Hydraulics Modeling

A physical model is a scaled representation of a hydraulic flow situation. Both the
boundary conditions (e.g. channel bed, sidewalls), the upstream flow conditions
and the flow field must be scaled in an appropriate manner.
Physical hydraulic models are commonly used during design stages to optimize a
structure and to ensure a safe operation of the structure. They have an important
further role to assist non-engineering people during the `decision-making' process.
A hydraulic model may help the decision-makers to visualize and to picture the
flow field, before selecting a `suitable' design.
In civil engineering applications, a physical hydraulic model is usually a smaller-
size representation of the prototype (i.e. the full-scale structure) (e.g. Fig. 14.2).
Other applications of model studies (e.g. water treatment plant, flotation column)
may require the use of models larger than the prototype. In any case the model is
investigated in a laboratory under controlled conditions.
Hydraulic modeling cannot be disassociated from the basic theory of fluid
mechanics. To be eefficient and useful, experimental investigations require theoretical
guidance which derives primarily from the basic principles (see Chapter 13) and the
theory of similarity (see the next subsection).
In the present section, we will consider the physical modeling of hydraulic flows:
i.e. the use of laboratory models (with controlled flow conditions) to predict the
behavior of prototype flow situations.
In a physical model, the flow conditions are said to be similar to those in the prototype
if the model displays similarity of form (geometric similarity), similarity of motion
(kinematic similarity) and similarity of forces (dynamic similarity)...

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