'Periodica Polytechnica Budapest University of Technology and Economics'
Abstract
The computation of wave phenomena belongs to the subject of the unsteady
flow problems. To the computations boundary conditions are required. The
initial conditions, usually, can be very easily produced. Generally, the
upstream boundary condition is given, and this presents the actual wave for
the effected and calculated lower river stretch.
It is a general and difficult problem to produce the downstream boundary
condition - especially for shorter river stretches - which is often
substituted
by the normal (steady flow) discharge curve: Q0=Q0(h). This approach -
depending on the type of the flood wave - is very often not precise enough.
The goal of this study is to justify that the downstream boundary condition,
instead of the Q0=Q0(h) discharge curve, can be substituted by the
Q=Q(h) loop, which is also a rating curve, but for unsteady flow.
The computational results justified the statements of the authors. It was also
numerically justified, that during a total wave flow the maximum time order
of the main hydraulic parameters is: Smax, vmax, hmax (or
Zmax) and Qmax