TY - JOUR
T1 - Enhancement of natural convection of a nanofluid by stress-free patches in an L-shaped enclosure
AU - Ma, Yuan
AU - Tang, Hui
AU - Wang, Chenglei
N1 - Funding Information:
Chenglei Wang gratefully acknowledges financial support from the Start-up and Postdoc Matching Funds of The Hong Kong Polytechnic University (Project No. P0035137 and P0036711).
Publisher Copyright:
© 2023, Emerald Publishing Limited.
PY - 2023
Y1 - 2023
N2 - Purpose: This study aims at investigating the heat transfer characteristics of a nonsquare enclosure when hydrodynamic resistance is altered discontinuously along its inner surface. Particularly, it focuses on investigating how several essential factors collaboratively influence the natural convection, including the Rayleigh number (Ra), the aspect ratio (AR), the nanoparticle volume fraction (ϕ) and the locations of changing hydrodynamic resistance. Design/methodology/approach: To achieve these objectives, an L-shaped enclosure of various AR is adopted, while zero local shear resistance is applied and modeled by stress-free (SF) patches of four distinct arrangements (corresponding to Cases 1–4). The nanofluid is modeled by Buongiorno’s two-phase model. The effects are explored using an in-house numerical framework based on a hybrid lattice Boltzmann-finite difference method with the total variation minimization scheme. Findings: The results show that when Ra is sufficiently large, i.e. Ra = 105, SF patches can generally enhance the heat transfer performance regardless of other factors. However, the ways of achieving those enhancements are different, which mainly depend on the arrangement of the SF patches and AR but are nearly independent of ϕ. The maximum improvement of heat transfer can be achieved in Case 3 with AR = 0.6, Ra = 105 and ϕ = 0.04, where the averaged Nusselt number is enhanced by 8.89%. Originality/value: This study presents a new scenario where the SF patches of various arrangements are applied to enhance the nanofluid natural convection of a nonsquared enclosure, and it reveals how the improvement is achieved and cooperatively affected by several important factors.
AB - Purpose: This study aims at investigating the heat transfer characteristics of a nonsquare enclosure when hydrodynamic resistance is altered discontinuously along its inner surface. Particularly, it focuses on investigating how several essential factors collaboratively influence the natural convection, including the Rayleigh number (Ra), the aspect ratio (AR), the nanoparticle volume fraction (ϕ) and the locations of changing hydrodynamic resistance. Design/methodology/approach: To achieve these objectives, an L-shaped enclosure of various AR is adopted, while zero local shear resistance is applied and modeled by stress-free (SF) patches of four distinct arrangements (corresponding to Cases 1–4). The nanofluid is modeled by Buongiorno’s two-phase model. The effects are explored using an in-house numerical framework based on a hybrid lattice Boltzmann-finite difference method with the total variation minimization scheme. Findings: The results show that when Ra is sufficiently large, i.e. Ra = 105, SF patches can generally enhance the heat transfer performance regardless of other factors. However, the ways of achieving those enhancements are different, which mainly depend on the arrangement of the SF patches and AR but are nearly independent of ϕ. The maximum improvement of heat transfer can be achieved in Case 3 with AR = 0.6, Ra = 105 and ϕ = 0.04, where the averaged Nusselt number is enhanced by 8.89%. Originality/value: This study presents a new scenario where the SF patches of various arrangements are applied to enhance the nanofluid natural convection of a nonsquared enclosure, and it reveals how the improvement is achieved and cooperatively affected by several important factors.
KW - Buongiorno’s two-phase model
KW - Hydrodynamic resistance
KW - L-shaped enclosure
KW - Nanofluid
KW - Natural convection
KW - Stress-free patches
UR - http://www.scopus.com/inward/record.url?scp=85147359840&partnerID=8YFLogxK
U2 - 10.1108/HFF-08-2022-0469
DO - 10.1108/HFF-08-2022-0469
M3 - Journal article
AN - SCOPUS:85147359840
SN - 0961-5539
JO - International Journal of Numerical Methods for Heat and Fluid Flow
JF - International Journal of Numerical Methods for Heat and Fluid Flow
ER -