The candy wrapper problem - a temporal multiscale approach for pde/pde systems

We describe a temporal multiscale approach for the simulation of long-term processes with short-term influences involving partial differential equations. The specific problem under consideration is a growth process in blood vessels. The \emph{Candy Wrapper Process} describes a restenosis in a vessel that has previously be widened by inserting a stent. The development of a new stenosis takes place on a long time horizon (months) while the acting forces are mainly given by the pulsating blood flow. We describe a coupled pde model and a finite element simulation that is used as basis for our multiscale approach, which is based on averaging the long scale equation and approximating the fast scale impact by localized periodic-in-time problems. Numerical test cases in prototypical 3d configurations demonstrate the power of the approach.