Flow model for velocity distribution in fixed porous beds under isothermal conditions

Abstract

Abstract. In a brief survey of the previous work the limitations of the modified Darcy equation and of the vectorial form of the Ergun equation are discussed. To include the effect of wall friction on the flows the viscous resistance term is added to the vectorial form of the Ergun equation. Using the generalized Ergun equation a one-dimensional formulation is presented for flow of fluids through packed beds taking into account the variation of porosity along the radial direction. It is found that there is a reasonable agreement between the numerical and the experimental results and it is observed that the variation of porosity with radial position has greater influence on channeling of velocity near the walls. For the assumption of constant porosity the velocity profiles exhibit similar nature as the plug flow profiles with a thin boundary layer near the wall.

Similarity solutions for buoyancy induced flows in a saturated porous medium adjacent to impermeable horizontal surfaces

“…However the works of Roble et al [8], Benenati and Brosilow [9], Schwartz and Smith [10] and Chandrasekhara and Vortmeyer [11] clearly show that porosity and in turn the permeability has a minimum value away from the wall and has a maximum value at the wall. This variation is due to packing of particles of the porous medium.…”

Composite heat transfer in case of steady laminar flow of a gray fluid with large optical density past a horizontal plate embedded in a saturated porous medium

“…It is found from the Table 1 that the thickness A of the second boundary layer is always greater than the thickness of the first boundary layer 6 since ~ is greater than unity for all values of B. The values of B, the dimensionless porous parameter are kept low since the permeability at the wall increases due to the packing of the particles (see Chandrasekhara and Votmeyer [6], Benenati and Brosilow [7] Chandrasekhara et al [8], Chandrasekhara [9] and Chandrasekhara and Namboodiri [10]. However, it is observed from the results that the value of 4 does not …”

Impuls‐ und Stoffaustausch in gasdurchströmten Schüttungen von Hochtemperatur‐Reaktoren und Schachtöfen

“…[30,31,37] Dies ist die bekannte Potentialgleichung (Laplacesche Differentialgleichung). Geht man aber auf eine komplette Beschreibung aller Vorgange in der Schuttung unter Einbeziehung der wandnawand, so daD eine Vernachlassigung in diesem Zusammenhang als zulassig erscheint.…”

“…An der Wand selbst tritt eine mit Messungen von Schwartz et al [33] in Ubereinstimmung befindliche Geschwindigkeitsuberhohung auf. In modifizierter Form 1aDt sichder Verlaufder in [32] gemessenen Porositat am S,chuttungsrand nach [31] wiedergeben mit…”