Some potential problems are studied by applying boundary element method.The starting equation in the form of discretization is obtained by weighting residual.The computer software for numerical simulation has been provided.Numerical results conform to physics law and are satisfactory.

With boundary element method^[1,2], this paperdeals with blood flow in the blood-vessel of lung. From the numerical simulation for the sheet fluid of SFH model and SFH model in the blood-vessel of lung, the velocity field of blood fluid, the distribution of surface force and pressure on the surface of the blood-vessel are given. The result shows that the stress suppressed on the skin cell of the lung blood-vessel is in the range from 0 to 4.48×10^-5N/cm². This is well consistent with Dewey's experimental result. Also the computational result shows that the formation of lung cell helps the breathing membrane supPOrt the smallest stress. Meanwhile, the method used in this paper provides an efficient approach to numerical analysis of the blood flow in the heart and blood vessel.

The results of water hammer for multi-piping system is presented the water hammer in complicated pipes has been computed by characteristic line-method. To improve the accuracy of numerical calculations, Variable step with multipipes are used. So the computational work are greatly reduced. Some computable results are satisfactory. It will provide the foundation to choose plan for piping desin and piping protection.