This paper deals with the steady streaming flow caused by oscillating double circular cylinders in a circular region.

Pressure gradient of unsteady flow of fluid in eccentric annulus with the inner cylinder reciprocating axially;

Flow rate distribution of the unsteady flow of power law fluid in eccentric annuli with the inner cylinder reciprocating axially;

Numerical simulation of unsteady flow around propeller and rudder with additional thrust fin;

Applying the law of conservation of mass,movement theorem of steady flow, and applying the mathematical method of stream function with the consideration of the axis symmetry,the three components of velocity quantum of the flow are deduced in detail.

A method of semi-false transient to compute three dimensional steady flow was presented.

Methods: The steady flow model and the pulsating flow model in the ductworkin vitrowere established.

The number and distribution of the singular points of streamlines in the cross section of steady flow through a curved tube are discussed by using the method of topological structure analysis.

It is showed by Galilean transformation of Euler’s formula that the flow type offluid will be different in different reference systems．As Bernoulli’s equation is valid only inreference systems in which ideal fluid flows in steady flow type，it is important to select aproper inertiai reference system in dealing with hydrodynamics problems such as Magnus ef-fect.