Predicting spray carry over through computational modelling

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Spraying is ubiquitous and finds application within delivery of materials (e.g. paints, agrochemicals, pharmaceuticals, personal-care products) to surfaces (e.g. crops, fabrics, skin). The spraying process is complex and includes physics around (i) a breakup of a (formulated) liquid from a continuous stream on leaving the spray-nozzle into (ii) discrete droplets (the spray) (iii) evaporation of propellant (iv) transport of droplet/particles to surfaces and (v) impact, adhesion or bounce of droplets/particulate into the evolving flow that carries material away from the surface. A modelling approach is proposed which will allow a better understanding of the controlling parameters that describe the fate of droplets/particles sprayed onto surfaces. The proposed approach will focus on personal care products where carryover of particulates into the air can cause respiratory discomfort. A particular feature of this work is that the spray is a complex formulated product and at the point of impact will be a mix of particulates and oils that form the functional coating, with the carrier fluid responsible for the propellant having evaporated from the material. Also, the shape of the surface to which the spray is directed is relatively complex and will also be responsible for how the airflow (and thus the transport) evolves.