Determination of the slip layer thickness for a wet foam flow

A foam flowing in a duct is often described by a slip at the wall due to a thin liquid film wetting the wall. Here, we measured its thickness by a conductimetric method. At the top of the duct, the measured thickness agreed with the Bretherton theoretical study for a bubble in a capillary tube. That confirmed the validity of this approach previously used for explaining the wall shear stress values.