The paper focuses on linear stability analysis of natural convection in partially porous tall annular cavities. In order to analyze the dependence of this phenomenon on the cavity geometry, different values of radii ratio (ro/ri) have been considered; moreover, the influence of porous layer is investigated by considering several values of Da numbers and by changing the position of the internal porous domain. A transient Artificial Compressibility version of CBS algorithm is introduced here for the solution of the generalized Navier-Stokes equations; a dual time stepping approach is introduced in the scheme in order to employ a local time stepping procedure, suitable for applications in problem involving free fluid- porous medium interfaces. The numerical results highlight that linear stability of free convection in partially porous tall annuli is strongly affected both by the geometry and porous layer, as transient oscillations tend to disappear as radii ratio increases and Da number decreases; moreover, also the position of the porous layer seems to affect the stability analysis, as this trend is more noticeable when the porous domain is near the cold wall.
LINEAR STABILITY ANALYSIS OF NATURAL CONVECTION IN PARTIALLY POROUS TALL ANNULI
N. Massarotti;G. Cortellessa
2016-01-01
Abstract
The paper focuses on linear stability analysis of natural convection in partially porous tall annular cavities. In order to analyze the dependence of this phenomenon on the cavity geometry, different values of radii ratio (ro/ri) have been considered; moreover, the influence of porous layer is investigated by considering several values of Da numbers and by changing the position of the internal porous domain. A transient Artificial Compressibility version of CBS algorithm is introduced here for the solution of the generalized Navier-Stokes equations; a dual time stepping approach is introduced in the scheme in order to employ a local time stepping procedure, suitable for applications in problem involving free fluid- porous medium interfaces. The numerical results highlight that linear stability of free convection in partially porous tall annuli is strongly affected both by the geometry and porous layer, as transient oscillations tend to disappear as radii ratio increases and Da number decreases; moreover, also the position of the porous layer seems to affect the stability analysis, as this trend is more noticeable when the porous domain is near the cold wall.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
