Patterned convection in inclined slots

Floryan, J. M.; Baayoun, Abdelkader; Panday, S.; Bassom, Andrew P.

doi:10.1017/jfm.2022.793

Cited by 3 publications

(2 citation statements)

References 27 publications

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“…We remark that the intriguing concept of a horizontal chimney effect that relies on pattern interaction has been recently proposed (Floryan et al. 2022 a ).…”

Section: Introductionmentioning

confidence: 72%

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The reduction of pressure losses in thermally modulated vertical channels

2023

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The role played by patterned heating in reducing pressure losses within vertical conduits is investigated. The heating generates flow separation structures which reduce the direct contact between the stream and the sidewalls, thereby limiting the frictional resistance. This also modifies the temperature field thereby inducing a net buoyancy force which may either assist or oppose the pressure gradient required to maintain a fixed flow rate. If the flow Reynolds number is increased sufficiently, the separation structures may be washed away, which means that the pressure-gradient-reducing mechanism is eliminated. The details of the system response are a function of the form of spatial heating distribution, its intensity, the flow Reynolds number and the fluid Prandtl number. Carefully chosen heating of the two walls can induce a pattern interaction effect and a judicious choice of the two patterns can have as much as an order of magnitude effect on the system response.

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“…We remark that the intriguing concept of a horizontal chimney effect that relies on pattern interaction has been recently proposed (Floryan et al. 2022 a ).…”

Section: Introductionmentioning

confidence: 72%

“…The strength of the chimney effect can be significantly enhanced by using it in conjugation with an externally imposed pressure gradient. We remark that the intriguing concept of a horizontal chimney effect that relies on pattern interaction has been recently proposed (Floryan et al 2022a).…”

Section: Introductionmentioning

confidence: 85%

The reduction of pressure losses in thermally modulated vertical channels

2023

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The use of patterned heating in controlling pressure losses within sloping channels

Floryan,

Wang,

Bassom

2024

J. Fluid Mech.

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The effectiveness of utilizing heating patterns as a drag-reduction tool in sloping channels is analysed. The usefulness of heating is judged by determining the pressure gradient required to maintain the same flow rate as in the isothermal case. The key to reducing pressure loss is the formation of separation bubbles, although these bubbles are washed away at relatively large Reynolds numbers. The bubbles reduce the direct contact between the stream and the side walls, thereby reducing the friction experienced by the flow. Moreover, the fluid inside the bubbles tends to rotate, a motion provoked by longitudinal temperature gradients. This rotation also seems to reduce the resistance. On the other hand, the existence of the bubbles tends to obstruct the stream, increasing the flow resistance. In general, channels oriented close to horizontal experience a relatively small pressure loss, but this loss grows markedly as the channel inclines towards the vertical. When modest heating is applied, the pressure loss is approximately proportional to the square of the associated Rayleigh number. It is also shown that if the heating wavelength is too short or too long, the heating loses its effectiveness. In certain circumstances, it turns out that the theoretical pressure-gradient reduction achieved by judicious heating is so large that it exceeds the pressure gradient required to drive the flow in the isothermal problem. The conclusion is that in these instances, a pressure gradient of the opposite sign must be applied to prevent flow acceleration.

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Thermal drift in an inclined viscous fluid flow

Jovanovic,

Milanovic,

Boricic

et al. 2023

THERM SCI

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This paper considers viscous fluid flow in a slot between two parallel plates which start inclining with respect to the horizontal line. The lower plate was heated and had nonhomogeneous temperature distribution while the upper plate was cooled and with homogeneous temperature distribution. The spatially periodic temperature distribution was gradually applied at the lower plate, after which the plates were slowly inclined in the positive-counterclockwise direction, and the fields of vorticity, streamfunction and temperature are pesented for different values of the angle of inclination. We used the vorticity-streamfunction formulation of Navier-Stokes equations, Fourier-Galerkin and Chebyshev collocation method for numerical simulation of 2D viscous fluid flow. We carried out numerical simulation using our in-house Matlab code for subcritical uniform Rayleigh number Rauni, and periodic Rayleigh number Rap on the lower plate. An accurate numerical scheme was developed to capture the full time-dependent behavior here. The interest lied in how the intensities of the vortexes and convection rolls changed as the inclination angle was increased with respect to time. Convection rolls rotating in the clockwise direction expanded and the rolls rotating in the counterclockwise direction shrank and their centers moved closer to the lower wall. Thermal drift appeared between them when the inclination angle started increasing.

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Patterned convection in inclined slots

Cited by 3 publications

References 27 publications

The reduction of pressure losses in thermally modulated vertical channels

The reduction of pressure losses in thermally modulated vertical channels

The use of patterned heating in controlling pressure losses within sloping channels

Thermal drift in an inclined viscous fluid flow

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