Fluid–structure interaction and thermal performance: a numerical study on crossflow heat exchangers with aerodynamically optimised splitter elements

The thermohydraulic performance of backwards-facing splitter plates with different L/D ratios in a crossflow heat exchanger under fully developed turbulent flow at Reynolds numbers between 5500 and 14,500 is examined numerically in this study. While velocity streamlines, static pressure contours, and turbulent kinetic energy distributions show vortex formation, wake suppression, and enhanced near-wall mixing mechanisms, simulations using 3D and 2D models validate against experimental data with maximum deviations of 14% and 12% for Nusselt number (Nu) and friction factor (f), respectively. With optimal L/D ratios balancing heat transfer gains against pressure drop penalties, the splitter plates significantly enhance convective heat transfer through flow reattachment and secondary vortices, while maintaining performance evaluation criteria (PEC = (Nu/Nu₀)/(f/f₀)^{1/3}) greater than one across all configurations. Longer plates yield superior PEC at moderate Re because of effective boundary layer control. These results provide applicable design guidelines for compact heat exchangers in industrial thermal management applications that require improved heat dissipation within limited pumping power budgets, by establishing quantitative relationships between splitter geometry, flow regime, and thermohydraulic efficiency.