Interactive Self-Study Module: Modeling and Similitude


This module uses a screencasts to explain the utility of modeling. A physical model that is tested under appropriate experimental conditions can be used to infer the results of a full-scale prototype. Your retention of material in this module will increase if you write down reasons for your answers to ConcepTests, and you try to solve the example problems before watching the solutions in the screencasts.

We suggest using the learning resources in the following order:

  1. Attempt to answer the multiple choice ConcepTest and solve the example problem before watching the screencasts.
  2. Watch the screencast that describes the Pi groups and Buckingham Pi Theorem.
  3. Look over the important equations for modeling and similitude.
  4. Try to solve the example problems before watching the solutions in the screencasts.
  5. Answer the ConcepTests.
  6. Look at the list of key points, but only after you try to list the key points yourself.
  • Rather than using a full-scale prototype to conduct experiments, it is usually easier and less expensive to work with a small model in the laboratory. If the experiment is thoughtfully designed such that similitude is achieved between the model and the prototype, then the experimental results can be used to scale up the results from the laboratory to the full-scale prototype.
  • This module is primarily intended for a Fluid Mechanics course.
Before studying this module, you should:
  • Be able to form and work with dimensionless groups.
  • Recognize common dimensionless numbers, such as the Reynolds number, Froude number, and coefficient of drag.
After studying this module, you should be able to:
  • Determine the experimental conditions necessary to achieve similitude between the model and the prototype.
  • Scale experimental results using a model to a full-scale prototype.