This

**preview**shows pages 1-3. to view the full**28 pages of the document.**Objective:

describe how and when particles get entrained by flows in water

(sediment transport), or are deposited (non cohesive)

Why is this important?

We want to be able to understand what types of flows carry what

types of sediment to:

1) Predict sediment transport

2) And to determine what flows might have transported grains we

find in ancient sediment deposits.

You need to learn:

Reynolds number meaning and equation

Froude number meaning and equation

Stokes Law meaning and equation

Quadratic stress law for shear stress and shear velocity

Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

What do we need to know?

Fluid:

density

viscosity

velocity distribution

From this, calculate BED shear stress

Particles:

Diameter

Shape

Density

From this, calculate CRITICAL shear

stress

Is BED shear stress greater than

CRITICAL shear stress?

Other factors:

gravity

bed configuration

Is the sediment cohesive?

Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

Properties of the flow

f fluid density, M L-3 (Greek letter

rho)

μ molecular viscosity (also called

dynamic viscosity, because it is

only apparent in a moving

fluid), force per unit area per

velocity gradient, ML-1 T-1, Ns

m-2 (Greek letter mu)

~0.001 Ns/m2 at 20°C, or 0.01

Poises (cgs)

v kinematic viscosity (/f)

(Greek letter nu)

Vertical axis=

μ x 1000 Ns/m2

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