Effect of concave and convex side-wall curvature on natural convective heat transfer in trapezoidal enclosures

Yıl 2026, Cilt: 11 Sayı: 1, 437 - 460, 17.03.2026

Çağatay Yıldız

https://doi.org/10.58559/ijes.1861704

https://izlik.org/JA23FU28MU

Öz

Focusing on the enhancement effects of fluid flow alteration on natural convective heat transfer in enclosures, this study presents a numerical investigation about natural convection behavior inside the concave and convex shaped trapezoidal-based enclosures. The side walls of a two-dimensional standard isosceles trapezoidal enclosure (TE) were modified to constitute concave and convex enclosures based on the reference geometry. Regarding the wall curvature, three different concave (C1, C2, and C3) and three different convex (V1, V2, and V3) enclosures were examined in terms of natural convective heat transfer, considering three different Rayleigh numbers (Ra=10⁴, 10⁵, and 10⁶). The governing equations of the problem was solved by finite volume based commercial software, and the heat transfer performance was discussed over dimensionless streamline and temperature contours, as well as quantified by average Nusselt numbers (Nu). The numerical outcomes revealed that the curvature of side walls have significant effects on buoyancy-driven fluid flow and heat transfer. The fluid flow was squeezed and restricted in concave enclosures, particularly at high Ra, while double longitudinal circulations were generally formed in convex enclosures. Hence, utilization of concave enclosures led to a significant decrease in Nu, approaching 45%, while the convex-shaped enclosures resulted in a remarkable improvement in Nu, which can reach up to 18.6% depending on the Ra, compared to the reference enclosure. Regarding the outcomes of the work, convex-structured enclosures were found to be superior for enhancing heat transfer and were recommended for engineering applications such as cooling of electronics, solar thermal energy and relevant heat exchangers.

