
 HYLE 62 (2000): Modeling in Chemical Engineering 
  The latter are powers of dimensionless numbers, all of which depend on the Reynolds number in complex ways: equations with up to four terms, containing natural logarithms in various places, several occurrences of the Reynolds number, as well as dimensionless numbers characterizing the geometry of the system. 
  A special problem for dimensional analysis are dimensionless magnitudes, in particular shape factors such as the ratio of the length and diameter of a pipe, the relative roughness of a surface, the particle shape factor, or the tortuosity of pores in a packed bed reactor. 
  First, there are a number of background assumptions (models) that apply to all contexts where measurement takes place, in particular a measurement theory (consisting of axioms and operational definitions) for each of the relevant magnitudes, the choice of fundamental units, and the requirement that all equations containing magnitudes have to be dimensionally invariant. 
 www.hyle.org /journal/issues/6/vanbrak.htm (0 words) 
