High-speed computation and saving memories for Zielke's method to simulate frequency-dependent friction in laminar liquid pipe flow.

A method combining characteristics and finite difference was developed by Zielke to predict a transient phenomena of a fluid transmission line. This method is easy to apply to complicated systems and has high accuracy and is, therefore, used frequently. However, it requires enormous computation time and huge computer storage to simulate frequency-dependent friction in transient liquid flow. In order to counteract these disadvantages, the authors paid attention to the fact that the weighting function which causes the above problems, is composed of two parts, i.e. the part expressed by exponential functions and the part expressed by other functions. In order to perform the mathematically identical calculation without approximations, a new method has been developed which requires much less computation time and computer storage than the conventional method. The operation has become easy by showing the calculation process as a block diagram for a digital filter because this calculation is the same as the calculation of a digital filter.