Anahtar Kelimeler

Concave , Convex , Enclosure , Heat transfer enhancement , Natural convection

Kaynakça

• [1] Kandeal AW, Ismail M, Basem A, Elsayad MM, Alawee WH, Majdi HS, Abdullah AS, Jang SH, An M, Omara ZM, Ghazaly NM, Sharshir SW. An overview of the improvement of natural convection heat transfer via surface thermal radiation for different geometries. Results in Engineering 2024; 23: 102514.
• [2] Hussain Z, ul ain N, Ullah N, Nisar Z, Anwar MS. Influences of natural convection on cylindrical objects within a square enclosure with varied shapes. Case Studies in Thermal Engineering 2025; 74: 106772.
• [3] Rahimi A, Dehghan Saee A, Kasaeipoor A, Hasani Malekshah E. A comprehensive review on natural convection flow and heat transfer. International Journal of Numerical Methods for Heat and Fluid Flow 2019; 29: 834–877.
• [4] Venkatadri K, Anwar Bég O, Rajarajeswari P, Ramachandra Prasad V. Numerical simulation of thermal radiation influence on natural convection in a trapezoidal enclosure: Heat flow visualization through energy flux vectors. International Journal of Mechanical Sciences 2020; 171: 105391.
• [5] Tayebi T, Öztop HF. Entropy production during natural convection of hybrid nanofluid in an annular passage between horizontal confocal elliptic cylinders. International Journal of Mechanical Sciences 2020; 171: 105378.
• [6] Al-Mudhafar AHN, Nowakowski AF, Nicolleau FCGA. Performance enhancement of PCM latent heat thermal energy storage system utilizing a modified webbed tube heat exchanger. Energy Reports 2020; 6: 76–85.
• [7] Giwa SO, Sharifpur M, Ahmadi MH, Meyer JP. Magnetohydrodynamic convection behaviours of nanofluids in non-square enclosures: A comprehensive review. Mathematical Methods in the Applied Sciences 2020; https://doi.org/10.1002/mma.6424.
• [8] Bawazeer SA, Alsoufi MS. Natural convection in a square cavity: Effects of Rayleigh and Prandtl numbers on heat transfer and flow patterns. Case Studies in Thermal Engineering 2025; 73: 106680.
• [9] Afsana S, Molla MM, Nag P, Saha LK, Siddiqa S. MHD natural convection and entropy generation of non-Newtonian ferrofluid in a wavy enclosure. International Journal of Mechanical Sciences 2021; 198: 106350.
• [10] Parvin S, Chamkha AJ. An analysis on free convection flow, heat transfer and entropy generation in an odd-shaped cavity filled with nanofluid. International Communications in Heat and Mass Transfer 2014; 54: 8–17.
• [11] Yıldız Ç, Yıldız AE, Arıcı M, Azmi NA, Shahsavar A. Influence of dome shape on flow structure, natural convection and entropy generation in enclosures at different inclinations: A comparative study. International Journal of Mechanical Sciences 2021; 197: 106321.
• [12] Miroshnichenko IV, Sheremet MA, Oztop HF, Abu-Hamdeh N. Natural convection of Al2O3/H2O nanofluid in an open inclined cavity with a heat-generating element. International Journal of Heat and Mass Transfer 2018; 126: 184–191.
• [13] Ji C, Qin Z, Dubey S, Choo FH, Duan F. Simulation on PCM melting enhancement with double-fin length arrangements in a rectangular enclosure induced by natural convection. International Journal of Heat and Mass Transfer 2018; 127: 255–265.
• [14] Mahdi JM, Nsofor EC. Melting enhancement in triplex-tube latent thermal energy storage system using nanoparticles-fins combination. International Journal of Heat and Mass Transfer 2017; 109: 417–427.
• [15] Kumar S, Mahapatra SK. Natural convection in open square enclosure with different heat source sizes. Heat Transfer Engineering 2024; 45: 1190–1205.
• [16] Mote Gowda KGB, Rajagopal MS, Aswatha, Seethramu KN. Numerical studies on natural convection in a trapezoidal enclosure with discrete heating. Heat Transfer Engineering 2020; 41: 595–606.
• [17] Natarajan E, Basak T, Roy S. Natural convection flows in a trapezoidal enclosure with uniform and non-uniform heating of bottom wall. International Journal of Heat and Mass Transfer 2008; 51: 747–756.
• [18] Hemmat Esfe M, Abbasian Arani AA, Yan WM, Ehteram H, Aghaie A, Afrand M. Natural convection in a trapezoidal enclosure filled with carbon nanotube–EG–water nanofluid. International Journal of Heat and Mass Transfer 2016; 92: 76–82.
• [19] Rahaman MM, Bhowmick S, Saha SC. Thermal performance and entropy generation of unsteady natural convection in a trapezoid-shaped cavity. Processes 2025; 13: 921.
• [20] Rahaman MM, Bhowmick S, Saha SC. Unsteady natural convection and entropy generation in thermally stratified trapezoidal cavities: A comparative study. Processes 2025; 13: 1908.
• [21] Rahaman MM, Bhowmick S, Pada Ghosh B, Xu F, Nath Mondal R, Saha SC. Transient natural convection flows and heat transfer in a thermally stratified air-filled trapezoidal cavity. Thermal Science and Engineering Progress 2024; 47: 102377.
• [22] Bilal S, Rehman M, Noeiaghdam S, Ahmad H, Akgül A. Numerical analysis of natural convection driven flow of a non-Newtonian power-law fluid in a trapezoidal enclosure with a U-shaped constructal. Energies 2021; 14: 5355.
• [23] Mehryan SAM, Ghalambaz M, Kalantar Feeoj R, Hajjar A, Izadi M. Free convection in a trapezoidal enclosure divided by a flexible partition. International Journal of Heat and Mass Transfer 2020; 149: 119186.
• [24] Selimefendigil F. Natural convection in a trapezoidal cavity with an inner conductive object of different shapes and filled with nanofluids of different nanoparticle shapes. Iranian Journal of Science and Technology, Transactions of Mechanical Engineering 2018; 42: 169–184.
• [25] Prince HA, Rozin EH, Sagor MJH, Saha S. Evaluation of overall thermal performance for conjugate natural convection in a trapezoidal cavity with different surface corrugations. International Communications in Heat and Mass Transfer 2022; 130: 105772.
• [26] Dutta S, Kumar P, Kalita JC. Streamfunction-velocity computation of natural convection around heated bodies placed in a square enclosure. International Journal of Heat and Mass Transfer 2020; 152: 119550.
• [27] Lasfer K, Bouzaiane M, Lili T. Numerical study of laminar natural convection in a side-heated trapezoidal cavity at various inclined heated sidewalls. Heat Transfer Engineering 2010; 31: 362–373.