Geometric Optimization of Corrugated Channels for Heat Transfer Enhancement Using Field Synergy and Response Surface Methodology

This study presents a numerical investigation of turbulent flow and heat transfer in corrugated channels, focusing on the effects of key geometric parameters on thermal–hydraulic performance. The corrugation height-to-channel height ratio (C/H), the length ratio (L1/L2), and the expansion angle (θ) were systematically varied, and simulations were performed for Reynolds numbers between 4 × 103 and 1 × 104 using water as the working fluid and SST k–ω turbulence model. Response Surface Methodology (RSM) was applied to develop predictive models for the Nusselt number (Nu), friction factor (f), and thermal performance index (η). The results indicate that C/H is the dominant geometric parameter controlling both heat transfer and flow resistance. Increasing C/H from 0.10 to 1.00 results in a reduction in Nu of approximately 20–22%, while the friction factor decreases by about 40–45% over the investigated Reynolds number range, revealing a clear thermal–hydraulic trade-off. In contrast, variations in L1/L2 (0.5–6.0) and θ (5–30°) have a relatively weak influence, typically causing changes in Nu and f below 5–7%. The thermal performance index remains consistently above unity for all configurations and varies within a narrow range (η ≈ 1.00–1.16). The maximum thermal enhancement of approximately 10–15% is achieved at lower C/H values, particularly at low Reynolds numbers, whereas higher C/H values favor reduced pressure losses. Overall, the findings quantitatively demonstrate that corrugation height governs the thermal–hydraulic behavior of corrugated channels, while L1/L2 and θ provide design flexibility with minimal performance penalty.