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Fouling remains a long-standing unsolved problem that hinders the widespread use of membrane applications in industry. This article reports the use of numerical simulations coupled with extensive material synthesis and characterization to fabricate fouling-resistant 3D printed composite membranes. The membranes consist of a thin polyethersulfone selective layer deposited onto a 3D printed flat and double sinusoidal (wavy) support. Fouling and cleaning of the composite membranes were tested by using bovine serum albumin solution in a cross-flow ultrafiltration setup. The transmembrane pressure was regulated at 1 bar and the cross-flow Reynolds number (Re) varied between 400 and 1000. In comparison to the flat membrane, the wavy membrane showed superior performance in terms of pure water permeance (PWP) (10% higher) and permeance recovery ratio (87% vs 53%) after the first filtration cycle at Re = 1000. Prolong testing showed that the wavy membrane could retain approximately 87% of its initial PWP after 10 complete filtration cycles. This impressive fouling-resistant behavior is attributed to the localized fluid turbulence induced by the 3D printed wavy structure. These results show that not only the lifetime of membrane operations could be favorably extended but also the operational costs and environmental damage of membranebased processes could also be significantly reduced.

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Dynamic gauging is a non-contact technique for measuring the thickness of soft deposit layers on solid surfaces immersed in liquid environments, in situ and in real time. The technique works by inducing a flow into a nozzle located close to, and normal to, the deposit surface; the relationship between pressure drop and mass flow rate yields a measure of the distance between the nozzle and the deposit, whence the thickness of the deposit can be deduced. Computational Fluid Dynamics (CFD) studies were performed to illuminate the fluid dynamics of this technique, with particular focus on the flow patterns and on the stresses imposed on the surface. The governing Navier-Stokes equations were solved using the Augmented Lagrangian Method implemented by the commercial partial differential equation solver, Fastflo TM. The code was first tested successfully against previous studies in the literature featuring confined, slow Homann flows, where fluid flowed out of a nozzle. Then, simulations of gauging flows, where fluid enters a nozzle from a confined entry region, were compared with experimental data; good agreement was observed. Laminar Newtonian flows have been investigated, with Reynolds number at the nozzle throat in the range 0 < Ret < 2200. The shear and normal stresses on the gauged surface were predicted using the output from the CFD simulations. An initial comparison of experimental results for power-law fluids (aqueous CMC solutions) demonstrated the versatility of the technique and implied its 2 applicability to more complex fluids, which would be useful for industrial application. The success of this study will enable (i) use of the gauge to measure the strength of deposits, (ii) optimization of the shape of the nozzle for different tasks and (iii) extension of the technique to power-law fluids.