements, i.e., of the deformed ribs, are proposed to suppress the hot spots, and/or to enhance the overall thermal and hydraulic performance.

scholarly journals A Logarithmic Turbulent Heat Transfer Model in Applications with Liquid Metals for PR = 0.01-0.025

2020 ◽  
Author(s):  
Roberto Da Vià ◽  
Sandro Manservisi ◽  
Valentina Giovacchini
Keyword(s):  
Heat Transfer ◽  
Turbulence Model ◽  
Liquid Metals ◽  
Turbulence Models ◽  
Turbulent Heat Flux ◽  
Turbulent Heat Transfer ◽  
Transfer Model ◽  
Turbulent Heat ◽  
Reynolds Analogy ◽  
Wide Range

The study of turbulent heat transfer in liquid metal flows has gained interest because of applications in several industrial fields. The common assumption of similarity between the dynamical and thermal turbulence, namely the Reynolds analogy, has been proven to be not valid for these fluids. Many methods have been proposed in order to overcome the difficulties encountered in a proper definition of the turbulent heat flux, such as global or local correlations for the turbulent Prandtl number or four parameter turbulence models. In this work we assess a four parameter logarithmic turbulence model for liquid metals based on RANS approach. Several simulation results considering fluids with Pr = 0.01 and Pr = 0.025 are reported in order to show the validity of this approach. The Kays turbulence model is also assessed and compared with integral heat transfer correlations for a wide range of Peclet numbers.

scholarly journals Rayeilgh number effect on the turbulent heat transfer within a parallelepiped cavity

2011 ◽  
Vol 15 (suppl. 2) ◽  
pp. 341-356 ◽  
Author(s):  
Mohamed Aksouh ◽  
Amina Mataoui ◽  
Nassim Seghouani ◽  
Zoubida Haddad
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Natural Convection ◽  
Low Reynolds Number ◽  
Turbulence Models ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Practical Applications ◽  
Low Reynolds

This purpose is about a three dimensional study of natural convection within cavities. This problem is receiving more and more research interest due to its practical applications in the engineering and the astrophysical research The turbulent natural convection of air in an enclosed tall cavity with high aspect ratio (AR=H/W=28.6) is examined numerically. Two cases of differential temperature have been considered between the lateral cavity plates corresponding, respectively, to the low and high Rayleigh numbers: Ra=8.6?105 and Ra=1.43?106 [1]. For these two cases, the flow is characterized by a turbulent low Reynolds number. This led us to improve the flow characteristics using two one point closure low-Reynolds number turbulence models: RNG k-e model and SST k-w model, derived from standard k-e model and standard k-w model, respectively. Both turbulence models have provided an excellent agreement with the experimental data. In order to choose the best model, the average Nusselt number is compared to the experiment and other numerical results. The vorticity components surfaces confirm that the flow can be considered two-dimensional with stretched vortex in the cavity core. Finally, a correlation between Nusselt number and Rayleigh number is obtained to predict the heat transfer characteristics.

Determination of Flow Characteristics and Turbulent Heat Transfer in a Ribbed Roughened Square Duct, Part 1: Turbulence Models

2011 ◽  
Vol 110-116 ◽  
pp. 2359-2363
Author(s):  
Amin Etminan ◽  
H. Jafarizadeh ◽  
M. Moosavi ◽  
K. Akramian
Keyword(s):  
Heat Transfer ◽  
Flow Structure ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Turbulent Model ◽  
Square Duct ◽  
Rans Models

Nowadays, many researchers works in fluid dynamics has been concentrated on determine the suitable turbulent model for better describing the flow structure and heat transfer characteristics in a specific problem, there are a lot of cases which are necessary about designation of an optimized turbulent model. In the present work, a ribbed roughened square duct has been investigated numerically. A two-dimensionally study has been done to evaluate the flow structure, heat transfer and computational efforts of seven turbulent RANS models, contemporaneously. In the Part 1 of this study turbulence models, which are used in these type of problems has been investigated. In the next, advantages of introduced turbulence models has been present and explained. The results of numerical simulations will be presented in the Part 2.

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