Author(s): Seongeun Choi, Jin Hwan Hwang
Linked Author(s): Jin Hwan Hwang
Keywords: LCS; OpenFOAM; Particle; The Stokes number;
Abstract: A numerical simulation is used to compare the particle dispersion of flows around a circular cylinder. The dispersion depending on various characteristics of particles, such as diameter and density, are investigated here. To explain particle properties, the dimensionless number, the Stokes number, is used. The flow Reynolds number is 200 and the diameter of particle change satisfying the Stokes number, 0.02, 0.1 and 0.5. It is the ratio of the characteristic time of particle to the characteristic time. In this study, an open source computational simulation tool, OpenFOAM is used to calculate flow structure and the particle position over time. The computation domain is meshed by rectangular grid and the vegetation is of straight and rigid cylinders. After getting the velocity vector of flow, this work applies an accurate technique, Lagrangian Coherent Structure(LCS), in order to understand the particle dispersion in the flow. LCS is constructed with the finite-time Lyapunov exponent(FTLE), which was obtained by post-processing velocity fields. The FTLE
field is the changed distance of neighboring particle trajectories over a given time interval, so it integrates
these position forward and backward in time. After getting LCS lines, the location of particles is marked to verify distribution regarding to the diameter. In addition, flow pattern and the stagnation point are investigated.