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Drying drop on a substrate: The coffee stain effect

Author: Thomas Breinlinger
Affiliation: Fraunhofer IWM, Fraiburg, Germany

Main category: Engineering (Chemical engineering)
Alternative category: Engineering (Mechanical engineering)

This video shows the drying of a silver ink micro droplet on a solid substrates. The simulation is carried out using the discrete element method (DEM) which is combined with an analytic solution of the fluid motion via one-way-coupling. For visualization of the patterns of solid sediment after drying, only the solid content of the nano-suspension (i.e. the silver particles) is shown. This method can be used e.g. to determine the optimum solid content for a given drop size and a desired sediment pattern (i.e. ring shaped vs fully covered).

Further Reading: T. Breinlinger, T. Kraft, A simple method for simulating the coffee stain effect, Powder Technology, 256:279–284, 2014. (DOI:10.1016/j.powtec.2014.02.024)

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