scholarly journals Discussion: “Dissipative Heating Effects and End Corrections for Viscous Newtonian Flow in High Shear Capillary Tube Viscometry” (Jakobson, J., and Winer, W. O., 1975, ASME J. Lubr. Technol., 97, pp. 472–478)

1975 ◽  
Vol 97 (3) ◽  
pp. 478-478
Author(s):  
R. L. Johnson
Keyword(s):  
Capillary Tube ◽  
Dissipative Heating ◽  
High Shear ◽  
Newtonian Flow ◽  
Heating Effects ◽  
End Corrections

Dissipative Heating Effects and End Corrections for Viscous Newtonian Flow in High Shear Capillary Tube Viscometry

1975 ◽  
Vol 97 (3) ◽  
pp. 472-478 ◽  
Author(s):  
J. Jakobson ◽  
W. O. Winer
Keyword(s):  
Shear Stress ◽  
Apparent Viscosity ◽  
Capillary Tube ◽  
Dissipative Heating ◽  
High Shear ◽  
Flow Curves ◽  
Heating Effects ◽  
Order Of Magnitude ◽  
End Corrections ◽  
Newtonian Behavior

The effect of dissipation heating on the apparent viscosity measured in capillary tube viscometry is described in this paper. Conditions of low Reynolds number and high shear are assumed. End corrections to the tube flow, found to be 3π/16 times the diameter of the tube, are incorporated. The flow curves show decreasing apparent viscosity when the shear stress increases. The configuration of the flow curves plotted in logarithmic presentation are found to be identical for fluids with Newtonian behavior. Convection is the predominant mechanism in removal of the heat in short capillary tube. The estimated upper bound for the shear stress obtainable in short length capillary tubes appears to be of the order of magnitude of 10 MPa limited primarily by the pressure drop associated with the constant end correction from the flat ended inlet and exit of the tube.

High Shear Stress Behavior of Some Representative Lubricants

1975 ◽  
Vol 97 (3) ◽  
pp. 479-485 ◽  
Author(s):  
J. Jakobsen ◽  
W. O. Winer
Keyword(s):  
Shear Stress ◽  
Capillary Tube ◽  
Pressure Level ◽  
High Shear ◽  
Newtonian Viscosity ◽  
Constant Viscosity ◽  
Independent Behavior ◽  
End Corrections ◽  
Silicone Lubricant ◽  
Newtonian Behavior

Shear stress independent behavior was observed for representative, synthetic, nonblended lubricants to about 4.8 × 106 N/m2 (700 psi) shear stress in high pressure viscometric measurements. This shear stress is of the same magnitude as the shear stress in sliding elastohydrodynamic contacts. It is shown that dissipation heating is the only mechanism of importance in the generation of the deviations from constant viscosity as measured with capillary tube viscometric methods. The Newtonian end corrections for the capillary tubes were found to be constant for the nonblended, liquid lubricants. Newtonian behavior will be expected of the fluids in a high shear lubrication situation. Shear induced, nonliquid behavior was found for the silicone lubricant at about 106 N/m2 and for the polymer-blended mineral oil at about 104 N/m2 at a relatively low pressure level. The observations might provide a key to an understanding of the generation of the anomalous low elastohydrodynamic film thickness as found with these lubricants. The polymer-blended oil showed shear thinning effects. The apparent viscosity was found to increase (∼30 percent) with increasing shear stress in the range of the second Newtonian viscosity level.

Effects of Temperature on Rheology of Olive Oils

2009 ◽  
Author(s):  
Nariman Ashrafi
Keyword(s):  
High Shear ◽  
Shear Rates ◽  
Olive Oils ◽  
High Shear Rates ◽  
Heating Effects ◽  
Wide Range ◽  
Minimum Viscosity ◽  
Sensory Changes ◽  
Effects Of Temperature ◽  
Insight Into

In this study, the rheological properties of different samples of olive oils, from the same producer were obtained in a wide range of temperature. At constant temperatures, the shear rate was also varied to obtain heating effects. It was found that all the samples reach a minimum viscosity in the temperature range of 120°C–150°C before thickening to higher viscosities. The viscosity remained almost unchanged in high shear rates regardless of temperature, indicating no shear thinning effects. No thixotropic effects were observed for the olive oils. These findings can provide insight into the microstructural, physiological and sensory changes at frying (high) temperatures.

Pediatric Blood Viscoelasticity Measurements

2007 ◽  
Author(s):  
Neema Nair ◽  
George M. Pantalos ◽  
M. Keith Sharp
Keyword(s):  
Oscillatory Flow ◽  
Capillary Tube ◽  
Cell Aggregation ◽  
High Shear ◽  
Red Cell ◽  
Cardiovascular Devices ◽  
Shear Rates ◽  
High Shear Rates ◽  
Low Shear ◽  
Red Cell Aggregation

Motivated by questions related to flow in pediatric cardiovascular devices, the purpose of this study was to compare pediatric and adult complex viscoelasticity η* = ηV − iηE, where ηV and ηE are viscous and elastic components, respectively, measured in oscillatory flow in a capillary tube [Thurston 1972]. For normal blood, viscosity is increased at low shear rates by red cell aggregation and reduced at high shear rates due to disaggregation, orientation and deformation of red cells. The elastic part is also normally psuedoplastic, indicative of the deformation of red cell aggregates at high shear and individual cells at low shear, respectively.

scholarly journals Oscillatory Carreau flows in straight channels

2020 ◽  
Vol 7 (5) ◽  
pp. 191305
Author(s):  
S. Tabakova ◽  
N. Kutev ◽  
St. Radev
Keyword(s):  
Flow Velocity ◽  
Asymptotic Expansions ◽  
Oscillatory Flow ◽  
High Shear ◽  
Carreau Fluid ◽  
Womersley Number ◽  
Newtonian Flow ◽  
Numerical Examples ◽  
Small Parameters

The present paper studies the oscillatory flow of Carreau fluid in a channel at different Womersley and Carreau numbers. At high and low Womersley numbers, asymptotic expansions in small parameters, connected with the Womersley number, are developed. For the intermediate Womersley numbers, theoretical bounds for the velocity solution and its gradient, depending on the problem parameters, are proven and explicitly given. It is shown that the Carreau number changes the type of the flow velocity to be closer to the Newtonian velocity corresponding to low or high shear or to have a transitional character between both Newtonian velocities. Some numerical examples for the velocity at different Carreau and Womersley numbers are presented for illustration with respect to the similar Newtonian flow velocity.

Non-Newtonian Flow

1952 ◽  
Vol 44 (3) ◽  
pp. 448-448 ◽  
Author(s):  
Bengt Hedstrom
Keyword(s):  
Newtonian Flow
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