272-304. This situation is perhaps partly explainable given that in a wide range of … The ratio t f /t r is a dimensionless number of particular significance in the study of flow of non-Newtonian fluids: depending on the circumstances, this number is called the Deborah number or the Weissenberg Number. J. Fluid Mech., 677 (2011), pp. The Weissenberg number indicates the degree of anisotropy or orientation generated by the deformation, and is appropriate to describe flows with a constant stretch history, such as simple shear. It quantifies the observation that given enough time even a solid-like material might flow, or a fluid-like material can act solid when it is deformed rapidly enough. Despite their different origins, and the fact that they quantify different effects, they are frequently used as synonyms. Table 2. Dimensionless numbers in fluid mechanics are a set of dimensionless quantities that have an important role in analyzing the behavior of fluids.Common examples include the Reynolds or the Mach numbers, which describe as ratios the relative magnitude of fluid and physical system characteristics, such as density, viscosity, speed of sound, flow speed, etc. On the other hand, if the time of relaxation of the ma-terial is larger than your … The deformation rate however, does appear directly in the Weissenberg number, … (1965), there are important differences in more complex flows that are associated with the unsteadiness (in either the Eulerian or Lagrangian sense) of the process, and these two dimensionless measures of viscoelastic effects are typically … I'm that guy. The Weissenberg number indicates the degree of anisotropy or orientation generated by the deformation, and is appropriate to describe flows with a constant stretch history, such as simple shear. Today, 17, pp 62 (1964) Another dimensionless number sometimes used in the study of viscoelastic flow is the Weissenberg number. Planar contraction flows of non-Newtonian fluids with integral constitutive models are studied to investigate the problem of numerical breakdown at high Weissenberg or Debrorah numbers. While Wi is similar to the Deborah number and is often confused with it in technical literature, they have different physical interpretations. is similar to the Weissenberg number and is often confused with it in technical literature, they have different physical interpretations. Grid Control volumes Δ x m i n ∕ R 2; mesh 1: 1800: 0.096: mesh 2: 5560: 0.048: mesh 3: 21 500: … Englisch-Deutsch-Übersetzungen für Weissenberg number Ws im Online-Wörterbuch dict.cc (Deutschwörterbuch). Mesh parameters. Computational rheology started in the early 1970s. Moreover, a non-monotonic relation between shear stress and … Als „Beobachtungszeit“ kann z. Divergent flow in contractions . The Deborah number D e is defined as the ratio of characteristic time of the fluid to the time scale of the process. Mit dem erfolgreichen Abschluss zahlreicher Projekte seit der Gründung im Jahr 2012 zählt WEISSENBERG mittlerweile zu den Top IT-Beratungshäusern und hält an seinen Standorten bei zahlreichen Kunden den Status als strategischer Partner. in a steady channel flow the Deborah number and the Weissenberg number are interchangeable. The difference in material behaviour is characterized by the level and nature of elasticity present in the material when it deforms, which takes the material behaviour to the … Fine points that I've never caught in the past are that the observation time is not the reciprocal of the deformation rate, and that the Deborah number is identically zero for steady state flows. As the Weissenberg number (Wi) increased, the flow developed from a Newtonian-like to vortex growth, ... Dynamics of high-Deborah-number entry flows: a numerical study. Weissenberg number: | The |Weissenberg number| (|Wi|) is a |dimensionless number| used in the study of |vi... World Heritage Encyclopedia, the aggregation of the largest online encyclopedias available, and the most definitive collection ever assembled. Since their introduction to the literature nearly fifty years ago the Deborah and Weissenberg numbers have proved invaluable for rheologists in quantifying viscoelastic effects. Since their introduction to the literature nearly fifty years ago the Deborah and Weissenberg numbers have proved invaluable for rheologists in quantifying viscoelastic effects. It excludes complicated e ects of shear-dependent viscosity and thus allows one to emphasize the in uence of uid s elasticity on characteristics of its boundary layer. While Wi similar to the Deborah number, and is often confused with it in technical literature, they have different physical interpretations. