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Deborah number



The Deborah number is a dimensionless number, used in rheology to characterize how "fluid" a material is. Even some apparent solids "flow" if they are observed long enough; the origin of the name, coined by Prof. Markus Reiner, is the line "The mountains flowed before the Lord" in a song by prophetess Deborah recorded in the Bible (Judges 5:5).

Formally, the Deborah number is defined as the ratio of a relaxation time, characterizing the intrinsic fluidity of a material, and the characteristic time scale of an experiment (or a computer simulation) probing the response of the material. The smaller the Deborah number, the more fluid the material appears.

The equation is thus:

De = \frac{t_\mathrm{c}}{t_\mathrm{p}}

where tc refers to the relaxation time scale and tp refers to the time scale of observation.

v • d • e
Dimensionless numbers in fluid dynamics
Archimedes • Bagnold • Biot • Bond • Brinkman • Capillary • Damköhler • Dean • Deborah • Eckert • Ekman • Eötvös • Euler • Froude • Galilei • Grashof • Hagen • Knudsen • Laplace • Lewis • Mach • Magnetic Reynolds • Marangoni • Morton • Nusselt • Ohnesorge • Péclet • Prandtl • Rayleigh • Reynolds • Richardson • Roshko • Rossby• Ruark • Schmidt • Sherwood • Stanton • Stokes • Strouhal • Suratman • Taylor • Weber • Weissenberg • Womersley
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Deborah_number". A list of authors is available in Wikipedia.
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