FINITE-ELEMENT MODEL FOR HIGH-VELOCITY CHANNELS

Numerical modelers of high-velocity channels are faced with supercriti cal transitions and the difficulty in capturing discontinuities in the flow field, known as hydraulic jumps. The implied smoothness of a num erical scheme can produce fictitious oscillations near these jump loca tions and can lead to instability. It is also important that the discr ete numerical operations preserve the Rankine-Hugoniot conditions and accurately model jump speed and location. The geometric complexity of high-velocity channels with bridge piers and service ramps are easily represented using an unstructured model. A two-dimensional finite-elem ent model that utilizes a characteristic based Petrov-Galerkin method and a shock-detection mechanism, which relies on elemental energy vari ation results in a robust system to model high-velocity channels. Comp arisons are made between analytic shock-speed results, published labor atory data of a lateral contraction, and with a more general physical model.