Abstract
Tracer methods have been frequently applied to know flow patterns in flow visualization technique.
Recently, they have been applied not only to know qualitative flow patterns, but also to know some flow quantities through the measurements of tracer velocities under the remarkable development of computers and image processing techniques in a decade. In this stage, it becomes important to know the response of a tracer particle to rapid change of flow velocity like as in turbulent flow.
The step response of a tracer particle is discussed analytically in this paper, by the use of Tchen's equation of motion, including the Basset history term which has the important role in high rate acceleration.
