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 mm 2 ) 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.