Fractal modelling of particulate deposition in the development of black crusts on stone

Publisher Summary The manner in which the structure and porosity of particle agglomerates develop affect the physical properties of materials and also control the growth rate crusts formed on stone. This chapter describes a study conducted to examine the growth and structure of the agglomerates using computer modeling and microscopic examination of developing crusts. Fractal analysis is ideally suited to describe irregular surfaces such as those encountered in particulate deposition and the agglomerates formation. The build up of particulates is studied using a computer model, where a particle migrates towards an agglomeration of particles and sticks at the point of contact. The chapter discusses the preliminary concepts involved in fractal analysis, the models, and the basic results arising from the fractal dimension measurements. The results are discussed with reference to the crusts studied and photographed at St Paul's Cathedral in London.