Stable Numerical Calculation of Critical Flow


                          Jovan Stefanovski

                              Abstract
     In the neighborhood of the points in the flow field in open canal whe-
re critical flow occurs, stability of each numerical scheme becomes proble-
matic. The goal of this paper  is to give  a stable numerical algorithm for
stationary and nonstationary one-dimensional flow which successfully solves
subcritical, supercritical  as well as  critical flow. The stability of the
numerical algorithm is verified only by numerous numerical examples and not
exactly, becouse critical flow is inherently nonlinear process as it is mo-
delled by the pair of Saint - Venan partial differential equations  but the
methods  for obtaining the stability limits of numerical schemes in the li-
terature (Furier's method,for example) may be applied to linear or lineari-
zed mathematical models only.