This article is within the scope of wikiproject physics, a collaborative effort to improve the coverage of physics on wikipedia. In 1947, karl weissenberg published a paper discussing the ability of some fluids to climb a spinning rod. Simulation tests of the constitutive equation of a. Sorry, we are unable to provide the full text but you may find it at the following locations. Low this article has been rated as lowimportance on the. Measurements of the normal stress effect in solutions of. The weissenberg effect is a phenomenon that occurs when a spinning rod is inserted into a solution of elastic liquid. These data agree with the results of investigations of fixed supramolecular structures, for example, with the work of anderson, give information on the dynamics of the behavior of polymer structures from the moment of their appearance, and reflect the actual. Weissenberg effect in the thick white of the hens egg nature.
Weissenberg effect article about weissenberg effect by. Comparison of the weissenberg effect in spherical and cylindrical symmetry yields the constants. Stub this article has been rated as stubclass on the projects quality scale. The numerical results for the secondary flow are compared with results obtained by flow visualisation.
A tentative explanation of the weissenberg effect in latex. Rod climbing the weissenberg effect nonnewtonian fluid. Higherorder theory of the weissenberg effect journal of fluid. Very low polymer concentration is sufficient to obtain this effect, far from the concentrations at which entanglement can occur. In this work, a comparison of the flow around a spinning disk for a newtonian and a nonnewtonian liquids. An environmentally friendly process for the preparation of uhmwpe asspun fibres the result of a nonzero first normal stress difference during mixing of liquid polymer is a formation of a rod climbing known as weissenberg effect, which was observed. We have observed that this effect can appear when the fluid is stirred without a rod. It will be shown that the last two theories are an oversimplification and do not describe the more complicated behavior of slightly vulcanized latex solutions. These metrics are regularly updated to reflect usage leading up to the last few days. However, when a rotating rod is immersed in a concentrated polymer melt or solution, the meniscus climbs the rod. The thing we see today is called the weissenberg effect and this is how it works. Normal stresses and weissenberg effect normal stresses and weissenberg effect kundu, pijush k.
Describes a simple apparatus to demonstrate the weissenberg effect with gelatin. Normal stress measurements on second order liquids using the weissenberg effect. Dec 21, 2019 deborah number and weissenberg effect. This phenomenon occurred when the rotation speed was increased above a. The three different fluids shown in the video, all of which exhibit the weissenberg effect, are. Investigation of the weissenberg effect in suspensions of. Automatic coldcranking simulator cannon instrument. The microscale weissenberg effect for highviscosity solution. The climbing effect of a viscoelastic fluid when stirred by a spinning rod is well documented and known as weissenberg effectwei et al, 2006.
Download hires image download to mspowerpoint cite this. Pdf general weissenberg effect in free surface rheometry part ii. The relaxation time weissenberg number, we when we is small additional newtonian viscosity. You take a spinning rod and put it into a solution of liquid polymer which is usually very viscous. Ucm, jeffreys, whitemetzner, oldroyd, is the best to model the fluid. Rod climbing the weissenberg effect a dilute solution 0. Pdf within the framework of the navierstokes equations, the weissenberg effect of turbulence is investigated. With the advantages of a higher lengthwall thickness ratio and a more stable free surface compared to those of the traditional weissenberg effect twe, the microscale w. Us9157846b1 us731,863 us2012731863a us9157846b1 us 9157846 b1 us9157846 b1 us 9157846b1 us 2012731863 a us2012731863 a us 2012731863a us 9157846 b1 us9157846 b1 us 9157846b1 authority us united states prior art keywords bob viscometer according centered viscometer space prior art date 20121231 legal status the legal status is an assumption and is not. In the experiment a rod is rotated with its end immersed in the fluid outlined above. Reciprocating weissenberg effect for transporting high.
Aug 07, 2014 the thing we see today is called the weissenberg effect and this is how it works. Rheometry of viscoelastic fluids weissenberg effect. And when you do that, you see that the liquid polymer magically climbs the walls of the rod. Motivations for a fem simulation which 3d constitutive equation e. Rotating a rod in a ferrofluid above some critical angular velocity exhibits this phenomenon.
