Numerical solution of thermal entry length problem with variable viscosities and viscous dissipation
01 Jun 1978-Vol. 11, Iss: 2, pp 73-79
TL;DR: A numerical solution of the thermal entry length problem for circular pipes with constant temperature boundaries and with a prescribed dependence of viscosity on temperature and viscous dissipation of some specified order is presented in this paper.
Abstract: A numerical solution of the thermal entry length problem for circular pipes with constant temperature boundaries and with a prescribed dependence of viscosity on temperature and viscous dissipation of some specified order are presented. The results indicate a significant effect of these factors. The results for both heating and cooling processes are presented and compared with the available analytical results. They are useful in the design of heat exchangers with high Prandtl number fluids as the working media.
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TL;DR: In this paper, the authors evaluate the impact of simplifying assumptions in the treatment of the transport equations and the thermal conditions, as well as evaluate the feasibility of adapting simpler models, and find that the necking shape, heat transfer coefficient and furnace temperature profiles have a decisive impact on the overall solution.
62 citations
01 Jun 1983
TL;DR: In this article, the influence of viscous dissipation on the thermal entrance region laminar pipe flow heat transfer with convective boundary condition was considered and the Eigenfunction series expansion technique was employed to solve the governing energy equation.
Abstract: Consideration is given to the influence of viscous dissipation on the thermal entrance region laminar pipe flow heat transfer with convective boundary condition. The Eigenfunction series expansion technique is employed to solve the governing energy equation. The results for axial distributions of dimensionless bulk and wall temperatures, local Nusselt number as well as modified local Nusselt number are presented graphically forNu
0
=0.1, 2, and 100. The complicated variations of conventional local Nusselt number is due to the inappropriate definition of conventional heat transfer coefficient in this problem. A modified local heat transfer coefficient, based on the difference of bulk fluid temperature and wall temperature, is introduced. Its value can clearly indicate the extent and the direction of heat exchange between the fluid in the pipe and the ambient. The effects of outside Nusselt number are also investigated. Significant viscous dissipation effects have been observed for large Br.
56 citations
TL;DR: In this article, a finite-difference method for various Brinkman numbers (Br) and Peclet numbers (Pe) is presented graphically for non-Newtonian fluids described by the power-law model with the flow index of n = 0.5, 1.0 and 1.5.
51 citations
TL;DR: In this paper, the axisymmetric free-surface flow and thermal transport of fused silica during optical fiber drawing was considered with variable properties, prescribed heat flux, and neck shape.
Abstract: The axisymmetric free-surface flow and thermal transport of fused silica during optical fiber drawing was considered with variable properties, prescribed heat flux, and neck shape. Experimental data from previous researchers were adapted or used as the basis for assumptions in order to enable a realistic analysis. The main objectives were to model the neck-down process in order to clarify the effects of the variable properties and the associated viscous dissipation. Due to the large changes in dimension and viscosity, this system poses severe nonlinearities, and a new solution algorithm was necessarily developed. Validation was achieved and several important results were obtained. Among these, it was shown that the viscous dissipation has considerable impact on the fiber temperature due to its localization to a small volume near the fiber section. Also, it was shown that a variable viscosity generated vorticity, which was localized to the region where the preform radius undergoes large changes.
27 citations
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4,135 citations
01 Jan 1967
TL;DR: In this article, differentielles and stabilite were used for differentiable transport in the context of transfert de chaleur and ondes Reference Record created on 2005-11-18, modified on 2016-08-08
Abstract: Keywords: equations : differentielles ; stabilite ; transport ; transfert de chaleur ; mecanique des : fluides ; ondes Reference Record created on 2005-11-18, modified on 2016-08-08
3,449 citations
Book•
22 May 1998
TL;DR: In this paper, the analogy between heat and mass transfer is covered and applied in the analysis of heat transfer by conduction, convection and radiation, and the analysis is performed by using the handbook of numerical heat transfer.
Abstract: Handbook of Numerical Heat Transfer Free Full Download Links from Multiple Mirrors added by DL4W on 2015-04-10 02:13:35. Handbook of heat transfer / editors, W.M. Rohsenow, J.P. Hartnett. Y.I. Cho. m 3rd ed. p. cm. Includes bibliographical references and index. ISBN 0-07053555-8. Students investigate heat transfer by conduction, convection and radiation. The analogy between heat and mass transfer is covered and applied in the analysis.
564 citations
338 citations