Visualization of steady streaming near oscillating spheroids

Experimental studies of steady streaming flows are presented for spheroids of various aspect ratios oscillating in a viscous fluid along their axis of symmetry at Reynolds numbers up to 150 and normalized oscillation amplitudes up to 1.2. The steady streaming component of the flow is visualized using phase-locked particle pathline images along the central plane of the spheroid. The extent of the inner region of the flow, characterized by the distance to the stagnation points, appears to depend on a length scale based on the spheroid aspect ratio and equivalent radius. Spheroids were also oscillated at a nonzero angle with respect to their axis of symmetry. The angular displacement of the stagnation points on the surface of these obliquely oscillated spheroids is related to the aspect ratio and the angle of oscillation.