Deborah number 84397 224240673 2008-07-07T23:16:39Z SmackBot 433328 Date the maintenance tags or general fixes {{Unreferenced|date=July 2008}} 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]] ([[Book of Judges|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: :<math> \mathrm{De} = \frac{t_\mathrm{c}}{t_\mathrm{p}}</math> where ''t''<sub>c</sub> refers to the relaxation time scale and ''t''<sub>p</sub> refers to the time scale of observation. {{NonDimFluMech}} [[Category:Dimensionless numbers]] [[Category:Fluid mechanics]] [[ca:nombre de Deborah]] [[de:Deborah-Zahl]] [[es:Número de Deborah]] [[fr:Nombre de Deborah]] [[ko:데보라 수]] [[it:Numero di Deborah]] [[pl:Liczba Debory]]