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Title: On the heat flux vector for flowing granular materials--part II: derivation and special cases

Heat transfer plays a major role in the processing of many particulate materials. The heat flux vector is commonly modelled by the Fourier's law of heat conduction and for complex materials such as non-linear fluids, porous media, or granular materials, the coefficient of thermal conductivity is generalized by assuming that it would depend on a host of material and kinematical parameters such as temperature, shear rate, porosity or concentration, etc. In Part I, we will give a brief review of the basic equations of thermodynamics and heat transfer to indicate the importance of the modelling of the heat flux vector. We will also discuss the concept of effective thermal conductivity (ETC) in granular and porous media. In Part II, we propose and subsequently derive a properly frame-invariant constitutive relationship for the heat flux vector for a (single phase) flowing granular medium. Standard methods in continuum mechanics such as representation theorems and homogenization techniques are used. It is shown that the heat flux vector in addition to being proportional to the temperature gradient (the Fourier's law), could also depend on the gradient of density (or volume fraction), and D (the symmetric part of the velocity gradient) in an appropriate manner. Themore » emphasis in this paper is on the idea that for complex non-linear materials it is the heat flux vector which should be studied; obtaining or proposing generalized form of the thermal conductivity is not always appropriate or sufficient.« less
Authors:
Publication Date:
OSTI Identifier:
938571
Report Number(s):
DOE/NETL-IR-2006-164; NETL-TPR-1575
Journal ID: ISSN 0170-4214; TRN: US200820%%87
DOE Contract Number:
None cited
Resource Type:
Journal Article
Resource Relation:
Journal Name: Mathematical Methods in the Applied Sciences; Journal Volume: 29; Journal Issue: 13
Publisher:
John Wiley & Sons, Ltd.
Research Org:
National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV, and Albany, OR
Sponsoring Org:
USDOE - Office of Fossil Energy (FE)
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; GRANULAR MATERIALS; HEAT FLUX; HEAT TRANSFER; PARTICULATES; SOLIDS FLOW; FLOW MODELS; TEMPERATURE GRADIENTS; THERMAL CONDUCTIVITY granular materials; heat flux vector; constitutive relation; conduction; Fourier’s law