Large Eddy Simulation of Turbulent Flow Over a Sphere Using an Immersed Boundary Method
Abstract
Large eddy simulation of turbulent flow over a sphere is conducted at two different Reynolds numbers (Re = 3700 and 10(exp 4)) based on the free-stream velocity and the sphere diameter, in order to investigate the flow characteristics over the sphere. The present numerical method is based on a newly developed immersed boundary method in a cylindrical coordinate (Kim et al. 2001). Also, a hybrid numerical method of eliminating 2-delta waves in laminar accelerating flow region and also avoiding numerical dissipation in turbulent flow region is newly proposed for large eddy simlation of turbulent flow over a bluff body. At Re=3700, the shear layer is elongated in the streamwise direction to form a cylindrical vortex sheet and its instability begins to appear at x approximately equal 2d. Also, the flow behind the sphere is nearly laminar at x < d and contains few vortices. On the other hand, at Re = 10(exp 4), the shear layer instability occurs right behind the sphere in the form of vortex tube and the flow becomes turbulent in the near wake. Therefore, at Re = 10(exp 4) the size of the recirculation region is smaller and the wake recovers more quickly than at Re = 3700.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 2001
- Accession Number
- ADP013695
Entities
People
- Dongjoo Kim
- Haecheon Choi
Organizations
- Seoul National University