Characterizing the time dependent deposition of particles in a channel flow using optical coherence tomography

[Graphical abstract presents]

Understanding particle transport and deposition dynamics in confined flow regions is crucial for optimizing computational models and processes (e.g., filtration). However, the lack of suitable experimental methods to measure dynamic deposition has limited the ability to fully characterize transient deposition behavior. In this study, we present a high-resolution optical coherence tomography (OCT) technique to assess dynamic particle deposition characteristics in a particle-laden flow. The impact of flow rate, channel surface and particle properties were studied in a square channel using a pharmaceutical fine grade lactose powder (LH300, Dv50 = 5 μm) and a coarser grade lactose (SV010, Dv50 = 109 μm). Results showed a rapid increase in mean deposition thickness during the initial phase (<2 s) of flow, followed by a relatively steady deposition thickness. At the downstream region, deposition rate of LH300 was significantly higher at 15 LPM compared to 30 LPM (p = 0.014) and 45 LPM (p = 0.027). At the entrance region, however, no significant variation in deposition rate with flow rate was observed, potentially due to the strong mixing effect of the still-developing flow profiles. The influence of particle size was evident, with SV010 showing a more closely spaced deposition clusters and higher deposition volume than LH300. The findings highlight the technique's potential to characterize dynamic deposition in two-phase flow, a functionality that holds promise for various applications.