IAHR Document Library

« Back to Library Homepage « Proceedings of the 35th IAHR World Congress (Chengdu, 2013)

Scale Effects in Modelling Two-Phase Air-Water Flows

Author(s): Michael Pfister; Hubert Chanson

Linked Author(s): Hubert Chanson, Michael Pfister

Keywords: Ir; Hydraulic structures; Physical modeling; Scale effects; Two-phase flow; Water

Abstract: Beside analytical approaches, physical modelling represents probably the oldest design tool in hydraulic engineering. For free surface flows, the similitude according to a Froude similarity allows for a correct representation of the dominant forces, namely gravity and inertia. In parallel, fluid constants such as the surface tension and the viscosity might be incorrectly reproduced, affecting the air entrainment and transport capacity of a high-speed model flow. Consequently, small physical models operated under the Froude similitude systematically underestimate the air entrainment rate and air-water interfacial properties. To limit this deficit, minimal values of the Reynolds or Weber number have to be respected. The paper summarises the physical background of these limitations and their combination in terms of the Morton number. Based upon a literature review, these limits are listed and discussed, resulting in a series of more conservative recommendations in terms of air concentration scaling.


Year: 2013

Copyright © 2024 International Association for Hydro-Environment Engineering and Research. All rights reserved. | Terms and Conditions