Exponential Adams Bashforth integrators for stiff ODEs, application to cardiac electrophysiology
Résumé
Models in cardiac electrophysiology are coupled systems of reaction diffusion
PDE and of ODE. The ODE system displays a very stiff behaviour. It is non
linear and its upgrade at each time step is a preponderant load in the total
amount of computational cost. The issue is to develop high order explicit and
stable methods to cope with that situation.
In this article is analyzed the resort to exponential Adams Bashforth (\EAB)
integrators in cardiac electrophysiology. The method is presented in the
framework of a general and varying stabilizer, that is well suited in this
context. Stability under perturbation (or 0-stability) is proven. This
provides a new approach for the convergence analysis of the method. The
Dahlquist stability properties of the method is performed. It is presented in
a new framework that incorporates the discrepancy between the stabilizer and
the system Jacobian matrix. Provided this discrepancy is small enough, the
method is shown to be $A(\alpha)$-stable. This result is interesting for
an explicit time stepping method. Numerical experiments are presented for two
class of stiff models in electrophysiology, including performances comparisons
with several classical methods. The \EAB method is observed to be as stable as
implicit solvers and cheaper at equal accuracy level.
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