Natural Convection from Two Cylinders in an Enclosure with Sinusoidal Bottom Wall: A Numerical Study

Unsteady laminar natural convection within a square enclosure with wavy bottom wall embedded with a couple of circular cylinders placed in the vertically symmetric mid-plane is numerically investigated. Present study numerically quests for four different interspacings of the cylinders ranges \(0.1 \le S \le 0.4\) and for Rayleigh number (Ra) in the range of 10³–10⁶. The results are discussed based on distribution of isotherms, streamlines, and temporal distribution of surface-averaged Nusselt number (Nu_s) along with the time-averaged Nusselt number (Nu_t). The outcome of the investigation infers that heat transfer takes place solely due to conduction up to Ra = 10³, whereas the heat transfer shifts the mode from conduction to convection with increase in Ra. Further, Nu_t is found to increase with increase in S at lower values of Ra. Moreover, for higher values of Ra, the variation of Nu_t evaluated at the surface of the cylinders shows contrasting features with changing cylinder spacing.