Particle deposition in low-speed,high-turbulence flows

The experimental and numerical study considers the concentration of airborne particulate contaminants, such as spores of spoilage fungi, and their deposition on a surface, in a Petri dish, and on a warm box-shaped product placed in a food-processing environment. Field measurements by standard, active and passive samplers provide typical values of airborne concentrations and specific deposition fluxes. Velocity and turbulence data from field studies are used as input in large eddy simulations of the process, and estimates of deposition fluxes are of the same order of magnitude as those deduced from field measurements. Particle deposition is shown to be associated with near-wall coherent structures. Flow reversal, simulated by impulsive start, is shown to give higher deposition rates than steady mean flows.