Practical aspects of applications to unsteady liquid flows

Problems arising from the practical application of mathematical models for unsteady liquid pipe flows are examined. It is pointed out that, in the interests of developing a manageable computer program, it is desirable to the 'method of specified time intervals' rather than a more general characteristics grid. In particular, the former method makes the handling of interval boundary conditions much simpler. A consequence of opting for a specified time step delta is that invariably the characteristic curves dx/dt = u + or - do not normally pass through the grid points. The use of interpolations to deal with this situation is examined along with a method which treats the odd length of fluid at the end of a pipeline as a lumped mass, or, if small, neglects it.