Recent trends in natural-convection research are the finding of new configurations to improve heat transfer parameters or the analysis of standard configurations to determine optimal geometric parameters in order to achieve a better heat transfer rate. In this article a numerical simulation of natural convection in air in a channel–chimney system heated symmetrically at uniform heat flux is carried out. The regime analyzed is two-dimensional, laminar, and steady-state. Wall temperature profiles, air velocity and temperature profiles, and centerline pressure profiles are presented. A comparison with experimental data given in [ 4 A. Auletta , O. Manca , B. Morrone , and V. Naso , Heat Transfer Enhancement by the Chimney Effect in a Vertical Isoflux Channel , Int. J. Heat Mass Transfer , vol. 44 , pp. 4345 – 4357 , 2001 . [CROSSREF] [CSA] [Crossref], [Web of Science ®] [Google Scholar] ] is accomplished and some differences are observed, but thermal and dynamic behavior for different expansion ratios are the same. Results analysis explains how and why the “chimney effect” worsens. The effect is connected to the cold inflow at the outlet section, and this effect is more marked at higher Rayleigh number, Ra. Consequently, optimal thermal configuration for assigned extension ratio presents a larger value of expansion ratio at the lower Ra. values.

In this paper, the effect of coupled thermal dilation and stress on interstitial fluid transport in tumour tissues is evaluated. The tumour is modelled as a spherical deformable poroelastic medium embedded with interstitial fluid, while the transvascular fluid flow is modelled as a uniform distribution of fluid sink and source points. A hyperbolic-decay radial function is used to model the heat source generation along with a rapid decay of tumour blood flow. Governing equations for displacement, fluid flow and temperature are first scaled and then solved with a finite-element scheme. Results are compared with analytical solutions from the literature, while results are presented for different scaling parameters to analyse the various physical phenomena. Results show that temperature affects pressure and velocity fields through the deformable medium. Finally, simulations are performed by assuming that the heat source is periodic, in order to assess the extent to which this condition affects the velocity field. It is reported that in some cases, especially for periodic heating, the combination of thermoelastic and poroelastic deformation led to no monotonic pressure distribution, which can be interesting for applications such as macromolecule drug delivery, in which the advective contribution is very important owing to the low diffusivity.