Ludwig Prandtl's envisage: elimination of von Karman vortex street with boundary-layer suction

The present study is a revisit to Ludwig Prandtl's elimination of von Karman vortex street behind a circular cylinder by using steady suction in the boundary layer. We show in particular the full-time vortex evolutions and vortex dynamics in the wake. The wind tunnel investigations are conducted at the Reynolds number (Re) of 2.0 x 10(4). Slot suction is implemented symmetrically on both lower and upper boundary layers of the cylindrical test model to modify the flow separation process and to eliminate the downstream vortex street. The boundary layer suction is described by the dimensionless momentum parameter of suction relative to the free-stream airflow. A high-speed particle image velocimetry system is employed in the present study to visualize the flow patterns and capture the wake dynamics of the natural and modified cylinders controlled with boundary-layer suction. Graphic abstract

Automated summary

This study revisited Ludwig Prandtl's method of using steady suction in the boundary layer to eliminate von Karman vortex street behind a circular cylinder. Wind tunnel experiments were conducted at a Reynolds number of 2.0 x 10(4), showing the evolution and dynamics of vortices in the wake. By symmetrically implementing slot suction on the lower and upper boundary layers of the cylindrical test model, the flow separation process was modified and the downstream vortex street was eliminated.