Flows in Rotation Cylinder Filled With Polymer Solutions

2006 ◽  
Author(s):  
Jae Won Kim ◽  
JaeMin Hyun ◽  
Eun Young Ahn
Keyword(s):  
Apparent Viscosity ◽  
Polymer Solutions ◽  
Side Wall ◽  
Velocity Shear ◽  
Working Fluid ◽  
Shear Rates ◽  
Ctab Solution ◽  
Applied Shear Stress ◽  
Shear Front ◽  
Solid Walls

This investigation deals with the spin-up flows in a circular container of aspect ratio, 2.0. Shear front is generated in the transient spin-up process of the present flow system and it is propagating from the side wall to the central axis in a rotating container. Propagation of the shear front to the axis in a rotating container means the region behind the shear front acquires an angular momentum transfer from the solid walls. Propagating speed of the shear front depends on the apparent viscosity of polymer solution. Two kinds of polymer solutions are considered as a working fluid: one is CMC and the other is CTAB solution. CMC solution has larger apparent viscosity than that of water at the present applied shear stress, and CTAB shows varying apparent viscosities depending on the applied shear rates. Transient and spatial variations of the apparent viscosities of the present polymer solutions (CTAB and CMC) cause different propagating speeds of the shear front. In practice, CMC solution that has larger values of apparent viscosity than that of water always shows rapid approach to the steady state in comparison of the behavior of the flows with water. However, for the CTAB solution, the propagating speed of the shear front changes with the local magnitude of its apparent viscosity. Consequently, the prediction of Wedemeyer’s including viscosity in the propagating speed of the velocity shear front quantitatively agrees with the present experimental results.

Propagation of the Velocity Shear Front in Spin-up From Rest in a Cut-Cone

1995 ◽  
Vol 117 (1) ◽  
pp. 58-61 ◽  
Author(s):  
Jae Won Kim ◽  
Jae Min Hyun
Keyword(s):  
Side Wall ◽  
Azimuthal Velocity ◽  
Processing Technique ◽  
Velocity Shear ◽  
Image Processing Technique ◽  
Incline Angle ◽  
Homogeneous Fluid ◽  
Experimental Apparatus ◽  
Ekman Layers ◽  
Shear Front

The behavior of the dominant azimuthal velocity field during spin-up from rest of a homogeneous fluid in a cut-cone is investigated. The fundamental mechanism of spin-up process is recapitulated. In line with the classical flow model of Wedemeyer, the importance of the meridional circulation, driven by the Ekman layers, is stressed. The experimental apparatus, together with the image processing technique of the visualized flow data, is described. The reliability and accuracy of this experimental method are validated by performing parallel measurements using an LDV system. The experimental results clearly indicate that the azimuthal velocity shear front propagates faster as the incline angle of the side wall decreases. In the rotating zone of the interior, the azimuthal velocities are larger in magnitude in a cut-cone than in a circular cylinder of comparable size. Plausible physical explanations are offered, and the experimental observations are supportive of these physical arguments.

scholarly journals Rheological Properties of Wood–Plastic Composites by 3D Numerical Simulations: Different Components

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 417
Author(s):  
Xingcong Lv ◽  
Xiaolong Hao ◽  
Rongxian Ou ◽  
Tao Liu ◽  
Chuigen Guo ◽  
...  
Keyword(s):  
Flow Field ◽  
Rheological Properties ◽  
Wood Fiber ◽  
Velocity Shear ◽  
Wood Plastic Composites ◽  
Shear Rates ◽  
Plastic Composites ◽  
Power Law Fluids ◽  
Field Information ◽  
Computational Fluid Dynamics Cfd

The rheological properties of wood–plastic composites (WPCs) with different wood fiber contents were investigated using a rotational rheometer under low shear rates. The flow field information was analyzed and simulated by Ansys Polyflow software. The results showed that the WPCs with different wood fiber contents behaved as typical power-law fluids. A higher wood fiber content increased the shear thinning ability and pseudoplasticity of the WPCs. The pressure, velocity, shear rate, and viscosity distributions of the WPC during extrusion could be predicted by computational fluid dynamics (CFD) Ansys Polyflow software to explore the effects of different components on the flow field of WPCs.

