TY - JOUR
T1 - An entropy generation analysis of horizontal convection under the centrifugal buoyancy approximation
AU - Mayeli, Peyman
AU - Sheard, Gregory J.
N1 - Funding Information:
This research was supported by the Australian Research Council through Discovery Project DP180102647 . P. M. is supported by a Monash Graduate Scholarship and a Monash International Postgraduate Research Scholarship . The authors are also supported by time allocations on the National Computational Infrastructure (NCI) peak facility and the Pawsey Supercomputing Centre through NCMAS grants. NCI is supported by the Australian Government .
Publisher Copyright:
© 2022 Elsevier Ltd
PY - 2022/4
Y1 - 2022/4
N2 - An entropy generation analysis is conducted for horizontal convection under the centrifugal buoyancy and the Boussinesq approximations in a relatively shallow enclosure at a fixed Prandtl number of unity to characterise irreversible losses across the conduction and convection-dominated regimes using the Bejan number (Be). A variable irreversibility distribution factor is expressed for the entropy generation analysis as a ratio of the Brinkman number (Br) and the Gay-Lussac (Ga) parameter for the first time. Governing equations are solved numerically using a high-order nodal spectral-element method. Calculations are performed at a fixed Br = 2 × 10−5 over the physical range of the Gay-Lussac parameter 0 ≤ Ga ≤ 2 up to Ra = 5 × 108. As expected, increasing the Rayleigh number shifts the flow toward a convection-dominated regime; however it is found that increasing the Gay-Lussac parameter draws the heat transfer mechanism back to a conduction-dominated state. In other words, advection related buoyancy effects act to keep the buoyancy-driven flow in conduction-dominated regime. The entropy generation analysis indicates that at Ga ≳ 0.5 conduction and convection are in balance at Ra ≈ 6 × 105, while under the conventional Boussinesq approximation (Ga = 0), heat transfer is convection-dominated. The transition of the average Bejan number from conduction to convection-dominated regime follows closely to a reciprocal scaling against Rayleigh number Beave~Ra−1 when Ga = 0 but the same process scales with Beave~Ra−0.5 relation at Ga = 2.
AB - An entropy generation analysis is conducted for horizontal convection under the centrifugal buoyancy and the Boussinesq approximations in a relatively shallow enclosure at a fixed Prandtl number of unity to characterise irreversible losses across the conduction and convection-dominated regimes using the Bejan number (Be). A variable irreversibility distribution factor is expressed for the entropy generation analysis as a ratio of the Brinkman number (Br) and the Gay-Lussac (Ga) parameter for the first time. Governing equations are solved numerically using a high-order nodal spectral-element method. Calculations are performed at a fixed Br = 2 × 10−5 over the physical range of the Gay-Lussac parameter 0 ≤ Ga ≤ 2 up to Ra = 5 × 108. As expected, increasing the Rayleigh number shifts the flow toward a convection-dominated regime; however it is found that increasing the Gay-Lussac parameter draws the heat transfer mechanism back to a conduction-dominated state. In other words, advection related buoyancy effects act to keep the buoyancy-driven flow in conduction-dominated regime. The entropy generation analysis indicates that at Ga ≳ 0.5 conduction and convection are in balance at Ra ≈ 6 × 105, while under the conventional Boussinesq approximation (Ga = 0), heat transfer is convection-dominated. The transition of the average Bejan number from conduction to convection-dominated regime follows closely to a reciprocal scaling against Rayleigh number Beave~Ra−1 when Ga = 0 but the same process scales with Beave~Ra−0.5 relation at Ga = 2.
KW - Centrifugal buoyancy approximation
KW - Entropy generation analysis
KW - Gay-Lussac parameter
KW - Horizontal convection
UR - http://www.scopus.com/inward/record.url?scp=85124612366&partnerID=8YFLogxK
U2 - 10.1016/j.icheatmasstransfer.2022.105923
DO - 10.1016/j.icheatmasstransfer.2022.105923
M3 - Article
AN - SCOPUS:85124612366
SN - 0735-1933
VL - 133
JO - International Communications in Heat and Mass Transfer
JF - International Communications in Heat and Mass Transfer
M1 - 105923
ER -