Large Eddy Simulation on the influence of Sharkskin structures on coherent structure evolution and heat transfer in heat exchange tubes

Bionics provides innovative inspiration for the design of heat exchange equipment. Although the excellent flow control and heat transfer characteristics of shark skin, arising from its unique micro-rib structures, have been widely recognized, their application in shell-and-tube heat exchangers remains insufficiently understood. In this study, a shark skin-inspired microstructured heat exchange tube was proposed, and the influence of the bio-inspired surface on coherent structure evolution and heat transfer in the shell-side flow domain of a tube bundle was investigated. A high-fidelity numerical framework combining Reynolds Averaged Navier Stokes (RANS) pre-calculation and Large Eddy Simulation (LES) was proposed; by utilizing the RANS-predicted Taylor microscale to guide mesh generation and the Minimal Flow Unit theory for turbulence initialization, this method achieved a turbulent kinetic energy resolution rate exceeding 99% in a single iteration, significantly reducing computational costs. In addition, the field synergy principle was introduced to analyze the coupled transport mechanism of momentum and heat. The results show that the diamond-shaped discontinuous micro-rib arrangement plays a dominant role in regulating near-wall vortex evolution and heat transfer, whereas the influence of specific rib morphology is comparatively limited. The rhombic arrangement promotes the formation of inter-rib vortex clusters and the lifting of streamwise vortices, thereby enhancing the synergistic transport of momentum and heat. At Re = 10000, the local peak Nusselt number increased by nearly six times compared to the smooth wall, and the near-wall peak vorticity magnitude and temperature-gradient magnitude increased by approximately 20%. This enhancement mechanism remains effective at Re = 60000. A high spatial correlation between the distributions of | ∇ × U | and | ∇ T | further confirms that heat transfer enhancement is coupled with intensified momentum transport. These findings provide high-fidelity physical insight into the thermal enhancement mechanism of shark skin-inspired surfaces and establish a mechanistic basis for the engineering design of biomimetic heat-transfer tubes. • The bio-inspired shark skin microstructure with a rhombic staggered rib. • The high-precision LES with low computational cost, achieving over 99% resolved turbulent kinetic energy, is based on the minimum flow unit theory and sinusoidal velocity streaks. • Synergistic momentum-thermal transport mechanism driven by vortex dynamics.