Abstract
Circular cylinders, flat plates or a rigid wavy wall was fixed on the bottom floor of a water tank.
When the fluid in the tank was performed in sinusoidal oscillations along the floor, the secondary flows induced around the ridges were investigated experimentally by means of flow visualization techniques.
In the case of a single ridge, another circulatory streaming is induced near the bottom floor besides what is called the inner one and the outer.
In the case of several ridges at regular gaps, there exist two circulatory streamings in each gap.