Effects of Flow Properties of Lithium Soap Greases on Bearing Torque

2019 ◽  
Vol 823 ◽  
pp. 123-127
Author(s):  
Norifumi Miyanaga ◽  
Mitsumi Nihei ◽  
Jun Tomioka
Keyword(s):  
Apparent Viscosity ◽  
Small Amplitude ◽  
Shear Stresses ◽  
Flow Properties ◽  
Small Amplitude Oscillatory Shear ◽  
Small Ball ◽  
Shear Rates ◽  
Lithium Soap ◽  
Viscoelastic Behaviors ◽  
Plate Type

This study describes the influence of flow properties of lithium soap greases on torque of small ball bearings. Three types of greases with different worked penetration were tested in this study. Their rheological properties are revealed by a cone plate type rheometer. Shear stresses under various shear rates are fitted with the Herschel-Bulkley equation. In addition, viscoelastic behaviors of the greases are measured by small amplitude oscillatory shear. The crossover stress that means the shear stress at G’=G” is obtained for the greases. Then, the bearing torque when three types of greases are used as a lubricant is measured. As the results, the grease with higher crossover stress shows the lower bearing torque regardless of that it has larger apparent viscosity. On the other hand, the grease with lower crossover stress shows the higher bearing torque regardless of that it has lower apparent viscosity. These results imply that the channeling state appears in the grease with higher crossover stress while the churning state appears in the grease with lower crossover stress.

Bathymetrically controlled velocity-shear front at a tidal river confluence

2015 ◽  
Vol 120 (8) ◽  
pp. 5850-5869 ◽  
Author(s):  
Cheryl Ann Blain ◽  
Richard P. Mied ◽  
Paul McKay ◽  
Wei Chen ◽  
W. Joseph Rhea
Keyword(s):  
Tidal River ◽  
Velocity Shear ◽  
River Confluence ◽  
Shear Front

Rheology of Brine-Based Fuzzy-Ball Drilling Fluids in Deepwater Drilling

2019 ◽  
Author(s):  
Zhaochuan Li ◽  
Lihui Zheng ◽  
Panfeng Wei ◽  
Xiaojuan Dai ◽  
Weian Huang
Keyword(s):  
Low Temperature ◽  
Yield Point ◽  
Apparent Viscosity ◽  
High Salinity ◽  
Flow Behavior ◽  
Plastic Viscosity ◽  
Rheological Parameters ◽  
Working Fluid ◽  
Drilling Fluids ◽  
Deepwater Drilling

Abstract In deepwater drilling, the rheology of traditional drilling fluid is uncontrollable since the fluid usually mixes with brine and encounters low temperature. A solution may be to use the newly designed brine-based fuzzy-ball drilling fluids (BFDFs) since these have a well-adapted rheology under high salinity and low temperature condition. This has the potential to make drilling safer and more efficient. In this experiment, the rheological properties of BFDFs under test conditions were characterized with a rheometer by varying salinity (2 to 20 mass%) and temperature (4 to 80 °C). The rheological parameters considered are apparent viscosity (AV), plastic viscosity (PV), yield point (YP), and θ6 reading. To characterize the magnitudes of changes of the rheological parameters and their low temperature dependence, their ratios at 4 and 25 °C, and 4 and 80 °C were calculated. The results showed that the apparent viscosity (AV), the plastic viscosity (PV), the yield point (YP), and θ6 reading of BFDFs increased slightly with the decrease of salinity and temperature. The ratios of rheological parameters at 4 and 25 °C were close to unity, while the ratios at 4 and 80 °C were about two. The flow behavior of BFDFs under high salinity and low temperature condition was stable. Therefore, brine could be used as the base fluid for BFDFs. Theoretically, the flow behavior of BFDFs under low temperature condition seems to follow the Herschel-Bulkley model. Practically, the tests indicated that the BFDFs possess a strong tolerance to sandstone cuttings and Cabentonite, an excellent inhibitive property to shaly cuttings, weak corrosive characteristics against N80 casing steel, excellent lubricity properties, and remarkable biodegradability. In summary, the empirical results showed that the newly designed fuzzy-ball working fluid can use brine instead of fresh water as based fluid and maintain remarkable properties under high salinity and low temperature condition. Properties of BFDFs could basically satisfy the requirement of deepwater drilling work.

Rheological Behavior of Agar Solution in Relation to the Making of Instant Edible Bird's Nest products

2012 ◽  
Vol 8 (3) ◽  
Author(s):  
Lu Zhang ◽  
Liming Che ◽  
Weibiao Zhou ◽  
Xiao Dong Chen
Keyword(s):  
Apparent Viscosity ◽  
Arrhenius Equation ◽  
Fluid Model ◽  
Empirical Correlations ◽  
Shear Rates ◽  
Agar Solution ◽  
Liquid Material ◽  
Different Temperatures ◽  
Edible Bird’S Nest ◽  
Rotary Viscometer

Abstract Agar solution has been used in industry as a “background” liquid material for the production of instant Edible Bird’s Nest products. In this work, the rheological properties of agar solution were studied, especially the effect of shear rate, agar concentration and temperature, respectively, on the apparent viscosity of the agar solution. A HAAKE rotary viscometer was used. Results indicated that the agar solution exhibited shear-thinning behavior following the power law fluid model. Its apparent viscosity increased exponentially with an increase of solid concentration, and decreased with a rise of temperature. The independence of viscosity on temperature followed Arrhenius equation. Reasonable empirical correlations between the apparent viscosity of the agar solution for different temperatures, shear rates and different concentrations are proposed respectively.

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