Prediction of Flow Distribution for Bingham Fluid in a Slot Die

Abstract

Designs of flow channel in a slot die are often required to achieve the uniform thickness of coated films for nonNewtonian fluids having nonnegligible yield stress. In previous studies we have proposed a designing method for deriving the optimum geometries of flow channel from a flow distribution model for Bingham fluid. However, it is hard to provide the optimum geometries precisely without manufacturing burden. Therefore, it is useful to substitute simplified asymptotic curves for complex optimum geometries in designing flow channel. But in that case the deviation of outflow from uniformity due to such approximations needs to be checked whether it is within an allowable range or not. In this work we propose a method for predicting the outflow deviation in given geometories of flow channel using Bingham fluid. The usefulness of the method is confirmed by an experiment conducted using a corresponding fluid.