12,000

We have over 12,000 students, from over 100 countries, within one of the safest campuses in the UK

93%

93% of Lancaster students go into work or further study within six months of graduating

Home > Research > Publications & Outputs > A model for the settling of nonuniform cohesive...
View graph of relations

« Back

A model for the settling of nonuniform cohesive sediment in a laboratory flume and an estuarine field setting

Research output: Contribution to journalJournal article

Published

Journal publication date1993
JournalJournal of coastal research
Journal number4
Volume9
Number of pages12
Pages1094-1105
Original languageEnglish

Abstract

A numerical model for deposition of non-uniform cohesive sediment at a point was applied to laboratory and field settings. The results were compared with those from a uniform sediment model applied to the same settings. In the non-uniform (distributed) model, classes of sediment (representing different floc sizes) each had a corresponding settling velocity and critical shear stress for deposition. The models were applied to laboratory deposition tests in an annular flume. Tests with steady and slowly decelerating flow were both modelled. The distributed sediment model was shown to be a much better model of deposition in decelerating flow in the closed system of the annular flume. The model was shown to be sensitive to the settling velocity of the class corresponding to the largest flocs. The importance of more accurate methods of determining floc size and settling velocity distributions was recognised. Both models were also applied to field measurements of deposition during a tide made in the Mersey Estuary. Both models gave a reasonable fit to the data, but the distributed sediment model did not significantly improve the uniform sediment model for field use. External influences and advection of sediment from outside the immediate area were shown to affect the field measurements.