Oct 08, 2008 the climbing effect of a viscoelastic fluid when stirred by a spinning rod is well documented and known as weissenberg effect wei et al, 2006. On the weissenberg effect of turbulence sciencedirect. The climbing effect of a viscoelastic fluid when stirred by a spinning rod is well documented and known as weissenberg effect wei et al, 2006. This effect, described by garner and nissan and by weissenberg, was treated theoretically by oldroyd, reiner, and rivlin. Transportation of highly viscous solutions at the picoliter level with a rapid dynamic response is paramount for micronanofabrication. Simulation tests of the constitutive equation of a nonlinear. By means of the weissenberg effect data on the deformation and cohesion of polymer structures in shear flow may be obtained. On the emergence of weissenberg effect, the gel was stirred manually for one and a half hours. Evidence that it is a numerical phenomenon but inconclusive whether higher resolution delays of promotes breakdown. Amsterdam printed in the netherlands the weissenberg effect in molten polymers j. Normal stresses and weissenberg effect, journal of. Jul 14, 2007 the three different fluids shown in the video, all of which exhibit the weissenberg effect, are. May 02, 2016 in 1947, karl weissenberg published a paper discussing the ability of some fluids to climb a spinning rod. This effect is usually illustrated by a ferrofluid magnetic fluid, as in this demonstration.
Possibility of using the weissenberg effect to investigate. Weissenberg effect and its dependence upon the experimental. Instead of being thrown outward, the solution is drawn towards the rod and rises up around it. Shearing in the flow of the liquid concentrically around the rotating rod causes the component of the stress normal to the circular flow direction to become greater in magnitude compared to the two other mutually perpendicular components.
In this work, a comparison of the flow around a spinning disk for a newtonian and a nonnewtonian. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks. The microscale weissenberg effect for highviscosity. It has been shown that the sign and magnitude, of the weissenberg effect in a viscoelastic liquid depends on the method of observation, namely, through the shape of the free surface or through the height difference of radial tappings. The deborah and weissenberg numbers rob poole school of engineering university of liverpool, united kingdom since their introduction to the literature nearly fifty years ago the deborah and weissenberg numbers have proved invaluable for rheologists in quantifying viscoelastic effects. Demonstrating the weissenberg effect with gelatin journal. Instead of being driven away from a spinning object, it starts climbing. Weissenberg effect in the thick white of the hens egg. Weissenbergs influence on crystallography professor h. The weissenberg effect happens when a fluid behaves in a very counterintuitive way. This paper reports the results of an experimental investigation to determine the climbing constants of viscoelastic liquids in the rotating rod geometry with two layers of viscoelastic liquids and the results of an investigation which describes the effects of eccentricity on the free surface shape of a nonnewtonian liquid in motion between eccentric cylinders. The normal stress effect of a viscoelastic fluid generated in a viscometric flow, i. A method of determining the second order viscometric function of a simple fluid is described. Enriquez, roberto zenit, octavio manero download pdf.
Normal stresses and weissenberg effect, journal of rheology. A hollow bob 20 a with a plurality of circumferentially spaced holes 30 a. Weissenberg, garner and nissan 4, and garner, nissan and wood 5 have described a number of experiments which indicate that, in highpolymer solutions, steadystate. Rodclimbing effect in newtonian fluids semantic scholar. Weissenberg effect in ferrofluids wolfram demonstrations. The hollow bob 20 a is attached to a bob shaft 10 a and is submerged in a test fluid 40 a. Secondary flows associated with the weissenberg effect nature. Pdf the climbing effect of a viscoelastic fluid when stirred by a spinning rod is well documented and known as weissenberg effectwei et al, 2006 find, read and cite all the. The simple explanation is that the elasticity of the polymers creates a tension in the streamlines. First, in the sense of truesdell physics of fluids, 1964 on the natural time of materials. This is a direct consequence of the normal stress that acts like a hoop stress around the rod. If you have a user account, you will need to reset your password the next time you login. General weissenberg effect in free surface rheometry part.
