Finite element analysis of fluid--solid interaction in the metering nip of a metering size press

摘要

In the metering section of a metering size press, the coat weight and film uniformity are mainly governed by the flow in the metering nip which is delimited by two rotating rolls, one of which (the soft roll) is covered with an elastomer layer. In this region, the shape of the soft layer and the hydrodynamics depend on each other; the soft roll may deform owing to the stresses imparted by the fluid flow which in turn may be altered by this deformation. In this article, a 2D model is proposed for the solution of this fluid--solid interaction problem in the case of the reverse roll coating process. The fluid flow between the two co-rotating rolls is obtained from the solution of the Navier--Stokes equations and the soft roll deformation is predicted from a static analysis under the assumptions that the elastomer is incompressible and Hookean. Both the flow and the elasticity problems are solved using finite element code POLY2D~tm from RheoTek. Finally, the model is tested against experimental data obtained from a laboratory coater.