Forced Convective Heat Transfer in a Plate Channel Filled with Solid Particles

A numerical study of fluid flow and convective heat transfer in a plate channel filled with solid (metallic)particles is presented in this paper.The study uses the thermal equilibrium model and a newly developed numerical model which does not assume idealized local thermal equilibrium between the solid particles and the fluid.The numerical simulation results are compared with the experimental data in reference[2].The paper investigates the effects of the assumption of local thermal equilibrium versus non-thermal equilibrium,the thermal conductivity of the solid particles and the particle diameter on convective heat transfer.For the conditions studied,the convective heat transfer and the temperature field assuming local thermal equilibrium are much different from that for the non-thermal equilibrium assumption when the difference between the solid and fluid thermal conductivities is large. The relative values of the thermal conductivities of the solid particles and the fluid also have a profound effect on the temperature distribution in the channel.The pressure drop decreases as the particle diameter increases and the convective heat transfer coefficient may decrease or increase as the particle diameter increases depending on the values of ε,λs,λf,λd,αv, ρu.

The Asymptotic Behavior and the Quasineutral Limit for the Bipolar Euler-Poisson System with Boundary Efects and a Vacuum

In this paper, a one-dimensional bipolar Euler-Poisson system （a hydrodynamic model） from semiconductors or plasmas with boundary effects is considered. This system takes the form of Euler-Poisson with an electric field and frictional damping added to the momentum equations. The large-time behavior of uniformly bounded weak solutions to the initial-boundary value problem for the one-dimensional bipolar Euler-Poisson system is firstly presented. Next, two particle densities and the corresponding current momenta are verified to satisfy the porous medium equation and the classical Darcy＇s law time asymp- totically. Finally, as a by-product, the quasineutral limit of the weak solutions to the initial-boundary value problem is investigated in the sense that the bounded L∞ entropy solution to the one-dimensional bipolar Euler-Poisson system converges to that of the cor- responding one-dimensional compressible Euler equations with damping exponentially fast as t → ＋∞. As far as we know, this is the first result about the asymptotic behavior and the quasineutral limit for the one-dimensional bipolar Euler-Poisson system with boundary effects and a vacuum.