Formulation and implementation of coupled forced heat convection and heat conduction in DEM

This paper presents the development, implementation and verification of a coupled convective–conductive heat flow and transport model in the discrete element method (DEM). Thermal conduction is already available in DEM codes such as the particle flow code (PFC). However, current DEM codes rarely account for convective heat transport. There are many important phenomena in different applications that involve convective heat transport due to flow of fluid through permeable solid material, where the fluid and the permeable solids have different initial temperatures. Heat transfer from convection is dependent on the fluid flow velocity through existing and new instantaneously forming flow paths in solid and is typically much faster than conduction. The complete formulation of the heat convection model, its implementation and coupling with fluid flow and heat conduction in PFC2D, and its validation are described in detail. While DEM has been widely used for studying fundamental mechanisms in geomaterials, little effort has been devoted toward extending DEM for studying coupling between conductive heat flow and convective heat transport problems. The developments presented in this paper will enable application of DEM to study coupled hydro-thermo-mechanical processes in geomaterials such as in geothermal systems, hydrocarbon production, environmental engineering and nuclear waste storage.

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