Turbulence Modeling of Forced Convection Heat Transfer in Two-Dimensional Ribbed Channels

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
E. Elsaadawy ◽  
H. Mortazavi ◽  
M. S. Hamed
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Turbulence Model ◽  
Turbulence Modeling ◽  
Convection Heat Transfer ◽  
Turbulence Models ◽  
Experimental Results ◽  
Electronic Systems ◽  
Sst Turbulence Model ◽  
Stress Models

Although the problem of 2D ribbed channels has been studied heavily in the literature as a benchmark or basic case for cooling of electronic packing, there is still a contradiction in the literature about the suitable turbulence model that should be used in such a problem. The accuracy of the computational predictions of heat transfer rates depends mostly on the choice of the proper turbulence model that is capable of capturing the physics of the problem, and on the corresponding wall treatment. The main objective of this work is to identify the proper turbulence model to be used in thermal analysis of electronic systems. A number of available turbulence models, namely, the standard k-ε, the renormalization group k-ε, the shear stress transport (SST), the k-ω, and the Reynolds stress models, have been investigated. The selection of the most appropriate turbulence model has been based upon comparisons with both direct numerical simulations (DNSs) and experimental results of other works. Based on such comparisons, the SST turbulence model has been found to produce results in very good agreement with the DNS and experimental results and hence it is recommended as an appropriate turbulence model for thermal analysis of electronic packaging.

Numerical Study of Turbulent Flow Through Rib-Roughened Channels With Mist Injection

2014 ◽  
Author(s):  
Fifi N. M. Elwekeel ◽  
Qun Zheng ◽  
Antar M. M. Abdala
Keyword(s):  
Heat Transfer ◽  
Turbulence Model ◽  
Cross Sections ◽  
Numerical Study ◽  
Turbulence Models ◽  
Uniform Heat Flux ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Sst Turbulence Model ◽  
Volume Method

This study investigated heat transfer characteristics on various shaped ribs on the lower channel wall using steam and steam/mist as cooling fluid. The lower wall is subjected to a uniform heat flux condition while others walls are insulated. Calculations are carried out for ribs with square ribs (case A), triangular ribs (case B), trapezoidal ribs (case C) and (case D) cross sections over a range of Reynolds numbers (14000–35000), constant mist mass fraction (6%) and fixed rib height and pitch. To investigate turbulence model effects, computations based on a finite volume method, are carried out by utilizing three turbulence models: the standard k-ω, Omega Reynolds Stress (ωRS) and Shear Stress Transport (SST) turbulence models. The predicted results from using several turbulence models reveal that the SST turbulence model provide better agreement with available measurements than others. It is found that the heat transfer coefficients are enhanced in ribbed channels with injection of a small amount of mist. The steam/mist provides the higher heat transfer enhancement over steam when trapezoidal shaped ribs (38°, case C).

scholarly journals Numerical study of the low-Reynolds flows in the vertical heated caverns

2019 ◽  
Vol 213 ◽  
pp. 02065
Author(s):  
Mikhail Petrichenko ◽  
Vitaly Sergeev ◽  
Darya Nemova ◽  
Evgeny Kotov ◽  
Darya Tarasova
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Turbulence Model ◽  
Energy Equation ◽  
Numerical Study ◽  
Temperature Drop ◽  
Three Dimensional ◽  
Experimental Results ◽  
Sst Turbulence Model ◽  
Heated Plates

The object of research is the critical geometry of a three-dimensional air flow in a cavern between two vertical heated plates. In this rate the convection's contribution to heat transfer will be limited due to thermal conductivity at a fixture temperature drop. A three-dimensional RANS approach closed by the k-w SST turbulence model in conjunction with the energy equation. The model validated and verified by comparison with the experimental results. The results of the work applied in developing of ventilated façades.

Numerical calculation of turbulent convection heat transfer over infrared dome based on SST turbulence model

2016 ◽  
Vol 45 (7) ◽  
pp. 0703002
Author(s):  
罗海波 Luo Haibo ◽  
张代军 Zhang Daijun ◽  
惠斌 Hui Bin ◽  
常铮 Chang Zheng ◽  
徐保树 Xu Baoshu
Keyword(s):  
Heat Transfer ◽  
Numerical Calculation ◽  
Turbulence Model ◽  
Convection Heat Transfer ◽  
Turbulent Convection ◽  
Convection Heat ◽  
Sst Turbulence Model

An Investigation of Turbulence Modeling in Transonic Fans Including a Novel Implementation of an Implicit k–ε Turbulence Model

1993 ◽  
Vol 115 (2) ◽  
pp. 249-260 ◽  
Author(s):  
M. G. Turner ◽  
I. K. Jennions
Keyword(s):  
Turbulence Model ◽  
Turbulence Modeling ◽  
Turbulence Models ◽  
Algebraic Model ◽  
Experimental Results ◽  
Navier Stokes ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
Wall Functions ◽  
Solution Methods

