Instabilities in Rotating Cylinders

Drug injection via pre-filled syringes or vials is a prevalent method for administering medication or vaccines. The automated process of preparing these syringes can potentially introduce harmful particles during filling. To ensure patient safety, rigorous quality control measures are implemented. Detecting such particles involves rotating the syringes to induce low and then abruptly stopping to observe any residual motion indicating particle presence, akin to Stokes' first problem. Recent investigations focused on infinitely long cylinders provide idealised models. However, real-world syringes have end walls, introducing additional complexities. This project aims to numerically study flow characteristics during rotation initiation and cessation, particularly for smooth angular velocity profiles and finite cylinder scenarios. By addressing this relatively novel problem, the project seeks to establish foundational knowledge essential for enhancing injection safety protocols.