Human inspiratory profiles modulate airflow–particle dynamics and powder deagglomeration in Turbuhaler: a CFD–DEM study

Human inspiratory profiles affect transient airflow in dry powder inhalers (DPIs), yet how such transient flow governs powder release and deagglomeration remains less understood than under constant-flow conditions. Here, human inspiratory profiles were incorporated in a coupled computational fluid dynamics–discrete element method (CFD–DEM) model of Symbicort Turbuhaler to investigate airflow–particle dynamics and powder deagglomeration. The inhalation profiles were characterized by peak inspiratory flow (PIF; 50–70 L min -1 ) and flow increase rate (FIR; 4–9 L s −2 ). The model was validated against transient airflow, particle release, and deagglomerated particle fraction. The results show that, during inhalation, particles were entrained from the reservoir and accelerated through the chamber and spiral insert, where strong swirling flow promoted particle redirection and impact. Powder release and deagglomeration occurred mainly during the early inhalation stage (<0.5 s), before peak flow was reached. Increasing PIF strengthened airflow–particle interactions. Higher FIR advanced the timing of powder activation and breakup, exposing particles to effective aerodynamic interactions during the main release window. Sensitivity analysis confirmed this distinction: PIF primarily controlled the intensity of particle dynamics, whereas FIR modulated their timing. In summary, inspiratory profiles modulate powder dispersion, and effective Turbuhaler performance requires both sufficient PIF and rapid FIR.