Über die Grenzen des stationären Flüssigkeitstransportes in offenen Kapillarkanälen (English shop)

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Uwe Rosendahl’s book on the limits of steady liquid transport in open capillary channels deals with forced liquid flows in uniform channels under compensated gravity. The focus of interest lies on the causes that limit steady liquid transport and thereby lead to instability of the flow. The flow problem is investigated both theoretically and experimentally using a channel formed by parallel plates.

The theoretical description of the flow is provided by a one-dimensional mathematical model that includes the complete modelling of the irreversible pressure loss and of the liquid surfaces. The model equations are solved numerically and yield the fundamental flow quantities by means of which the flow can be classified. The behaviour of the capillary flow reveals fundamental similarities to flows in compressible gases or to open channel flows. In particular, the author is able to demonstrate that, under certain conditions, the limits of liquid transport are caused by a choking effect such as is known from gas dynamics.

The verification of the theoretical model is based on experimental results obtained by the author at the Bremen drop tower and by means of a sounding rocket (TEXUS). They cover a comparatively wide range of the relevant characteristic numbers and provide insight into the different manifestations and the behaviour of the flow. In particular, they confirm the choking effect as the cause of the occurrence of the flow instability.

The book is a contribution to basic research in the field of capillary-dominated flows and, through its novel findings, contributes substantially to the general understanding of open capillary flows.