Abstract
Recently, there are so many researches and developments in order to design micro machines that inspect and operate in blood vessels. The vessel wall influences fluid flow that affects the motion of micro machines. It is important to clarify the fluid-solid interaction in case of small clearance between a micro machine and the vessel wall to design micro machines with enough reliability. This research investigates the motion of a sphere and fluid flow in a narrow tube under the constant external force of gravity acceleration parallel to the pipe axis.