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE. In contrast, the Deborah number should be … The Weissenberg number indicates the degree of anisotropy or orientation generated by the deformation, and is appropriate to describe flows with a constant stretch history, such as simple shear. The high-Weissenberg number problem A 30 year old mystery. Find out more about the company LUMITOS and our team. For instance, in simple steady shear, the Weissenberg number, often abbreviated as Wi or We, is defined as the shear rate times the relaxation time (). Deborah number - Wikipedia The Weissenberg effect was named after him, as was the Weissenberg number. Alves, R.J. Poole. It is named after Karl Weissenberg.The dimensionless number is the ratio of the relaxation time of the fluid and a specific process time. The Weissenberg number is a dimensionless number used in the study of viscoelastic flows. Die Relaxationszeit wäre im einfachsten Fall jene aus einem Maxwell-Modell des Fluids. In steady flow, as considered in this study, it is equal to the Weissenberg number and both are used equivalently here. … So far, the exact solution corresponding to the unsteady ow of a Maxwell uid … It was my first job righ... One of the big corn processors from here in the Midwest is suggesting that isosorbide could be used as a replacement for bisphenol A (BPA) ... A plastic wheel rim, made from BASF's Ultramid (nylon) with long glass fiber reinforcement: While the engineers in the video make some ... (c) Copyright 2006 - 2015, John A. Spevacek, Free Access to Research in the Polymer Literature, Fundamentals of Dynamic Mechanical Analysis, Significant Acceleration of a UV-Cured Coating (Part 1 of 2), Significant Acceleration of a UV-Cured Coating (Part 2 of 2), Nanoemulsions for Dissolving Polymer Films, The Wall Street Journal and "Glass Transition", 10 Things I Wish I Would Have Learned In School, A New Option for Accessing Research - Renting. Engineers have always loved dimensionless numbers [*], groups of variables where the units cancel leaving them free from the chosen system of measurement. dict.cc English-German Dictionary: Translation for Weissenberg number Deborah Number. The Weissenberg number Ws is named after Karl Weissenberg, an early worker in the field of non-Newtonian fluids. Dynamics of high-Deborah-number entry flows: a numerical study - Volume 677 - A. M. AFONSO, P. J. OLIVEIRA, F. T. PINHO, M. A. ALVES . The Weissenberg number indicates the degree of anisotropy or orientation generated by the deformation, and is appropriate to describe flows with a constant stretch history, such as simple shear. The Weissenberg number indicates the degree of anisotropy or orientation generated by the deformation, and is appropriate to describe flows with a constant stretch history, such as simple shear. The guy that everyone hates. Hi,Thanks for the write up.I cannot get this publication from th e link- http://www.rheology.org/sor/publications/rheology_b/RB2010Jul-a.pdfwould be great if you could help me to get it? The Weissenberg number indicates the degree of anisotropy or orientation generated by the deformation, and is appropriate to describe flows with a constant stretch history, such as simple shear. To use all functions of this page, please activate cookies in your browser. Die Weissenberg-Zahl {\displaystyle {\mathit {Wi}}}, benannt nach dem Physiker und Rheologen Karl Weissenberg, ist eine dimensionslose Kennzahl zur Beschreibung des viskoelastischen Stoffverhaltens von Fluiden. time for the deformation process is infinite and the Deborah number is therefore zero for such flows regardless of the relaxation time of the material. Tapan,The link has been fixed. © 1997-2021 LUMITOS AG, All rights reserved, https://www.chemeurope.com/en/encyclopedia/Weissenberg_number.html, Your browser is not current. Read what you need to know about our industry portal chemeurope.com. the fundamental number of rheology, bringing solids and fluids under a com-mon concept, and leaving Heraclitus'-n-avra pei as a special case for infinite time of observation or infinitely