Geometric SimilarityGeometric SimilarityWhen we equate Pi terms involving length ratios only, the model satisfies the condition of geometric similarity. Scale models in which all three dimensions of the model (height, width, and length) have the same scale have geometric similarity. A common dimensionless Pi term involving geometry is the ratio of length to width or the ratio of two lengths.
Lee Waite, Ph.D., P.E.; Jerry Fine, Ph.D.: Applied Biofluid Mechanics, Second Edition. Geometric Similarity, Chapter (McGraw-Hill Professional, 2017), AccessEngineering