Enhancing the flow and heat transfer in a convective cavity using symmetrical and adiabatic twin fins

Abstract

The enhancement of natural convection flow and the associated heat transfer in a differentially heated cavity with two horizontal adiabatic fins attached to each sidewall are numerically investigated at different Rayleigh numbers and with various fin positions in this study. The numerical approach is validated by both representative scales and experimental shadowgraph results. A typical double-plume flow regime is identified at both the early and fully-developed stages. The interaction of the two plumes is investigated in detail in this paper. With the increasing of the Rayleigh number, the separation frequency of the plume above both fins increases. It is also revealed that the separation frequency of the upstream plume at the quasi-steady stage does not only depend on the characteristics of the upstream flow, but also greatly depends on the position of the downstream fin. The frequency varies non-monotonically as the downstream fin moving toward the cavity ceiling, suggesting complex nonlinear characteristics. Compared to the scenario without any fin, the flow rate across the cavity is significantly boosted, which is increased by up to 136.2% at the early stage and 124.8% at the fully-developed stage. The heat transfer rate across the cavity having symmetrical fins on sidewalls is enhanced by up to 12.7% at a Rayleigh number of 3.68 × 109.