Background Nasal airway obstruction (NAO) from septal deviation and turbinate hypertrophy is a major cause of chronic nasal blockage and reduced quality of life. Septoplasty with inferior turbinoplasty is standard treatment, yet objective proof of physiological benefit remains limited. Computational fluid dynamics (CFD) enables detailed visualisation and quantification of intranasal airflow, resistance, and heat transfer. Methods In this prospective ethics-approved study, patients undergoing septoplasty with inferior turbinoplasty at a tertiary centre had pre- and 3-month postoperative CT scans converted into 3-D nasal airway models. CFD simulations were correlated with rhinomanometry, acoustic rhinometry, PNIF, and patient-reported outcomes (NOSE, VAS, SNOT-22). Key CFD metrics included nasal resistance, airflow velocity, mucosal surface temperature, and mucosal heat flux (MHF)—a surrogate of mucosal cooling and perceived patency. Results Postoperative models showed markedly improved laminar airflow, reduced regional resistance, and significantly higher MHF, especially at the internal nasal valve and inferior turbinate regions (p < 0.05). MHF correlated strongly with subjective patency improvement, while conventional parameters such as resistance and bulk flow correlated less well. CT and endoscopic findings confirmed anatomical correction, and CFD visualisations demonstrated enhanced convective heat transfer and smoother thermal gradients. Conclusions Septoplasty with inferior turbinoplasty improves nasal airflow not only by enlarging the airway but by restoring effective mucosal cooling. These findings support the mucosal thermoregulation theory of nasal patency. CFD-derived MHF appears the most sensitive and clinically relevant biomarker of surgical success, offering a new paradigm for functional assessment and preoperative planning in nasal surgery.