The effect of contact-line motion on the deposition of particles from an evaporating sessile droplet

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D’Ambrosio, Hannah-May and Wray, Alexander W. and Wilson, Stephen K. (2026) The effect of contact-line motion on the deposition of particles from an evaporating sessile droplet. Journal of Fluid Mechanics, 1034. A22. ISSN 0022-1120 (https://doi.org/10.1017/jfm.2026.11246)

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Abstract

A mathematical model for the deposition of particles from a thin sessile droplet undergoing diffusion-limited evaporation in four different modes of evaporation, namely the constant contact radius (CR), constant contact angle (CA), stick–slide (SS), and stick–jump (SJ) modes, is formulated and analysed. Explicit expressions are obtained for the flow and concentration of particles within the droplet, as well as the evolutions of the mass of particles in the bulk of the droplet and in a distributed deposit and/or in one or more ring deposits on the substrate. It is shown that the nature of the deposit depends on both the local evaporative flux and the motion of the contact line. In particular, for a droplet undergoing diffusion-limited evaporation, the flow is outwards towards the contact line in both the CR and CA modes, however, the receding contact line in the CA mode results in a qualitatively different deposit from that in the CR mode, specifically a switch from a ring deposit in the CR mode to a near-uniform deposit in the CA mode. This contrasts with the behaviour of a droplet undergoing spatially uniform evaporation in the CA mode, in which the flow is radially inwards resulting in a peak deposit. For a droplet evaporating in the SS or SJ modes, the final deposit is a combination of the deposit types associated with the CR and CA modes. The present model is validated by finding good agreement between the theoretical predictions for the deposit and previous experimental results.

ORCID iDs

D’Ambrosio, Hannah-May, Wray, Alexander W. ORCID logoORCID: https://orcid.org/0000-0002-3219-8272 and Wilson, Stephen K. ORCID logoORCID: https://orcid.org/0000-0001-7841-9643;
  • Item type:Article
    ID code:96159
    Dates:
    Date
    Event
    10 May 2026
    Published
    30 April 2026
    Published Online
    19 January 2026
    Accepted
    Subjects:Science > Mathematics
    Department:Faculty of Science > Mathematics and Statistics
    Depositing user: Pure Administrator
    Date deposited:30 Apr 2026 11:32
    Last modified:10 May 2026 03:01
    URI:https://strathprints.strath.ac.uk/id/eprint/96159
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