Fluid Dynamics and Heat Transfer in Curved Ducts

Flow through curved ducts departs markedly from straight‐channel behaviour due to centrifugal forces that drive cross‐stream secondary motions, commonly referred to as Dean vortices. These vortical structures enhance mixing, redistribute momentum and heat, and precipitate instabilities as the Reynolds number or curvature ratio increases. In thermal applications, the interplay of forced convection and buoyancy gives rise to complex temperature fields and bifurcation phenomena. Parameters such as the Dean number, which quantifies the ratio of centrifugal to viscous forces, and the Grashof number, characterising buoyancy effects, dictate transitions between steady, oscillatory and chaotic flow regimes. Geometry—aspect ratio, curvature ratio and cross-sectional shape—further modulates vortex size, location and heat‐transfer coefficient, often expressed via the Nusselt number. Understanding these interactions has direct implications for heat‐exchanger design, cooling channels in high-performance electronics, and fluidic components in chemical and biomedical engineering, where curved duct configurations are exploited to augment thermal performance and control flow stability.

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Fluid Dynamics and Heat Transfer in Curved Ducts publication trend

The graph below shows the total number of articles in fluid dynamics and heat transfer in curved ducts across all publications each year (not limited to Nature Index journals).

Technical terms

Dean number: Dimensionless group quantifying the ratio of centrifugal to viscous forces in curved duct flow.

Grashof number: Dimensionless parameter representing the ratio of buoyancy to viscous forces in natural convection.

Nusselt number: Dimensionless measure of convective heat transfer relative to conductive heat transfer.

Secondary flow: Transverse fluid motion, often vortical, induced by curvature or rotation in a duct.

Centrifugal instability: Flow instability arising from fluid acceleration along curved streamlines under centrifugal forces.

References

1. A computational modeling on transient heat and fluid flow through a curved duct of large aspect ratio with centrifugal instability. The European Physical Journal Plus (2021).
2. A computational modeling on two-dimensional laminar flow and thermal characteristics through a strongly bent square channel. AIP Advances (2023).
3. PIV-Measurements of Centrifugal Instabilities in a Rectangular Curved Duct with a Small Aspect Ratio. Fluids (2021).