Wake of a spherical bubble or a solid sphere set fixed in a turbulent environment

The wake of a clean spherical bubble and that of a solid sphere set fixed on the axis of a turbulent pipe flow are studied using large-eddy simulation. Wake characteristics are analyzed for particle Reynolds numbers Re-P=500 and 200 (based on the particle diameter and centerline velocity in the pipe) and bulk Reynolds numbers Re=6000 and 20 000 (based on the pipe diameter and bulk velocity). The centerline velocity defect is found to decrease as x(-2), which is faster than in a laminar wake or in a turbulent axisymmetric wake in a quiescent environment. The half-width of the wake evolves as alpha x, where alpha is an increasing function of the external turbulence intensity. (C) 2006 American Institute of Physics.