Application of Refractive Index-Matching to Investigate the Dynamics of Solid Particles Moving Through Constricted or expanding Pipelines

In this study, we use a sodium iodine solution to conduct refractive index-matched experiments, studying the dynamics of solid particles moving through pipelines with variable geometries, including constrictions and expansions. Our research targets a base flow field with a Reynolds number ranging from 10^3 to 10^5. Traditional methodologies often struggle to accurately capture the intricate interaction between solid particles and flow alterations due to changes in conduit geometry. Our research addresses this challenge by implementing a refractive index-matching approach that minimizes optical distortions, enabling high-speed tomographic measurements of both solid particle motion and flow field using particle tracking velocimetry.

We constructed a closed-loop water tunnel with an optically accessible round cross section test section machined with interchangable contracting or expanding geometry. Solid acrylic spheres of substantial size (3-12mm in diameter) were introduced into the flow upstream, and their movement through the varying geometry was recorded. In our forthcoming presentation, we will detail our experimental design, compare flow field statistics with and without the spheres, and discuss the dynamics of the spheres as they navigate through the changing pipeline geometry. Our preliminary results indicate that this technique offers valuable insights into the behavior of particulate flow within constricted or expanding pipelines.