Solving ordinary differential equations I (2nd revised. ed.): nonstiff problems
Solving ordinary differential equations I (2nd revised. ed.): nonstiff problems
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A novel partitioned algorithm able to solve ODEs arising from transient structural dynamics is presented. The spatial domain is partitioned into a set of disconnected subdomains owing to computational or physical considerations, and continuity conditions of velocity at the interface are modelled using a dual Schur formulation, where Lagrange multipliers represent reaction forces. Interface equations along with subdomain equations lead to a system of DAEs for which an interfield parallel procedure is developed. The algorithm solves interface Lagrange multipliers, which are subsequently used to advance the solution in subdomains. The proposed coupling algorithm that enables arbitrary Generalized-@a schemes to be coupled with different time steps in each subdomain is an extension of a method originally proposed by Pegon and Magonette. Thus, subcycling permitting to deal also with stiff and nonstiff subsystems is allowed. In detail, the paper presents the convergence analysis of the novel interfield parallel scheme for linear single- and two-degrees-of-freedom systems because a multi-degrees-of-freedom system is too difficult for a mathematical treatment. However, the insight gained from the analysis of these coupled problems and the consequent conclusions are confirmed by means of numerical experiments on a four-degrees-of-freedom system.