부산대학교 도서관

Fluid flow around the sphere is widely used in industrial systems, in which the hydrodynamic and heat transfer performances play a key role in energy consumption. The flow and heat transfer characteristics around the sphere are greatly dependent on the shedding and development of vortices. In the present paper, the fluid flow and heat transfer around the smooth sphere are investigated with the LES method. The results show that along the flow direction, the leeward region of the sphere alternately produces up and down-shedding vortices. Vortex shedding causes local pressure changes, resulting in changes in flow and heat transfer performance. The Cd, CL, and Nu fluctuate around a stable value. The frequency and amplitude of the fluctuation increase significantly as the inlet flow rate increases. Especially, the maximum changes in Cd are 6.26 % and 22.79 % when Q = 1 and 6 m3/h. The frequency of vortex shedding increases by about 2.6 times when the flow rate increases from 2 m3/h to 5 m3/h. In addition, the vortex shedding from the leeward region moves downstream with more energy due to the increase in frequency, which leads to more cold fluid participating in heat transfer.