An extension of Reiner’s “Deborah Number” concept to a Wide field of rheological investigations
Metzner, White and Denn (1) have claimed that, under certain simplifying rheological conditions, “the Reynolds, Weissenberg and Deborah numbers become the sole dimensionless groups which must be considered”. The Reynolds numbers define the relative importance of viscous and inertia forces; the Weissenberg numbers, the ratio of elastic to viscous behaviour; (2) and the Deborah number, (3) the ratio of a relaxation time (τ) to an experimental time (t). Metzner et al. point out that it would have been more in keeping with other work had Reiner used the reciprocal, t/τ but this is not very important.