Particle Image Velocimetry for Ice Modeling

Investigators

Robert Ettema, Marian Muste, Ichiro Fujita (Univ. Gifu, Japan) & Anton Kruger

Research Objective

A new image-based technique, namely Large-Scale Particle Image Velocimetry (LSPIV), was used in a laboratory investigation of ice movement through the confluence of the Mississippi and Missouri Rivers. The goal of the investigation was to determine and map the whole field of ice and water velocities.

Accomplishments

The imaged area covered a surface of 4.1 m by 5.7 m of the hydraulic model. A view of the model ice moving through the model is given in the left figure below. Ice was simulated using 3 mm-diameter beads of polypropylene plastic.

To trace the open-water regions, low concentrations of model ice were released onto the surface water. For the ice-covered regions, in which a more-or-less continuous layer of black beads moved through the confluence, ice vectors were determined using a low concentration mixture of square plates 1 cm x 1 cm x 1 mm of white polypropylene.

The velocity measurements presented here were selected to illustrate the usefulness of the LSPIV technique for mapping the ice velocity. The right figure below shows ice and free surface velocities for the open-water area through the constrained flow path formed by the confluent channels fitted with their actual alluvial bathymetry and ice borders.

LSPIV can produce readily useable velocity data for analysis of various aspects of the flow: instantaneous and mean free surface velocity fields, distribution of velocity at selected cross-sections normal to the banks (the usual data provided by field measurements), temporal variations of velocity at a single location.

Along with the velocity, some other useful information is available. Ice-discharge and its distribution is readily obtainable from the instantaneous or mean velocity fields if the model-ice thickness is measured. Additionally, the temporal and spatial evolution of the ice movement through the river confluence can be qualitatively and quantitatively monitored, which is crucial to illuminate ice jamming mechanism.

Future Plans

It is clear that LSPIV is a powerful and efficient technique for the experimental investigation of the ice-related river hydraulics. Used with aerial photographs, LSPIV holds great promise to aid in the understanding of ice mitigation problems.

Publications

Ettema, R., Fujita, I., Muste, M., Kruger, A. (1997). "Particle-Image Velocimetry for Whole-Field Measurement of Ice Velocities," Cold Regions Science and Technology Journal, 26(2), pp. 97-112.

Ettema, R., Fujita, I., Muste, M., and Kruger, A. (1997), "Particle-Image Velocimetry for Ice-Field Velocities," Proceedings XXVII IAHR Congress, Theme B, Vol.1, San Francisco, CA, pp. 137-142.