SPH as an Inverse Numerical Tool for the Prediction of Diffusive Properties in Porous Media

2007 ◽  
Vol 553 ◽  
pp. 171-189 ◽  
Author(s):  
Antonio C.M. Sousa ◽  
Fangming Jiang

Heat and mass transfer and fluid flow in porous media are usually characterized by, or associated with, the effective thermal conductivity, the effective mass diffusivity and the permeability, respectively. All these macroscopic quantities are conceptually established on a phenomenological “equivalence” basis. They may contain the influence of porous micro-structures upon the corresponding diffusive process; however, the detailed nature inside the porous medium is lumped and neglected. Pore scale numerical modelling has the potential of providing adequate meso-/micro- scale insight into the transport process in porous medium, as well as obtaining macroscopic properties, which can encompass the complex pore-structure details. Modelling heat/mass transfer and fluid flow in complicated porous micro-structures presents a major challenge to numerical methods due to their multiscale and multiphysics nature. A relatively-novel numerical technique - the meshless Lagrangian-based Smoothed Particle Hydrodynamics (SPH) method is thought to be capable of making a significant contribution to this research field. This work deals primarily with the SPH modelling of heat conduction and fluid flow in 2-D isotropic porous media. The porous matrix is formed by randomly including a different component into a base component. Various pore-structures are realized by changing the inclusion shape/size, or the relative arrangement condition between inclusions. Pore-scale heat transfer and fluid flow streams are visualized, and both heat transfer and fluid flow always follow, as expected, the paths of least resistance through the porous structures. In what concerns the effective thermal conductivity, for the porous media with the base component of larger bulk thermal conductivity, the “flexible” EMT model, which can accommodate, to some extent, the influence from the porous micro-structures on the effective thermal conductivity by adjusting the so-called flexible factor ff, gives effective thermal conductivities agreeable to the SPH predictions across the whole composition range if ff is taken to be ~ 4.5; the effective thermal conductivity shows a weak dependence on the inclusion shape/size and the relative arrangement condition between inclusions; however, for porous media with dispersed inclusions, which component has larger bulk thermal conductivity presents a strong effect upon the effective thermal conductivity. The SPH fluid flow simulation results confirm the macroscopic Darcy’s law to be valid only in the creeping flow regime; the dimensionless permeability (normalized by the squared characteristic dimension of the inclusions) is found to have an exponential dependence on the porosity within the intermediate porosity range, and the derived dimensionless permeability /""porosity relation is found to have only a minor dependence on either the relative arrangement condition between inclusions or the inclusion shape/area.

2013 ◽  
Vol 65 (3) ◽  
Author(s):  
Türküler Özgümüş ◽  
Moghtada Mobedi ◽  
Ünver Özkol ◽  
Akira Nakayama

Thermal dispersion is an important topic in the convective heat transfer in porous media. In order to determine the heat transfer in a packed bed, the effective thermal conductivity including both stagnant and dispersion thermal conductivities should be known. Several theoretical and experimental studies have been performed on the determination of the effective thermal conductivity. The aim of this study is to review the experimental studies done on the determination of the effective thermal conductivity of the packed beds. In this study, firstly brief information on the definition of the thermal dispersion is presented and then the reported experimental studies on the determination of the effective thermal conductivity are summarized and compared. The reported experimental methods are classified into three groups: (1) heat addition/removal at the lateral boundaries, (2) heat addition at the inlet/outlet boundary, (3) heat addition inside the bed. For each performed study, the experimental details, methods, obtained results, and suggested correlations for the determination of the effective thermal conductivity are presented. The similarities and differences between experimental methods and reported studies are shown by tables. Comparison of the correlations for the effective thermal conductivity is made by using figures and the results of the studies are discussed.


2015 ◽  
Vol 18 (4) ◽  
pp. 449-453 ◽  
Author(s):  
Abdulmajeed A. Mohamad ◽  
Jamel Orfi ◽  
H. Al-Ansary

2020 ◽  
Vol 9 (1) ◽  
pp. 338-351
Author(s):  
Usha Shankar ◽  
N. B. Naduvinamani ◽  
Hussain Basha

AbstractA two-dimensional mathematical model of magnetized unsteady incompressible Williamson fluid flow over a sensor surface with variable thermal conductivity and exterior squeezing with viscous dissipation effect is investigated, numerically. Present flow model is developed based on the considered flow geometry. Effect of Lorentz forces on flow behaviour is described in terms of magnetic field and which is accounted in momentum equation. Influence of variable thermal conductivity on heat transfer is considered in the energy equation. Present investigated problem gives the highly complicated nonlinear, unsteady governing flow equations and which are coupled in nature. Owing to the failure of analytical/direct techniques, the considered physical problem is solved by using Runge-Kutta scheme (RK-4) via similarity transformations approach. Graphs and tables are presented to describe the physical behaviour of various control parameters on flow phenomenon. Temperature boundary layer thickens for the amplifying value of Weissenberg parameter and permeable velocity parameter. Velocity profile decreased for the increasing squeezed flow index and permeable velocity parameter. Increasing magnetic number increases the velocity profile. Magnifying squeezed flow index magnifies the magnitude of Nusselt number. Also, RK-4 efficiently solves the highly complicated nonlinear complex equations that are arising in the fluid flow problems. The present results in this article are significantly matching with the published results in the literature.


Sign in / Sign up

Export Citation Format

Share Document