Probabilistic Investigation of Cavitation Occurrence on Morning-Glory Spillways Using Numerical Modeling and Response Surface Method

Abstract

Estimating the cavitation damage to morning-glory spillways is quite important due to the uncertainties that affect cavitation (e.g., high velocity, negative flow pressure, etc.). This paper aims to develop the model uncertainties to address the reliability assessment of the cavitation damage to different points of the Haraz Dam morning-glory spillway in Iran. As an explicit limit state function was lacking to determine the cavitation reliability, 35 samples were produced based on the statistical features, probability distribution and inter-correlation of the uncertainties. Using the Latin Hypercube Simulation (LHS) method and Shapiro-Wilk Test, the cavitation response was found for them through the ANSYS Fluent-3D numerical model analyses, and the implicit LSF was created for 4 critical points on the morning-glory spillway. To do so, the Response Surface Method (RSM) was utilized to generate the explicit LSF and the reliability of the cavitation damage was estimated using the Monte Carlo and first and second order reliability methods. The obtained results show that P4, with pf > 80%, is the most critical overflow point whereas the lowest RMSE is between SORM and MCS method.

Keywords

• morning-glory spillway
• cavitation reliability
• numerical modeling
• implicit/explicit limit state function
• response surface method