FRICTION-TERM RESPONSE TO BOUNDARY-CONDITION TYPE IN FLOW MODELS

The friction-slope term in the unsteady open-channel flow equations is examined using two numerical models based on different formulations o f the governing equations and employing different solution methods. Th e purposes of the study are to analyze, evaluate, and demonstrate the behavior of the term in a set of controlled numerical experiments usin g varied types and combinations of boundary conditions. Results of num erical experiments illustrate that a given model can respond inconsist ently for the identical resistance-coefficient value under different t ypes and combinations of boundary conditions. Findings also demonstrat e that two models employing different dependent variables and solution methods can respond similarly for the identical resistance-coefficien t value under similar types and combinations of boundary conditions. D iscussion of qualitative considerations and quantitative experimental results provides insight into the proper treatment, evaluation, and si gnificance of the friction-slope term, thereby offering practical guid elines for model implementation and calibration.