Microstructure Simulation of Early Paper Forming Using Immersed Boundary Methods

Paper in proceeding, 2011

Paper forming is the first step in the paper machine where a fiber suspension leaves the headbox and flows through a forming fabric. Understanding this process is important for the development of improved paper products because the configuration of the fibers during this step has a large influence on the final paper quality. The simulation framework includes IBOFlow, a stateof- the-art Navier-Stokes solver, and PaperGeo, the virtual paper structure generator in GeoDict. Immersed Boundary Methods are used to resolve the flow around the fibers. The fibers are modeled with a finite element discretization of the Euler-Bernoulli beam equation in a co-rotational formulation. The contact model is based on a penalty method and includes friction as well as elastic and inelastic collisions. The fiber model and the contact model are validated against demanding test problems from the literature with excellent result. The fluid-structure interaction in the model is examined by simulating an elastic beam oscillating in a cross flow. Finally, a simulation of initial paper forming is performed, which demonstrates the capabilities of the simulation framework.