Surface and bulk properties of deposits grown with a bidisperse ballistic deposition model

Abstract

We study roughness scaling of the outer surface and the internal porous structure of deposits generated with the three-dimensional bidisperse ballistic deposition (BBD), in which particles of two sizes are randomly deposited. Systematic extrapolation of roughness and dynamical exponents and the comparison of roughness distributions indicate that the top surface has Kardar-ParisiZhang scaling for any ratio F of the flux between large and small particles. A scaling theory predicts the characteristic time of the crossover from random to correlated growth in BBD and provides relations between the amplitudes of roughness scaling and F in the KPZ regime. The porosity of the deposits monotonically increases with F and scales as F 1/2 for small F , which is also explained by the scaling approach and illustrates the possibility of connecting surface growth rules and bulk properties. The suppression of relaxation mechanisms in BBD enhances the connectivity of the deposits when compared to other ballisticlike models, so that they percolate down to F ≈ 0.05.The fractal dimension of the internal surface of the percolating deposits is D F ≈ 2.9, which is very close to the values in other ballisticlike models and suggests universality among these systems.

Random deposition of particles of different sizes

“…Another method to determine α is by using the rms fluctuation of the squared roughness in the steady state, presented in Refs. [21,22]. This procedure gives an estimate for the roughness exponent, which is much less dependent on the finite-size corrections.…”

“…The deposition of particles with size exactly equal to one lattice spacing of the substrate does not lead to the formation of pores because the deposition follows the rules of the random deposition model. The inclusion of a very small fraction of particles of size 2 is sufficient to generate a porous structure, which percolates over the whole deposit [22].…”

“…There are few studies in the literature considering the formation of voids inside the volume [16,22], and only deposits formed by the deposition of particles with two sizes have been analysed. In this section we present the results for the global porosity, where particles of different sizes are taken into account.…”

On the evolution of the snow surface during snowfall

“…Since we focus on implications and applications of these effects on snow structure we will apply either of them likewise. Obvious limitations of the model can in principle be investigated within extensions of BD/KPZ: the influence of imperfect sticking (e.g., as a consequence of crystal shapes) can be addressed by competitive growth models [Braunstein and Lam, 2005]; non-uniform particle shapes or sizes have been studied by Silveira and Reis [2007]; oblique particle incidence (e.g. as a result of steady, low winds) has been studied by Meakin and Krug [1992].…”

Effects of microstructures on mesoscopic morphological transitions in deposition growth models

“…The field is driven by a huge number of technological applications to electronics, optics, chemistry and biology (Ohring 2001;Lakhtakia & Messier 2005), but also has much fundamental scientific interest, as understanding the basic physics involves taking up intriguing theoretical challenges imposed by non-equilibrium growth processes and interface physics; in particular, surface kinetic roughening of growing films has received much attention as a dynamical system that exhibits non-equilibrium critical behaviour (Barabási & Stanley 1995;Meakin 1997;Ódor 2004;Katzav et al 2006;Silveira & Aarão Reis 2007).…”