Numerical Investigation of Foam Mixing in Gypsum Slurry

Foamed gypsum slurry is an integral part of gypsum wallboard. The present work describes the dynamics of foam injection into gypsum slurry, which is a power-law fluid with the consistency and behavior indexes depending on the local foam content. The work is divided into two parts. In the first part, the injection of a single straight foam jet into gypsum slurry at rest is studied numerically. The effect of the initial foam jet radius and velocity on the flow structure is elucidated at two different values of the Schmidt number. Also, the effect of the water stucco ratio (WSR) on the flow development and the rate of mixing is predicted. In the second part, gypsum slurry-foam mixture formed as a result of foam injection into crossflow is described. In both the cases, they are studied as a non-Newtonian power-law fluid with the consistency and behavior indexes depending on air content. The flow under consideration is a submerged jet of a boundary-layer type, which curves under the action of the fluid brought by crossflow. The numerical solution proposed here allows one to address the main parameters of interest – the depth of penetration and the rate of mixing.