A numerical investigation of conjugate thermal boundary layers in a differentially heated partitioned cavity filled with different fluids

Abstract

In this study, the instability mechanisms in the conjugate thermal boundary layers (TBLs) adjacent to a partition in a differentially heated dual-chamber cavity are investigated numerically. The two chambers of the cavity are filled with air (Pr = 0.71) and water (Pr = 8.58), and the partition is assumed to have a zero thickness. The effects of the aspect ratios of both chambers (Aair and Awater) and the overall temperature difference (ΔT) on the interactions between the conjugate air- and water-side TBLs are extensively investigated. It is found that Aair has a more significant impact on the instabilities of the TBLs than Awater. For a relatively small Aair (e.g., 10/3) and a relatively large Aair (e.g., 10), the water-side TBL resonates with the air-side TBL at the frequencies of the corner flow instabilities in the air chamber. For medium Aair (e.g., 4, 5, and 20/3), the air-side TBL becomes weakly turbulent, causing the water-side TBL to become chaotic. Furthermore, if ΔT is reduced, the air-side TBL becomes quasi-periodic, limiting the turbulence growth on the water side. A stability map illustrating the major instability mechanisms controlling the interactions between the conjugate TBLs is presented on the (Aair, Ra) domain for Awater = 5.