Theory of Non-dimensionality

The theory of non-dimensionality states that many physical systems behave similarly when key variables are scaled relative to each other, rather than in absolute terms. By converting variables into dimensionless groups (combinations without units), engineers can analyze different systems using the same principles. This allows for simplified experiments and models—like using a small wind tunnel model to predict full-scale performance—because the behavior depends on these ratios, not on specific sizes or units. Essentially, it helps us understand complex phenomena across different situations by focusing on proportional relationships.