Drag reduction in the flow of aqueous solutions of detergent through mesh screens

An experimental study was conducted on the flow of aqueous solutions of detergent through mesh screens to mimic cloth washing. Pressure losses across the mesh screens were measured for water, dilute polymer and several aqueous detergent solutions. A reduction of pressure losses was observed for the flow of aqueous solutions of low molecular weight surfactants such as Laurylether (AE), Laurylbenzene-sulfonic acid-sodiumsalt (LAS), Benzalkonium-chloride (BC) Sodium-dodecyl-sulfate (SDS), and Hexadecyltrimetyl-ammonium-bromide (CTAB), but not for the high molecular weight polymers like Polyethylene-oxide (PEO18) and Polyacrylamide (PAA), through mesh screens. A flow visualization experiment was carried out to observe the flow pattern upstream and downstream of the mesh screen. Photographic images revealed that, instead of an expected large converging flow from the upstream section into the screen opening as in orifice flow, the bulk of the liquid entering the screen aperture took the form of a liquid column of similar diameter as the inlet tube. Based on this observation, a flow model, which led to a new set of definitions of Reynolds number and drag coefficient, was proposed. Good correlations of drag coefficient and Reynolds number were obtained for all test solutions, and the drag reduction phenomenon was manifested for detergent aqueous solutions.