Information about the Lateral Profile Applet

Autor: A. Malcherek

General Description

The Lateral Profile Applet (LPA) calculates the lateral velocity profile in a river using the formula

with:

u	the main stream velocity
y	a co-ordinate perpendicula to the main stream
C	the Chezy coefficient
h	the depth of water
nu	the lateral viscosity according to Elder
d z_S / d x	the free surface gradient (assumed to be positiv)

This formula is valid, if and only if

• the bottom friction can be described by Chezy's formula (which as a matter of fact is not the best one to describe the bottom friction)

(otherwise use the Bed Roughness Parameter Calculator)

• the effects of lateral turbulent viscosity can be calculated according to Elder's law.

• the flow is stationary in time

• the river is stright i.e. has no curves

• the bottom contours do not change along the river

• which means that the river width is constant

• and of course there is no wind stressing the free surface.

How to use the Applet

1. The user must define the free surface gradient.
2. The user has two possibilities to fill out the table, which is more easy than it seems to, because the table does not need a special format.

   Every line stands for a profile position which follows the lateral co-ordinate y. The user defines the profile position, the measured water depth and: the Chezy coefficient OR the velocity depending on the calculation modus.

   Beginners should use the predefined profiles which are prepared in a drop-down list at the LPA's bottom.

3. Press the Calculate button. The table will be filled out with the missing quantity.
4. Press the Diagram button and the profiles of the velocity, the Chezy and the water depth will become visible.

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