Using BEM to solve vibrating or unsteady Stokes flow is very attractive. At first we derive the Green functions for 2D and 3D. Then we deduce the relative formula, the explicit expression for pressure and the boundary integral equation. The integral equation is discretized into a set of linear algebric equations. In the case of 2D, the influence coefficients of the segment to itself are integrated analytically. In order to check such BEM, an example with analytical solution already exists is solved numerically. The result shows that the method based upon our Green functions is perfect.

A hybrid method [1] is used to solve the wave of 3-D low Reynolds flow in an elastc pipe. The flow region is divided into far field and near fielf. In far field the solutions can be expressed by series expansions[2], while in the near field FEM could be used. 3-D eigen-functions must be taken into account. The corresponding eigen values are calculated numerically. It is shown that except the fundamental eigen functions which are just the 2-D ones, the others decrease very quickly. So 2-D eigen functions are enough for many cases.