An explicit Navier–Stokes solver has been written with the option of using one of two types of turbulence model. One is the Baldwin–Lomax algebraic model and the other is an implicit k–ε model which has been coupled with the explicit Navier–Stokes solver in a novel way. This type of coupling, which uses two different solution methods, is unique and combines the overall robustness of the implicit k–ε solver with the simplicity of the explicit solver. The resulting code has been applied to the solution of the flow in a transonic fan rotor, which has been experimentally investigated by Wennerstrom. Five separate solutions, each identical except for the turbulence modeling details, have been obtained and compared with the experimental results. The five different turbulence models run were: the standard Baldwin–Lomax model both with and without wall functions, the Baldwin–Lomax model with modified constants and wall functions, a standard k–ε model, and an extended k–ε model, which accounts for multiple time scales by adding an extra term to the dissipation equation. In general, as the model includes more of the physics, the computed shock position becomes closer to the experimental results.

Computational Analysis of Heat Transfer Enhancement Due to Rectangular Ribs in a Turbulent Duct Flow

2004 ◽  
Author(s):  
Alok Chaube ◽  
P. K. Sahoo ◽  
S. C. Solanki
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Turbulence Model ◽  
Computational Analysis ◽  
Turbulence Models ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Experimental Results ◽  
Duct Flow ◽  
Transfer Enhancement

A computational analysis of heat transfer enhancement due to artificial roughness in the form of rectangular ribs has been carried out. A turbulence model is selected by comparing the predictions of different turbulence models with experimental results available in the literature. A detailed analysis of heat transfer variation within inter rib region is done by using the selected turbulence model. The analysis shows that peak in local heat transfer coefficient occurs at the point of reattachment of the separated flow as observed experimentally. The results predict a significant enhancement of heat transfer in comparison to that for a smooth surface. There is a good matching between the predictions by SST k-ω and experimental results.

Numerical Study of Deteriorated Convection Heat Transfer of Supercritical Fluid Flowing Through Vertical Mini Tube at Relatively Low Reynolds Numbers

2018 ◽  
Author(s):  
Chen-Ru Zhao ◽  
Zhen Zhang ◽  
Qian-Feng Liu ◽  
Han-Liang Bo ◽  
Pei-Xue Jiang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Low Reynolds Number ◽  
Convection Heat Transfer ◽  
Turbulence Models ◽  
Convection Heat ◽  
Flow Acceleration ◽  
Heat Transfer Deterioration ◽  
Low Reynolds

Numerical investigations are performed on the convection heat transfer of supercritical pressure fluid flowing through vertical mini tube with inner diameter of 0.27 mm and inlet Reynolds number of 1900 under various heat fluxes conditions using low Reynolds number k-ε turbulence models due to LB (Lam and Bremhorst), LS (Launder and Sharma) and V2F (v2-f). The predictions are compared with the corresponding experimentally measured values. The prediction ability of various low Reynolds number k-ε turbulence models under deteriorated heat transfer conditions induced by combinations of buoyancy and flow acceleration effects are evaluated. Results show that all the three models give fairly good predictions of local wall temperature variations in conditions with relatively high inlet Reynolds number. For cases with relatively low inlet Reynolds number, V2F model is able to capture the general trends of deteriorated heat transfer when the heat flux is relatively low. However, the LS and V2F models exaggerate the flow acceleration effect when the heat flux increases, while the LB model produces qualitative predictions, but further improvements are still needed for quantitative prediction. Based on the detailed flow and heat transfer information generated by simulation, a better understanding of the mechanism of heat transfer deterioration is obtained. Results show that the redistribution of flow field induced by the buoyancy and flow acceleration effects are main factors leading to the heat transfer deterioration.

Computational Fluid Dynamics Evaluation of Heat Transfer Correlations for Sodium Flows in a Heat Exchanger

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Seok-Ki Choi ◽  
Seong-O Kim ◽  
Hoon-Ki Choi
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Turbulence Model ◽  
Numerical Solutions ◽  
Numerical Study ◽  
Cross Flow ◽  
Turbulence Models ◽  
Parallel Flow ◽  
Sst Model ◽  
Heat Transfer Correlations

A numerical study for the evaluation of heat transfer correlations for sodium flows in a heat exchanger of a fast breeder nuclear reactor is performed. Three different types of flows such as parallel flow, cross flow, and two inclined flows are considered. Calculations are performed for these three typical flows in a heat exchanger changing turbulence models. The tested turbulence models are the shear stress transport (SST) model and the SSG-Reynolds stress turbulence model by Speziale, Sarkar, and Gaski (1991, “Modelling the Pressure-Strain Correlation of Turbulence: An Invariant Dynamical System Approach,” J. Fluid Mech., 227, pp. 245–272). The computational model for parallel flow is a flow past tubes inside a circular cylinder and those for the cross flow and inclined flows are flows past the perpendicular and inclined tube banks enclosed by a rectangular duct. The computational results show that the SST model produces the most reliable results that can distinguish the best heat transfer correlation from other correlations for the three different flows. It was also shown that the SSG-RSTM high-Reynolds number turbulence model does not deal with the low-Prandtl number effect properly when the Peclet number is small. According to the present calculations for a parallel flow, all the old correlations do not match with the present numerical solutions and a new correlation is proposed. The correlations by Dwyer (1966, “Recent Developments in Liquid-Metal Heat Transfer,” At. Energy Rev., 4, pp. 3–92) for a cross flow and its modified correlation that takes into account of flow inclination for inclined flows work best and are accurate enough to be used for the design of the heat exchanger.

