Finite element solution of nonlocal Cahn-Hilliard equations with feedback control time step size adaptivity

In this study, we evaluate the performance of feedback control-based time step adaptivity schemes for the nonlocal Cahn-Hilliard equation derived from the Ohta-Kawasaki free energy functional. The temporal adaptivity scheme is recast under the linear feedback control theory equipped with an error es...

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Bibliographic Details
Published in:arXiv.org 2020-09
Main Authors: Barros, Gabriel F, Côrtes, Adriano M A, Alvaro L G A Coutinho
Format: Article
Language:English
Subjects:
Computer simulation
Control systems
Control theory
Controllers
Energy conservation
Feedback control
Free energy
Performance evaluation
Predictive control
Proportional integral derivative
Time marching
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Summary:In this study, we evaluate the performance of feedback control-based time step adaptivity schemes for the nonlocal Cahn-Hilliard equation derived from the Ohta-Kawasaki free energy functional. The temporal adaptivity scheme is recast under the linear feedback control theory equipped with an error estimation that extrapolates the solution obtained from an energy-stable, fully implicit time marching scheme. We test three time step controllers with different properties: a simple Integral controller, a complete Proportional-Integral-Derivative controller, and the PC11 predictive controller. We assess the performance of the adaptive schemes for the nonlocal Cahn-Hilliard equation in terms of the number of time steps required for the complete simulation and the computational effort measured by the required number of nonlinear and linear solver iterations. We also present numerical evidence of mass conservation and free energy decay for simulations with the three different time step controllers. The PC11 predictive controller is the best in all three-dimensional test cases.
ISSN:2331-8422