A way to explain the thermal boundary effects on laminar convection through a square duct

• Published in: Frontiers in Energy Vol. 4; no. 4; pp. 496 - 506
• Main Authors: WANG, Liangbi, GAI, Xiaoping, HUANG, Kun, ZHANG, Yongheng, YANG, Xiang, WU, Xiang
• Format: Journal Article
• Language: English
• Published: Heidelberg Higher Education Press 01.12.2010; SP Higher Education Press; Springer Nature B.V
• Subjects: Boundaries; Boundary conditions; Boundary layer; Convection; convective transport; Ducts; Energy; Energy conservation; Energy Systems; Flow velocity; Fluctuations; Fluid dynamics; Heat flux; Heat transfer; Laminar; laminar flow; mass transfer; Mathematical analysis; Numerical analysis; Research Article; Reynolds number; Studies; thermal boundary effects; Topological manifolds; Velocity; Walls; laminar flow; thermal boundary effects; convective transport; heat transfer; mass transfer
• ISSN: 2095-1701; 1673-7393; 2095-1698; 1673-7504
• DOI: 10.1007/s11708-010-0020-2

A way using the reformulation of the energy conservation equation in terms of heat flux to explain the thermal boundary effects on laminar convective heat transfer through a square duct is presented. For a laminar convection through a square duct, it explains that on the wall surface, the velocity is zero, but convection occurs for uniform wall heat flux (UWHF) boundary in the developing region due to the velocity gradient term; for uniform wall temperature (UWT) boundary, only diffusion process occurs on the wall surface because both velocity and velocity gradient do not contribute to convection; for UWHF, the largest term of the gradient of velocity components (the main flow velocity) on the wall surface takes a role in the convection of the heat flux normal to the wall surface, and this role exists in the fully developed region. Therefore, a stronger convection process occurs for UWHF than for UWT on the wall surface. The thermal boundary effects on the laminar convection inside the flow are also detailed.