Simulating the initial growth of a deposit from colloidal suspensions

Abstract

We study the short time properties of a two-dimensional film growth model in which incident particles execute advective-diffusive motion with a vertical step followed by D horizontal steps. The model represents some features of the deposition of anisotropic colloidal particles of the experiment of Yunker et al (2013 Phys. Rev. Lett. 110 035501), in which wandering particles are attracted to particle-rich regions in the deposit. Height profiles changing from rough to columnar structure are observed as D increases from 0 (ballistic deposition) to 8, with striking similarity to the experimental ones. The effective growth exponents match the experimental estimates and the scaling of those exponents on D shows a remarkable effect of the range of the particle-deposit interaction. The nearly ellipsoidal shape of colloidal particles is represented for the calculation of roughness exponents in conditions that parallel the experimental ones, giving a range of estimates that also includes the experimental values. The effective dynamic exponents calculated from the autocorrelation function are shown to be suitable to decide between a true dynamic scaling or transient behavior, particularly because the latter leads to deviations in an exponent relation. These results are consistent with arguments on short time unstable (columnar) growth of Nicoli et al (2013 Phys. Rev. Lett. 111 209601), indicating that critical quenched KPZ dynamics does not explain that colloidal particle deposition problem.