Cress Help - sediment transport - properties of sea water and sediment - Z20.1

Properties of sea water and sediment

In this rule some general parameters of water and sediment are calculated:

Viscosity of water

Density of water

Settling of sediment

Shields number

Van Rijns sedimentological diameter and Shields number

The equations are mainly based on the book of Van Rijn and the scour manual. The equations for density of sea water, the viscosity are based on curve-fitting of experimental results, mainly of tests by Delft Hydraulics and Utrecht University.

Input parameters:

S = salinity in ppt

T = temperature in °C

D₅₀ = median grain size [in the input screen of the rule values should be entered in microns, in the equations below S.I.-units are used (thus D₅₀ in m)]

Density of sea water:

Kinematic viscosity

Dynamic viscosity

Relative density

Settling velocity

Sedimentological diameter according to Van Rijn  (see also Schiereck [2001], page 53:

This value is used to calculate the Shields parameter (critical mobility number)

The critical shear velocity is then:

The critical shear stress is then:

References

Van Rijn []

Hoffmans & Verhey [] Scour manual

Schiereck, G.J. [2001] Introduction to bed, bank and shoreline protection, Delft University Press, ISBN 90.407.1683.8