Information about the Lateral Profile Applet
Aus BAWiki
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
- The user must define the free surface gradient.
- 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.
- Press the Calculate button. The table will be filled out with the missing quantity.
- Press the Diagram button and the profiles of the velocity, the Chezy and the water depth will become visible.
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