Abstract
In this paper, Rayleigh-Benard Convection (RBC) is investigated in a two-dimensional vertical cavity with the horizontal temperature gradient for Rayleigh numbers (Ra) up to 20000. The velocity and temperature fields along with the Nusselt number (Nu) are examined and discussed for various cases of aspect ratios (AR); 1 ≤ AR ≤ 100, along with examining the critical aspect ratio (ARcr). It is found that in the case of horizontal temperature gradient, convection starts at critical Rayleigh number ≈ 370. It is also observed that the fluid motion is initially restricted to wall proximity, but gradually as Ra increases, convection covers the whole cavity, including the core zone. Our numerical simulations show that as the AR increases beyond 13, for Ra = 6500 instabilities are observed in the cavity. Soon afterwards, secondary cells are formed and tend to decrease in number as Ra increases until the flow becomes fully turbulent. This computational study demonstrates that laminar and transition regimes get contracted with an increasing AR. Profiles of the averaged Nu for different AR are also provided on log Ra-log Nu map. The key finding of this research relates to the dependence of Nu on AR and Ra.
