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A systematic study of spiral waves in a realistic reaction-diffusion model describing the isothermal CO oxidation on Pt ( 1 IO) is carried out. Spirals exist under oscillatory, excitable, and bistable (doubly metastable) conditions. In the excitable region, two separate meandering transitions occur, both when the time scales become strongly different and when they become comparable. By the assumption of surface defects of the order of 10 pm, to which the spirals can be pinned, the continuous distribution of wavelengths observed experimentally can be explained. An external periodic perturbation generally causes a meandering motion of a free spiral, while a straight drift results, if the period of the perturbation divided by the rotation period is a natural number.

In the reduction of NO with H, on a Rh(110) surface rectangularly shaped target patterns and spirals with sharp corners have been observed. These patterns can be reproduced with a simple model assuming that the (anisotropic) diffusion is state dependent.Such a dependence is realized in the system Rh(110)/NO + H2 by the presence of different adsorbate-induced reconstructions with varying substrate geometries.

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A bench-top device that can be used to perform fluid dynamic gauging measurements of soft solid layers with zero net liquid discharge and potentially under aseptic (closed system) conditions is demonstrated. Testing results are presented for Newtonian liquids with a range of viscosities: deionised water, 8 wt% and 10 wt% sucrose solutions, 18 wt% glycerol/water solutions and a paraffin oil (1.12-1000 mPa s). The experimental data for discharge coefficient, C d , against clearance/nozzle throat diameter, h/d t , gave good agreement with CFD simulations and the correlation presented by Tuladhar et al. [1]. The influence of surface roughness was studied by making measurements on a series of commercial sandpapers. The rough surfaces gave rise to systematic differences in C d from those obtained with smooth substrates which could not be corrected for using the height of the asperity peaks and careful calibration is therefore required when gauging rough surfaces. Ein Laboranalysemethode zur Messung der Schichtdicke von weichen Feststoffablagerungen mit Hilfe des Fluid Dynamic Gauging wird vorgestellt. Dabei wird im Gegensatz zu bisherigen Anwendungen kein Fluid aus dem System entnommen, was einen aseptischen Betrieb ermöglicht. Erste Ergebnisse werden gezeigt für Newtonische Flüssigkeiten in einem weiten Viskositätsbereich: entionisiertes Wasser, 8 Gew.-% and 10 Gew.-% Zuckerlösung, 18 Gew.-% Glyzerin/Wasser-Lösung und ein Paraffinöl (1,12-1000 mPa s). Die experimentellen Daten für die Abhängigkeit des dimensionslosen Massenstrom C d vom Verhältnis Abstand/Düsendurchmesser h/d t , zeigen eine gute Übereinstimmung mit CFD-Simulationen und der von Tuladhar et al. [1] präsentierten Korrelation.