Buckingham's p theorem
Buckingham's π theorem[′bək·iŋ·əmz ′pī ‚thir·əm]
The theorem that if there are n physical quantities, x1, x2, …, xn, which can be expressed in terms of m fundamental quantities and if there exists one and only one mathematical expression connecting them which remains formally true no matter how the units of the fundamental quantities are changed, namely φ(x1, x2, …, xn) = 0, then the relation φ can be expressed by a relation of the form F (π1, π2, …, π n-m) = 0, where the πs are n-m independent dimensionless products of x1, x2, …, xn. Also known as pi theorem.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.