Kinematic SimilarityKinematic SimilarityWhen we equate Pi terms involving velocity or acceleration ratios, we obtain kinematic similarity. Many Pi terms that have a force dimension will also have a velocity or acceleration dimension. For example, the Reynolds number is a common Pi term in fluid mechanics that has both force dimensions and velocity dimensions. The force dimension shows up in both density and viscosity. To achieve kinematic similarity, and to achieve dynamics similarity, the model and the prototype must have Reynolds number similarity. That is, the Reynolds number of the model must equal the Reynolds number of the prototype.
Lee Waite, Ph.D., P.E.; Jerry Fine, Ph.D.: Applied Biofluid Mechanics, Second Edition. Kinematic Similarity, Chapter (McGraw-Hill Professional, 2017), AccessEngineering