Investigating the Cavitation Damage of Morning-Glory Spillways under Uncertainty

Abstract Mathematical methods and data-driven numerical models have replaced classical methods such as cavitation number controlling, as the cavitation phenomenon in morning-glory spillways is nonlinear in nature and uncertain making its damage estimation difficult. This study has considered uncertainties in the model to assess the cavitation responses on different points of Haraz dam morning-glory spillway, Iran. The spillway passing flow was simulated using the ANSYS Fluent-3D numerical model and the results were compared with those of the experimental model developed by the Iran-Water Resource Research Institute; their agreement was acceptable. Statistical parameters and the probability density function (PDF) of the uncertainties were obtained using the Shapiro-Wilk test, simulations were done using the Latin hypercube sampling (LHS) method, analyses of the numerical model were performed through 35 simulations using the central composite design (CCD) for the uncertainties considering their correlation and cavitation damage responses related to 10 critical points on the spillway were predicted using the response surface methodology (RSM). Responses were linear, and second-order functions were obtained based on interactions among model uncertainties. Results indicated that the correlation among the data extracted from numerical models and RSM was acceptable, the maximum prediction error in the RSM was within the permissible limits and the highest association rate of uncertainty factors in the cavitation damage responses was related to the flow-field inflow velocity.