Physically Similar Systems - A History of the Concept

Abstract

The concept of similar systems similarsystem arose in physics and appears to have originated with Newton Newton in the seventeenth century. This chapter provides a critical history of the concept of physically similar systems physically similar system, the twentieth century concept into which it developed. The concept was used in the nineteenth century in various fields of engineering (Froude Froude, Bertrand, Reech Reech ), theoretical physics (van der Waals van der Waals, Onnes Onnes, Lorentz Lorentz, Maxwell Maxwell, Boltzmann Boltzmann ), and theoretical and experimental hydrodynamics (Stokes Stokes, Helmholtz Helmholtz, Reynolds Reynolds, Prandtl Prandtl, Rayleigh Rayleigh ). In 1914, it was articulated in terms of ideas developed in the eighteenth century and used in nineteenth century mathematics and mechanics: equations, functions, and dimensional analysis. The terminology physically similar systems was proposed for this new characterization of similar systems by the physicist Edgar Buckingham Buckingham. Related work by Vaschy Vaschy, Bertrand, and Riabouchinsky Riabouchinsky had appeared by then. The concept is very powerful in studying physical phenomena both theoretically and experimentally. As it is not currently a part of the core curricula of science, technology, engineering, and mathematics (STEMsciencetechnology, engineering, and mathematics (STEM)) disciplines or philosophy of science, it is not as well known as it ought to be.