At present, several different competing mechanical configurations are used in chemical mechanical polishing. These range from classical rotary designs to orbital and linear systems, as well as the more recent web format. Invariably, wafer rotation is used in all of these systems to average out gross material removal rates and improve within wafer thickness uniformity. Although this might appear to be trivial and unworthy of serious investigation, in reality the interaction of polishing pad surface structure, along with whatever abrasive particles and chemical agents that might be present is quite complex. In addition, fluid transport between wafer and pad surfaces is strongly affected by pad macrostructure and relative motion of the two surfaces.