small time of relaxation. We demonstrate the stability of the method in the experimentally relevant range of high Weissenberg numbers. Please note, due to essential maintenance online transactions will not be possible between 09:00 and 13:00 BST, on Monday 20th January 2020 (04:00-08:00 EDT). Mostly finite-element … As for the numbers, the Deborah number is ratio of the relaxation time of the polymer divided by the observation time. CrossRef View Record in Scopus Google Scholar. Toward a solution to the high Weissenberg number problem David Trebotich∗1 1 Center for Applied Scientific Computing, Lawrence Livermore National Laboratory, P.O. 1, S. 62: The Deborah Number Literatur John M. Dealy: Weissenberg and Deborah numbers – their Definition and Use , … Furthermore, the division between energy and entropy elasticity is investigated in detail with regard to the … A: Being born a man. The Weissenberg number indicates the degree of anisotropy or orientation generated by the deformation, and is appropriate to describe flows with a constant stretch history, such as simple shear. Dimensionless numbers in fluid mechanics are a set of dimensionless quantities that have an important role in analyzing the behavior of fluids.Common examples include the Reynolds or the Mach numbers, which describe as ratios the relative magnitude of fluid and physical system characteristics, such as density, viscosity, speed of sound, flow speed, etc. If a rheological experiment is faster than the relaxation process, the material will appear elastic (high De number), otherwise the viscous part will dominate (low De number). Spurious shear stress extrema are found on the wall downstream of the re-entrant corner for both sharp and rounded corners. Box 808, L-560, Livermore, CA 94551, USA. number, the Deborah number De (or Weissenberg number) and is defined as the ratio of material to process time. To use all the functions on Chemie.DE please activate JavaScript. "p("u +"uT) It is when We>1 (memory range comparable to characteristic flow time) that life becomes interesting (and complicated). The Weissenberg number indicates the degree of anisotropy or orientation generated by the deformation, and is appropriate to describe flows with a constant stretch history, such as simple shear. Just as the Reynolds number is a convenient measure of the ratio of inertial to viscous forces, so the Weissenberg number can be viewed as a ratio of elastic to viscous effects. Reiner named this dimensionless number after the prophete Deborah who, in the Book of Judges, proclaimedThe mountains flowed before the lord. We present results of a numerical study of high Weissenberg number flowsusing themethod of Trebotich, Colellaand Miller, The Weissenberg number indicates the degree of anisotropy or orientation generated by the deformation, is appropriate to describe flows with a constant stretch history, such as simple shear. Toward a solution to the high Weissenberg number problem David Trebotich∗1 1 Center for Applied Scientific Computing, Lawrence Livermore National Laboratory, P.O. Deborah numbers of up to .. eupper-convectedMaxwell uidisaclassofviscoelas-tic uid that can explain characteristics of uid relaxation time. Measurements in How to abbreviate Weissenberg Number? We present results of a numerical study of high Weissenberg number flowsusing themethod of Trebotich, Colellaand Miller, J. Comput. The definition of Ws depends on that of t f which is given by: (1) where tr() denotes trace and e denotes strain-rate given in terms of velocity u by: (2) For a simple shear flow with shear-rate γ: (3) while for a simple extensional flow with extension rate ε: (4) Thus for flow … B. das Inverse einer … The Weissenberg number 2. The first is called the Weissenberg number W e. (Some writers, because of the prior use of W e for the Weber number (ratio of surface tension forces to inertia) prefer to use W i as the symbol.) Despite their different origins, and the fact that they quantify different effects, they are frequently used as synonyms. I'm assuming that the Society changed their URLs since I always just cut-and-paste any addresses into my posts. M.A. ↑ M. Reiner (1964) Physics Today, Band, 17, Nr. Since their introduction to the literature nearly fifty years ago the Deborah and Weissenberg numbers have proved invaluable for rheologists in quantifying viscoelastic effects. While