작은 밀도차를 갖는 구형입자의 추종성에 관한 연구

Study on the Traceability of Spherical Particles with Small Density Difference

Numerical and experimental study on the traceability of small spherical particles in a flow field were performed when the particles have 2% lower density compared with the fluid. Equations of single particle motion, including Saffman lift and Basset force are formulated. A flow field for the application of the equations is obtained by numerical calculation of the 2-D cavity flow. As a result, the center of particle motion deviates greatly from the center of cavity primary vortex, and particles distributed within the secondary eddies disappear by the buoyancy effect. In experimentation, PIV (Particle Imaging Velocimetry) was adopted for two Re numbers 3.2x10³, 10⁴ and also for two particle sizes range 0.5-0.7 mm, 0.7-0.8 mm in diameter. The center of particle motion moves right-upward and its velocity component to the gravitational direction reveals buoyancy effect and its effect is greater in case of the larger particle with smaller Re number.