PREDICTIVE MODELING OF LIQUIDS SPREADING ON SOLID-SURFACES

A liquid spreading model is developed in which surface and gravitation al driving energies are balanced against the energy lost through bulk viscous dissipation. Behaviour is described in terms only of independe ntly measurable quantities, with no adjustable parameters. Additionall y, the model can be used to predict liquid viscosity as a function of spreading behaviour. Two different liquid velocity fields are consider ed, one appropriate for bulk droplet spreading, and the other for thin liquid (e.g. small contact angle) spreading. A time constant indicati ng the time scale of bulk limited spreading processes is derived. Appl ication to a lead silicate liquid on a gold substrate demonstrates clo se agreement of the bulk spreading model and predicted time constant w ith experiment; and literature data of the spreading of polydimethylsi loxane liquids on modified Si/SiO2 surfaces demonstrate reasonable agr eement with predictions of the thin liquid model.