CFD analysis of blade coating from a reservoir onto a horizontal substrate using a homogeneous two‐phase model

Abstract

AbstractA two‐phase numerical analysis is performed of two‐dimensional, laminar, liquid flow from a reservoir onto a horizontal, rigid, moving substrate. The homogeneous two‐phase model in commercial CFD code CFX is used to model the liquid plus a region containing both liquid and air near the phase interface and downstream of the blade region. Slow convergence due to surface tension modelling required initialization from intermediate results omitting surface tension. Comparisons made with two previous numerical analyses demonstrate the performance of this approach. For a particular upstream reservoir geometry, the effects of changing the substrate speed and the liquid properties from a Newtonian fluid to a Carreau‐Yasuda non‐Newtonian fluid on the pressure field and the downstream film height are studied. The details of the liquid recirculation in the reservoir and the overall pressure distribution are discussed. New results are presented for the meniscus position and contact angle, which are fully predicted by the two‐phase approach. The meniscus position was strongly influenced by substrate speed and liquid properties, whereas the contact angle did not change significantly with changes in substrate speed and dynamic viscosity for the Newtonian fluid nor with changes in the functional parameters for the non‐Newtonian fluid.