Fluid dynamic gauging: A new tool to study deposition on porous surfaces

The deposition of fouling layers on porous surfaces such as those experienced in membrane/filtration systems has been investigated using the technique of fluid dynamic gauging (FDG). In this work, dead end micro- and macrofiltration processes were simulated using filter paper and glass ballotini suspensions. FDG was used to track, in situ and in real time, the build-up of a ballotini cake during the filtration process. The permeate flux through the filter paper was also simultaneously monitored. Computational fluid dynamics (CFD) studies were performed to illuminate the fluid dynamics of FDG, with particular focus on the flow patterns and on the stresses imposed on the porous surface. The governing Navier-Stokes, Darcy's and continuity equations were solved using the Augmented Lagrangian Method implemented by the commercial partial differential equation solver, Fasflo (TM). The code was first tested successfully against previous studies in the literature featuring fluid flows in crossflow filtration tubular membranes, which had previously been solved by finite difference techniques. Simulations of gauging flow with a permeable gauged surface were then conducted and comparison with filtration experiments showed excellent agreement.