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An efficient full approximation storage (FAS) Multigrid algorithm is used to solve a range of droplet spreading flows modelled as a coupled set of non‐linear lubrication equations. The algorithm is fully implicit and has embedded within it an adaptive time‐stepping scheme that enables the same to be optimized in a controlled manner subject to a specific error tolerance. The method is first validated against a range of analytical and existing numerical predictions commensurate with droplet spreading and then used to simulate a series of new, three‐dimensional flows consisting of droplet motion on substrates containing topographic and wetting heterogeneities. The latter are of particular interest and reveal how droplets can be made to spread preferentially on substrates owing to an interplay between different topographic and surface wetting characteristics. Copyright © 2004 John Wiley & Sons, Ltd.

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SUMMARY Chemical disorder in silicon suboxides has been modelled by constructing several small atomic clusters which were used as input for multiple scattering calculations of the energy‐loss near‐edge structure at the oxygen K‐edge. A redistribution of intensity at the O K‐edge is observed as the number of second neighbour oxygen atoms is reduced. Since photoelectrons scattered by second neighbours of oxygen (at least) contribute to the spectra, O K‐edge data provide valuable structural information, additional to that obtained from the Si L23‐edge, which appears to be restricted to the local coordination shell. Comparison with the experimental O K‐edge for a‐SiOx (O < × < 2), prepared by oxidation of amorphous Si, suggests that the material consists of an intimate mixture of a wide range of Si sites with varying proportions of oxygen and silicon in the first neighbour shell.

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