Thermal Performance Enhancement in Wavy Enclosures Using Strategically Positioned Rectangular Blocks under Periodic Heating Conditions for Thermal Management Applications

Hossain, Md. Aslam; Rahman, Md Shohanur; Mishu, Marzia Akter; Rahman, Md. Azizur; Islam, G.M. Zahidul; Hossain, Md. Rezvi; Mehejabin, Aftara

doi:10.22055/jacm.2026.49568.6081

Thermal Performance Enhancement in Wavy Enclosures Using Strategically Positioned Rectangular Blocks under Periodic Heating Conditions for Thermal Management Applications

Articles in Press

Document Type : Research Paper

Authors

Md. Aslam Hossain ¹

Md Shohanur Rahman ²

Marzia Akter Mishu ²

Md. Azizur Rahman ²

G.M. Zahidul Islam ³

Md. Rezvi Hossain ²

Aftara Mehejabin ²

¹ Department of Mathematics, Pabna University of Science and Technology, Pabna-6600, Bangladesh.

² Department of Mathematics, Pabna University of Science and Technology, Pabna-6600, Bangladesh

³ General Education Department, University of Global Village, Barishal-8200, Bangladesh.

10.22055/jacm.2026.49568.6081

Abstract

Natural convection in enclosures with internal obstructions is central to thermal-management applications such as electronic cooling, solar receivers, and compact heat exchangers. This study numerically examines two-dimensional, steady laminar buoyancy-driven flow and heat transfer in a wavy square cavity containing a rectangular block at upper-left, center, and upper-right positions. The block is maintained at the cold reference temperature in Case I and at the hot reference temperature in Case II. The left and bottom wavy walls are subjected to periodic cosine temperature conditions, the right wavy wall is cold, and the top wall is adiabatic. The finite-element model is solved in COMSOL Multiphysics for Ra = 10³–10⁵ and Pr = 0.2, 0.71, and 10. Quantitative validation against published experimental data gives mean deviations of 4.97% and 3.93% on the two lateral walls. At the center position and Pr = 0.71, the dimensionless cut-line velocity magnitude increases from 0.3687 to 30.2837 in Case I and from 0.8110 to 34.9649 in Case II as Ra increases from 10³ to 10⁵. At Ra = 10⁴ on the bottom wavy wall, changing the block from cold to heated at the coordinate-matched center position increases the average Nusselt number by 1.93-1.96%; the coordinate-matched upper-left change is marginal (-0.31% to -0.74%), while the case-specific upper-right configurations differ by -1.87% to -2.06%. These results show that block placement redistributes plume trajectories, recirculation, and wall-normal thermal gradients, so the preferred placement depends on the thermal-management objective rather than on a universal optimum.

Keywords

Natural convection

Wavy Square cavity

Rectangular block

Nusselt number

Finite element method

Subjects