Rheology of solids 20140309 faculty of pharmacy, omer almukhtar university, tobruk, libya. General weissenberg effect in free surface rheometry part ii. The general form of the stress distribution in laminar flow is the same as that observed previously in other viscoelastic materials, the primary phenomenon being an additional normal tension in the direction of flow. These data agree with the results of investigations of fixed supramolecular structures, for example, with the work of anderson, give information on the dynamics of the behavior of polymer structures from the moment of their appearance, and reflect the actual processes. A appendix aweissenberg effect 99 b appendix bsae viscosity classifications from 10c to 35c101 i index 103. How to do the weissenberg effect science experiment. Video a shows a rod, with its end immersed in this fluid, being rotated. We have investigated the appearance of normal stress differences in suspensions of magnetic nanoparticles by observation of the rise of the fluid at a rotating axis. They deter mined the climbing constant for these fluids and further extended the definition of the weissenberg effect to include the deformed free surface on. This effect is due to the normal stresses that the shear induces. In the weissenberg effect, a nonnewtonian fluid tends to climb up the walls of a spinning rod. Pdf rodless weissenberg effect roberto zenit academia.
The exam will be oral and it will be devoted to evaluate the knowledge acquired and the comprehension of the chemical and physicalmechanical properties of polymers. Weissenberg effect article about weissenberg effect by the. Furthermore, we put forth a general weissenberg number of turbulence, which includes the primary weissenberg number of turbulence as a special. The weissenberg effect makes liquid climb like spaghetti. The highweissenberg number problem a 30 year old mystery. This phenomena, commonly referred to as the weissenberg effect, has an elusive. This discrepancies can be rooted to the definition of the. This is a direct consequence of the normal stress that acts like a hoop stress around the rod the effect is named after karl weissenberg. A newtonian liquid was observed to climb up a rotating shaft whose tip was initially just in contact with the liquid surface. Delivery modes besides the theoretical lectures in the classroom, there will be some exercises in the classroom and some experimental lab hours, with small. The flow properties of a series of tetralin solutions of polyisobutylene are examined with the weissenberg rheogoniometer.
In a newtonian fluid, inertia would dominate and the fluid would move to the edges of the. Shearing in the flow of the liquid concentrically around the rotating rod causes the component of the stress normal to the circular flow direction to become greater in magnitude compared to the. The ratio t r t f is a dimensionless number of particular significance in the study of flow of nonnewtonian fluids. The weissenberg effect or rodclimbing experiment in this video clip a dilute 0. How to do the weissenberg effect science experiment science. Such rob climbing behaviour is referred to as the weissenberg effect. This phenomenon is related to the elasticity of the fluid. Within the framework of the navierstokes equations, the weissenberg effect of turbulence is investigated. In order to understand weissenbergs contribution to xray crystallography it is necessary to appreciate the background to the subject when he entered it around 1922. With the advantages of a higher lengthwall thickness ratio and a more stable free surface compared to those of the traditional weissenberg effect twe, the microscale weissenberg effect mwe can continuously and controllably pump highviscosity solutions.
Us9157846b1 bob for testing rheology and overcoming the. An investigation, with the weissenberg rheogoniometer, of. With concentric cylinder geometry the sample will climb up the spindle of the rotating inner cylinder weissenberg effect. We begin with our investigation on the elastic effect of homogeneous turbulent shear flow. This particular fondamenti di scienza dei polimeri pdf start with introduction, brief session till the indexglossary page, look at the table of content for.
Weissenberg, garner and nissan 4, and garner, nissan and wood 5 have described a number of experiments which indicate that, in highpolymer solutions, steadystate laminar flow cannot be. The reason for this breakdown has remained somewhat of a mystery. Vu department of chemical engineering, mcgill university, 3480 university street, montreal, quebec h3a 2a7 canada received july 14,1977 summary. The weissenberg effect in molten polymers sciencedirect.
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