When an engineer designs a new car, how can she tell whether her design is efficient? Computer models can provide some information on how air flows around the car. However, airflow is complicated, and our computer models aren't perfect. And it's too expensive to build a full-sized prototype of the car to test. The solution? In the early stages of the design process, engineers use scale models to test airflow and wind resistance.
As Unpredictable as Weather
Air and water patterns are hard to model with computers. The U.S. Military instead creates physical models of ships and airplanes that are tested by scientists using wind and water tunnels. The tunnels allow the scientists to see how air and water flow over the models. These scale models are geometrically similar to the full-sized military vehicles.
Engineers can build models of natural features too. In Louisiana, engineers built a scale model of parts of the Mississippi River. The model shows how sediments flow down the river and how changes to the river affect the areas near its banks. They have used it to test ideas for restoring parts of the Mississippi Basin. Even though computers continue to get more powerful, engineers will depend on scale models for a long time.
See for yourself: http://www.youtube.com/watch?v=9MFWnHkG6YU
Not everything that engineers model becomes a reality. For instance, students from South Dakota recently built a very impractical airplane.
How did the model help the students test their ideas?