F41.pdf (319.52 kB)
CCWI2017: F41 'Why are Line Search Methods Needed for Hydraulic DDM and PDM Solvers?'
journal contributionposted on 2017-09-01, 15:23 authored by Olivier Piller, Sylvan Elhay, Jochen Deuerlein, Angus Simpson
It is common that non-convergence problems occur for simulations under normal or abnormal operations. Among the main causes, there are the use of sublinear functions for calculation of the hydraulic steady-state, some derivative issues and an ill-conditioned iteration matrix in the solution method. The objective of this paper is to specify non-convergence cases for existing hydraulic software solutions. The damped Newton solution together with regularization techniques are proposed for ensuring global convergence, whatever the initial solution. Failures of convergence are shown to exist even on small case studies.