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  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 20 (1995), S. 459-468 
    ISSN: 0271-2091
    Keywords: heat transfer ; turbulent flow ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The accurate modelling of heat transfer to turbulent flow and the prediction of the temperature distribution in the flow remain one of the problem areas of numerical simulations. Traditional turbulence closure models, like the k-ε model, effectively only increase the viscosity of the fluid and introduce wall functions close to boundaries to obtain the correct velocity distribution. These turbulence models do not model the small-scale mixing that occurs in turbulent flow. When solving the energy equation these small-scale mixings dominate the heat transfer rate at the boundaries as well as the temperature distribution in the flow. This paper outlines a revised method, based on the k-ε turbulence model, that can be used to predict heat transfer in turbulent flow. A single turbulent conductivity term is introduced that can be used over the complete flow field including the boundaries. A detailed description of the mathematical model and boundary conditions used for the turbulence model are included in the paper. The effective turbulent conductivity method was evaluated in several finite difference simulations of water flowing through a smooth pipe while being heated. Simulation and verification were performed over a range of Reynolds numbers. Verification of the model is accomplished by comparing the numerically predicted centre temperature of the fluid as well as the heat flux to the fluid to measured temperatures in a similar pipe. From these results it is concluded that the revised turbulent conductivity model holds great potential to obtain accurate simulated heat transfer rates for general applications.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996), S. 223-228 
    ISSN: 1069-8299
    Keywords: Discretization ; heat conduction ; simulation ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A different approach to discretization is described with which complicated three-dimensional heat transfer problems can be solved with a finite volume approach on a general curvilinear grid. It represents an improvement on the existing methods in that it can easily be expanded to three-dimensional problems. A concise explanation of the transformation process is given, together with a discussion of the discretization procedure. The method is evaluated by solving two simple test problems and comparing the results with those of existing methods and the analytical solution. In conclusion it is found that this method yields equally or more accurate results than the existing methods, with the additional advantage of being easily expandable to three-dimensional problems.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 10 (1994), S. 33-42 
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Reduction of reheating time saves on energy input and increases the production rate in the steel-making process. Reductions can be achieved by allowing the centre temperature of a steel bar to be lower than the surface temperature by a small margin, before starting with the hot rolling process. This can only be done if the temperature difference does not adversely affect the quality of the final product or the rolling equipment. The paper presents numerical simulations to investigate the savings that can be obtained for various temperature differences between surface and centre temperatures to evaluate the feasibility of the concept. The results presented include the cross-sectional temperature distribution in a typical steel bar during reheating at hourly intervals as well as the effect of various differences between centre and surface temperatures on reheating time. The reheating time predicted for various steel bar sizes as well as for various differences between surface and centre temperatures are then compared against measured reheating times. To indicate the practical applicability of the concept to the hot rolling process the detailed temperature distribution in a typical steel bar, with an initial temperature difference between the surface and centre of the bar, was simulated numerically. This was compared to a similar simulation for a well soaked steel bar for which experimental measurements are also available. The numerical method used to obtain the simulations is also presented. Boundary conditions account for radiation, convection and conduction inside the steel bar. It is concluded that the concept of allowing differences between surface and centre temperatures of a steel bar during reheating holds great potential for energy savings in the steel-making process.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Communications in Applied Numerical Methods 4 (1988), S. 657-664 
    ISSN: 0748-8025
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: By modelling the heat transfer in and around a hot-rolled steel bar, the temperature distribution in the bar can be predicted at any stage of the hot rolling process. Knowledge of these temperatures is useful when the process is to be optimized. This paper presents a finite difference simulation of the heat transfer and resulting temperature distribution. The numerical procedure accounts for thermal radiation from the bar, convective heat transfer to the atmosphere and cooling water, and conduction between the moving bar and the mill rolls and manipulators. Measured values for convective heat transfer coefficients are used at the boundaries. The following effects are also accounted for in the procedure: deformation of the bar during rolling, tilting the bar between passes through a mill, cropping the bar and contraction resulting from heat losses. Predicted and measured temperatures correlate favourably.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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