Wi is similar to the Deborah number and is often confused with it in technical literature, they have different physical interpretations. The difference between solids and flu-ids is then defined by the magnitude of D. If your time of observation is very large, or, conversely, if the time of relaxation of the material under observation is very small, you see the material flowing. M Reiner, The Deborah Number, Phys. Thus the Deborah number alone is insufficient to fully characterise effects due to viscoelasticity. Debi Weissenberg currently lives in Cumming, GA; in the past Debi has also lived in Roswell GA and Alpharetta GA. Other names that Debi uses includes Debi L Hill, Deborah Leigh Weissenberg, Deborah Leigh Hill, Deborah L Weissenberg and Debi L Weissenberg. The most popular abbreviation for Weissenberg Number is: Wi The greater the Deborah number, the more solid the material; the smaller the Deborah number, the more fluid it is. Box 808, L-560, Livermore, CA 94551, USA. While Wi similar to the Deborah number, and is often confused with it in technical literature, they have different physical interpretations. In contrast, the Deborah number should be … Deborah number Last updated December 09, 2020. The Deborah number (De) is a dimensionless number, often used in rheology to characterize the fluidity of materials under specific flow conditions. The dimensionless number is the ratio of the relaxation time of the fluid and a specific process time. The Weissenberg number indicates the degree of anisotropy or orientation generated by the deformation, and is appropriate to describe flows with a constant stretch history, such as simple shear. In contrast, the Deborah number should be used to describe flows with a non-constant stretch history, and physically represents the rate at which elastic energy is stored or released. In some aspects, the problem of high Weissenberg number … In contrast, the Deborah number should be used to describe flows with a non-constant stretch history, and physically represents the rate at which elastic energy is stored or released. Die Deborah-Zahl (Formelzeichen: ) ist eine dimensionslose Kennzahl der Rheologie.Sie beschreibt die Zeitabhängigkeit des viskoelastischen Verhaltens eines Fluids als Verhältnis seiner Relaxationszeit zur Beobachtungszeit : =. J. Non-Newtonian Fluid Mech., 144 (2–3) (2007), pp. On occasions, the characteristic time of observation in the definition of the Deborah number has been taken as L/U, so that D e = λU/L; in these circumstances, the Weissenberg number and Deborah number have essentially the same definition and are used interchangeably, even … It is named after Karl Weissenberg. Aufgrund ihrer Ähnlichkeit mit der Deborah-Zahl wird die Weissenberg-Zahl häufig in Verbindung mit ihr verwendet. Summary: Debi Weissenberg is 57 years old and was born on 01/11/1963. The relaxation time (Weissenberg number, We) When We is small (additional) Newtonian viscosity!p! Deborah number - Wikipedia The Weissenberg effect was named after him, as was the Weissenberg number. Therefore the exact definition of all non dimensional numbers should be given as well as the number itself. The Weissenberg number is a dimensionless number used in the study of viscoelastic flows. 2 (1993) “ I think, for the rest of my life, I shall refrain from looking up things. Categories: Fluid mechanics | Non-Newtonian fluids. This situation is perhaps partly explainable given that in a wide range of … For instance, in simple steady shear, the Weissenberg number, often abbreviated as Wi or We, is defined as the shear rate times the relaxation time For instance, citing an analogy between a viscoelastic medium and an electrically conducting fluid containing a magnetic field, Ogilvie and Proctor showed that the dynamics of the Oldroyd-B fluid in the limit of large Deborah number correspond to that of a magnetohydrodynamic (MHD) fluid in the limit of large magnetic Reynolds number. … In contrast, the Deborah number should be used to describe flows with a non-constant stretch history, physically represents the rate at which elastic energy is stored or released Deborah number D = time of relaxation/time of observation. Since this number is obtained from scaling the evolution of the stress, it contains choices for the shear or elongation rate, and the length-scale. 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