Natural Convection Heat Transfer in Enclosures

Natural convection in enclosed cavities arises when temperature differences between heated and cooled boundaries generate density gradients that drive buoyancy-induced fluid motion. Within simple geometries such as rectangular, circular or polygonal enclosures, the interplay of buoyancy, viscous dissipation and thermal diffusion gives rise to distinctive flow patterns ranging from single-cell laminar circulation to multi-vortex regimes as the Rayleigh number increases. The shape and arrangement of inner obstacles, wall inclinations and the properties of working fluids critically influence the strength and stability of convective currents. This mechanism underpins passive cooling of electronic components, solar updraft devices, energy storage modules and temperature regulation in spacecraft. Advanced studies now explore the effects of non-Newtonian rheology, nanoparticle suspensions and magnetic fields, while numerical and experimental approaches continue to refine predictive correlations for heat transfer coefficients and flow bifurcation thresholds across a broad range of Rayleigh and Prandtl numbers.

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Natural Convection Heat Transfer in Enclosures publication trend

The graph below shows the total number of articles in natural convection heat transfer in enclosures across all publications each year (not limited to Nature Index journals).

Technical terms

Rayleigh number: Dimensionless quantity expressing the ratio of buoyancy to viscous and thermal diffusion forces, determining the onset and intensity of natural convection.

Prandtl number: Ratio of momentum diffusivity (viscosity) to thermal diffusivity, indicating the relative thickness of velocity and thermal boundary layers in a fluid.

Nusselt number: Dimensionless measure of convective heat transfer enhancement, defined as the ratio of convective to conductive heat flux across a boundary.

Laminar flow: Flow regime characterised by smooth, orderly fluid motion with layers sliding past one another and minimal cross-stream mixing.

References

1. Heat Transfer Enhancement of MHD Natural Convection in a Star-Shaped Enclosure, Using Heated Baffle and MWCNT–Water Nanofluid. Mathematics (2023).
2. Numerical Investigation into the Natural Convection of Cryogenic Supercritical Helium in a Spherical Enclosure. Energies (2021).
3. Classification of Flow Modes for Natural Convection in a Square Enclosure with an Eccentric Circular Cylinder. Energies (2021).