Número de Deborah: diferenças entre revisões

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O '''número de Deborah''' é um [[número adimensional]] utilizado em [[reologia]]. Caracteriza a fluidez de um material sob condições específicas de fluxo. O número foi originalmente proposto por [[Markus Reiner]], professor da [[Technion]], inspirado em um versículo bíblico da juíza [[Débora (juíza)|Débora]].
 
== Definição ==
 
O número de Deborah é definido pela razão entre o [[tempo de relaxação das tensões]] e o tempo característico da duração do experimento (ou da simulação computacional). Ela dá a relação do escoamento do material no tempo de observação.
 
:<math alt="De equals tc divided by tp">
\mathrm{De} = \frac{t_\mathrm{c}}{t_\mathrm{p}},</math>
 
onde ''t''<sub>c</sub> é o [[tempo de relaxação]] e ''t''<sub>p</sub> é a escala do tempo de observação.
 
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It is based on the premise that given enough time even the hardest material, like mountains, will flow. Thus the flow characteristics is not an inherent property of the material alone, but a relative property that depends on two fundamentally different characteristic times.
 
Formally, the Deborah number is defined as the ratio of the [[relaxation time]] characterizing the time it takes for a material to adjust to applied stresses or deformations, and the characteristic time scale of an experiment (or a computer simulation) probing the response of the material. It incorporates both on the elasticity and viscosity of the material. The smaller the Deborah number, the material behaves more fluid like with an associated Newtonian viscous flow. At higher Deborah numbers, the material behavior changes to non-Newtonian regime, increasingly dominated by elasticity, reaching solid like behavior with very high Deborah numbers. <ref>{{citation|first=M. |last=Reiner |year=1964|journal=Physics Today|volume =17|issue= 1| page= 62 |title=The Deborah Number|doi=10.1063/1.3051374}}</ref> <ref>[http://rrc.engr.wisc.edu/deborah.html The Deborah Number] </ref>
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where ''t''<sub>c</sub> refers to the [[Stress (mechanics)|stress]] relaxation time (sometimes called the Maxwell [[relaxation time]]), and ''t''<sub>p</sub> refers to the time scale of observation.
 
This incorporates both the elasticity and viscosity of the material. At lower Deborah numbers, the material behaves in a more fluidlike manner, with an associated Newtonian viscous flow. At higher Deborah numbers, the material behavior enters the non-Newtonian regime, increasingly dominated by elasticity and demonstrating solidlike behavior.<ref>{{citation|first=M. |last=Reiner |year=1964|journal=Physics Today|volume =17|issue= 1| page= 62 |title=The Deborah Number|doi=10.1063/1.3051374|bibcode = 1964PhT....17a..62R }}</ref><ref>[http://rrc.engr.wisc.edu/deborah.html The Deborah Number]</ref>
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