Near field vortex dynamics in axially forced, laminar, co-flowing jets: a descriptive study of the flow configurations

Passive flow control of bileaflet mechanical heart valve leakage flow

“…It was shown that even two tabs could significantly increase mixing to sufficiently reduce the potential core length and increase the decay of the centerline velocity, thereby increasing jet spreading and reducing the flow shear. In later investigations, streamwise vorticity generation at the jet exit was promoted by enforcing azimuthal excitation through VGs or tabs at the edge of the nozzle (Ahuja and Brown, 1989;Zaman and Foss, 1997;Zaman et al, 1994) or by using corrugated, lobed, or indented nozzle edges (Lecuona et al, 2002;Rodriguez-Aumente et al, 2001). While several configurations of passive flow control devices offer attractive opportunities for controlling blood flow in cardiovascular systems, the use of VGs for controlling mixing within jets is of specific relevance to BMHVs as evident from the strong impact of even a small number of tabs on jet flows (Bradbury and Khadem, 1975).…”

“…Such changes in the shear stresses can be realized by small alterations of the velocity field using passive, miniature flow control elements that are integrated onto the surfaces exposed to flow. The utilization of these flow control devices for the manipulation of turbulent shear flows has been extensively investigated in a variety of traditional mechanical and aerospace applications (Ahuja and Brown, 1989;Bradbury and Khadem, 1975;Choi et al, 1993;Lecuona et al, 2002;Lin, 2002;Moin and Kim, 1997;Rodriguez-Aumente et al, 2001;Zaman and Foss, 1997;Zaman et al, 1994). In this paper we examine the approach of passive flow control integrated into the valve leaflet surface in reducing mechanical loads experienced by blood elements.…”