Enhanced heat transfer in a tube with fish scale bionic rib

To address the challenge of balancing heat transfer enhancement and flow resistance in heat exchangers, this study introduces a novel bionic approach by integrating fish scale geometry with shark skin split seam structures. The novelty lies in the design of two innovative rib configurations: the N-SS (no split seam) fish scale bionic rib and the W-SS (with split seam) rib, which synergistically combine biological inspiration with multi-longitudinal swirls (MLSs) to optimize thermo-hydraulic performance. Numerical simulations demonstrate that the W-SS rib generates intensified MLSs, achieving 2.19 times higher Nusselt number (Nu), while maintaining superior swirl intensity and turbulent kinetic energy. Key findings reveal that reducing rib pitch (p = 10 mm) and increasing rib area (A = 28 mm2) maximize the performance evaluation criterion (PEC = 1.46 at Re = 8475) of the W-SS enhanced tube. Empirical correlations for Nu and friction factor (f) are established with deviations below +/- 6% and +/- 8%, respectively, offering direct applicability for industrial heat exchanger optimization.