Effects of viscous dissipation and boundary conditions on forced convection in a channel occupied by a saturated porous medium

Forced convection with viscous dissipation in a parallel plate channel filled by a saturated porous medium is investigated numerically. Three different viscous dissipation models are examined. Two different sets of wall conditions are considered: isothermal and isoflux. Analytical expressions are also presented for the asymptotic temperature profile and the asymptotic Nusselt number. With isothermal walls, the Brinkman number significantly influences the developing Nusselt number but not the asymptotic one. At constant wall heat flux, both the developing and the asymptotic Nusselt numbers are affected by the value of the Brinkman number. The Nusselt number is sensitive to the porous medium shape factor under all conditions considered

Effects of viscous dissipation and boundary conditions on forced convection in a channel occupied by a saturated porous medium

Forced convection with viscous dissipation in a parallel plate channel filled by a saturated porous medium is investigated numerically. Three different viscous dissipation models are examined. Two different sets of wall conditions are considered: isothermal and isoflux. Analytical expressions are also presented for the asymptotic temperature profile and the asymptotic Nusselt number. With isothermal walls, the Brinkman number significantly influences the developing Nusselt number but not the asymptotic one. At constant wall heat flux, both the developing and the asymptotic Nusselt numbers are affected by the value of the Brinkman number. The Nusselt number is sensitive to the porous medium shape factor under all conditions considered

The effects of cimetidine on motor activity: an evaluation the role of opioid receptors

Introduction: Effects of cimetidine (CIM) on locomotor is controversial. This study was designed to evaluate the effects of CIM on motor activity and possible roles of opioid receptors in CIM-induced decrement in locomotor activity in mice. Materials & Methods: Thirty-six male mice (25-30gr) were divided into six groups in this study. Locomotor activity was evaluated using an automated activity monitor system. CIM (50 mgkg, i.p.) was injected 25 min before testing in presence or absence naloxone (2 mg/kg, sc). Morphine (5 mg/kg, i.p) was injected 25 min before testing in the presence or absence CIM. decreased motor activity significantly. Pretreatment of or morphine did not change CIM – induced response significantly. Results: The results showed that CIM significantly decreased motor activity in mice (P=0.000). Pretreatment of nalxone did not change CIM-induced response significantly. Morphine alone did not change motor activity. Pretreatment of CIM did not change morphine-induced response. Conclusion: Data indicated that cimetidine can reduce motor activity independence from interaction with opioid receptors

The influence of a fluid-porous interface on solar pond stability

The linear instability of the gradient zone of a solar pond containing a fluidporous interface is investigated. It is found that the gradient zone can retain the same stability for lower values of the solute Rayleigh number with the introduction of a porous material compared with a purely fluid layer, whilst maintaining the same lower convective zone temperature. Interestingly, it is also shown that for certain parameter values the penetration of a porous medium into the gradient zone can cause the temperature of the lower convective zone to rise. However, for certain parameter ranges, when the fluid-porous interface is towards the top of the gradient zone, the solar pond can become highly unstable.PostprintPeer reviewe

A theoretical analysis of forced convection in a porous-saturated circular tube: Brinkman-Forchheimer model

Fully developed forced convection inside a circular tube filled with saturated porous medium and with uniform heat flux at the wall is investigated on the basis of a Brinkman-Forchheimer model. The matched asymptotic expansion method is applied at small Darcy numbers. For large Darcy numbers, the solution for the Brinkman-Forchheimer momentum equation is found in terms of an asymptotic expansion. Once the velocity distribution is determined, the energy equation is solved using the same asymptotic technique. The results for the two limiting cases of clear fluid and Darcy flow conditions show good agreement with those available in the literature