Numerical study of natural convection in an open cavity considering temperature-dependent fluid properties

In this work the numerical results of heat transfer calculations in an open cavity considering natural convection and temperature-dependent fluid properties are presented. The overall continuity, momentum, and energy equations in terms of primitive variables were solved numerically using the finite-volume method. Numerical calculations were conducted for Rayleigh number (Ra) values in the range of 104–107. The temperature difference between the hot wall and the bulk fluid (ΔT) was varied between 10 and 500 K, and was represented as a dimensionless temperature difference (ɛ) for the purpose of generalization of the trends observed. The results show that the thickness of the hydrodynamic boundary layer in the vicinity of the hot wall increases as ɛ increases from 0.03 to 1.6. The average Nusselt number in the cavity (Nu) was found to increase by 807% (ɛ = 0.03) and 1105% (ɛ = 1.6) as the Ra number varied from 104 to 107. Likewise, the average Nu number in the cavity decreased by 39% (Ra = 104) and 18% (Ra = 106) as ɛ was varied from 0.03 to 1.6.

► Temperature-dependent fluid properties were considered.
► Significant differences are observed with the Boussinesq approach.
► The thickness of the hydrodynamic boundary layer increases with ɛ.
► The average Nusselt number reduces with ɛ.