Natural Convection Heat Transfer in a Cubic Cavity Submitted to Time-Periodic Sidewall Temperature

Abstract

The laminar unsteady natural convection in a cubic cavity is comprehensively studied here using a high accuracy temporal-spatial pseudospectral method. In this study, the cavity is filled with air and one of its sidewalls is submitted to sinusoidally varying temperature, while constant lower temperature is imposed on the opposing sidewall and other sidewalls are adiabatic. Computations are performed to explore the effects of several influential factors on the fluid flow patterns and heat transfer performances within the cavity, including Rayleigh number and the amplitude and period of pulsating sidewall temperature. Numerical results reveal that the heat transfer enhancement is complexly determined by the above influential factors, and the heat transfer resonance is observed in the case of a large Rayleigh number and amplitude of pulsating sidewall temperature. The three-dimensional effects on fluid flow patterns and heat transfer are discussed. Finally, the backward heat transfer is quantitatively studied.

Heat transfer past rotationally oscillating circular cylinder heated with time‐periodic pulsating temperature in a uniform flow

“…Att t P = + (1) 0 , the negative temperature convects away downstream and the fluid surrounding the cylinder regains a F I G U R E 10 The variation of local Nusselt number (Nu) and isotherm contours over a period of temperature for Re = 180, α = 0.5 m , f f = 0.5 0 ∕ , a = 0.5 and (A) P = 0.01, (B) P = 0.1, (C) P = 1, (D) P = 10, (E) P = 100 F I G U R E 9 (A) Nu, ((B)-(F)) isotherm contours superimposed with streamlines during a period of temperature for Re = 180, Pr = 0.7, a = 1.5, P = 1, α = higher temperature. In this figure, Nu varies approximately in the range (−160, 170) for P = 0.01, (−100, 120) for P = 0.1, (−40, 50) for P = 1, (−14,34) for P = 10 and (−6, 30) for P = 100. The rate of heat transfer decreases as the period increases for this amplitude a = 1.5 of the pulsating temperature.…”

“…Their findings also suggested that increasing Rayleigh number decreased the backward heat transfer rate while the increasing temperature pulsating amplitude increased it. More detailed studies on time‐periodic pulsating temperature can be found in 29–35 …”

“…More detailed studies on timeperiodic pulsating temperature can be found in. [29][30][31][32][33][34][35] It can be seen that the heat transfer under natural convection for time-periodic pulsating temperature is studied over the years. Only a few works were done on heat transfer for pulsating temperature under forced convection but there is no reported result on heat transfer for time-periodic pulsating temperature from a circular cylinder under forced convection.…”

Thermal convection and radiation in a rotating cabinet with time-dependent heat-generated solid element and heat-conducting solid walls

“…Results have shown that the mean Nu and high temperature heavily depend on heating frequency and a rising of Ra reflects in energy transference enhancement. Huang et al (2014) have studied regimes of thermal convective transport in a cubic chamber having varying heated sidewall. The authors have claimed that the energy transmission augmentation is significantly dependent on Ra, sidewall pulsating period and amplitude.…”

Heat transfer enhancement of a natural convection flow in an enclosure submitted to a small extent thermal disturbance: Influence of location and frequency

“…In comparison to the mean heat transfer without disturbance, they found that the increase of the mean heat transfer with the disturbance is higher for shallow cavities. Finally, [30] considered a cubic cavity submitted to a sinusoidally-varying hot wall temperature. As for 2D studies, a resonance was observed for large Rayleigh numbers and was determined by the amplitude and the frequency of the disturbance.…”