The Simulation Study of Turbulence Models for Conjugate Heat Transfer Analysis of a High Pressure Air-Cooled Gas Turbine

2010 ◽  
Author(s):  
Zhenfeng Wang ◽  
Peigang Yan ◽  
Hongfei Tang ◽  
Hongyan Huang ◽  
Wanjin Han
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbine ◽  
Turbulence Model ◽  
Conjugate Heat Transfer ◽  
Turbulence Models ◽  
Turbulence Characteristic ◽  
The Heat Transfer Coefficient

The different turbulence models are adopted to simulate NASA-MarkII high pressure air-cooled gas turbine. The experimental work condition is Run 5411. The paper researches that the effect of different turbulence models for the flow and heat transfer characteristics of turbine. The turbulence models include: the laminar turbulence model, high Reynolds number k-ε turbulence model, low Reynolds number turbulence model (k-ω standard format, k-ω-SST and k-ω-SST-γ-θ) and B-L algebra turbulence model which is adopted by the compiled code. The results show that the different turbulence models can give good flow characteristics results of turbine, but the heat transfer characteristics results are different. Comparing to the experimental results, k-ω-SST-θ-γ turbulence model results are more accurate and can simulate accurately the flow and heat transfer characteristics of turbine with transition flow characteristics. But k-ω-SST-γ-θ turbulence model overestimates the turbulence kinetic energy of blade local region and makes the heat transfer coefficient higher. It causes that local region temperature is higher. The results of B-L algebra turbulence model show that the results of B-L model are accurate besides it has 4% temperature error in the transition region. As to the other turbulence models, the results show that all turbulence models can simulate the temperature distribution on the blade pressure surface except the laminar turbulence model underestimates the heat transfer coefficient of turbulence flow region. On the blade suction surface with transition flow characteristics, high Reynolds number k-ε turbulence model overestimates the heat transfer coefficient and causes the blade surface temperature is high about 90K than the experimental result. Low Reynolds number k-ω standard format and k-ω-SST turbulence models also overestimate the blade surface temperature value. So it can draw a conclusion that the unreasonable choice of turbulence models can cause biggish errors for conjugate heat transfer problem of turbine. The combination of k-ω-SST-γ-θ model and B-L algebra model can get more accurate turbine thermal environment results. In addition, in order to obtain the affect of different turbulence models for gas turbine conjugate heat transfer problem. The different turbulence models are adopted to simulate the different computation mesh domains (First case and Second case). As to each cooling passages, the first case gives the wall heat transfer coefficient of each cooling passages and the second case considers the conjugate heat transfer course between the cooling passages and blade. It can draw a conclusion that the application of heat transfer coefficient on the wall of each cooling passages avoids the accumulative error. So, for the turbine vane geometry models with complex cooling passages or holes, the choice of turbulence models and the analysis of different mesh domains are important. At last, different turbulence characteristic boundary conditions of turbine inner-cooling passages are given and K-ω-SST-γ-θ turbulence model is adopted in order to obtain the effect of turbulence characteristic boundary conditions for the conjugate heat transfer computation results. The results show that the turbulence characteristic boundary conditions of turbine inner-cooling passages have a great effect on the conjugate heat transfer results of high pressure gas turbine.

Sensitivity Studies of Shear Stress Transport Turbulence Model Parameters on the Prediction of Seven-Rod Bundle Benchmark Experiments

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Cale Bergmann ◽  
S. Ormiston ◽  
V. Chatoorgoon
Keyword(s):  
Shear Stress ◽  
Turbulence Model ◽  
Turbulence Modeling ◽  
Sensitivity Study ◽  
Model Parameters ◽  
Rod Bundle ◽  
Shear Stress Transport ◽  
Sst Turbulence Model ◽  
Sensitivity Studies ◽  
Two Parameters

This paper reports the findings of a sensitivity study of parameters in the shear stress transport (SST) turbulence model in a commercial computational fluid dynamics (CFD) code to predict an experiment from the Generation IV International Forum Supercritical-Water-Cooled Reactor (GIF SCWR) 2013–2014 seven-rod subchannel benchmark exercise. This study was motivated by the result of the benchmark exercise that all the CFD codes gave similar results to a subchannel code, which does not possess any sophisticated turbulence modeling. Initial findings were that the CFD codes generally underpredicted the wall temperatures on the B2 case in the region where the flow was supercritical. Therefore, it was decided to examine the effect of various turbulence model parameters to determine if a CFD code using the SST turbulence model could do a better job overall in predicting the wall temperatures of the benchmark experiments. A sensitivity study of seven parameters was done, and changes to two parameters were found to make an improvement.

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