scholarly journals Two-phase power-law modeling of pipe flows displaying shear-thinning phenomena

1993 ◽  
Author(s):  
Jianmin Ding ◽  
R.W. Lyczkowski ◽  
W.T. Sha
Keyword(s):  
Power Law ◽  
Shear Thinning ◽  
Two Phase ◽  
Pipe Flows

A Rational Friction Factor Correlation for Laminar Fully-Developed Pipe Flows of Shear-Thinning Non-Newtonian Fluids

2021 ◽  
Author(s):  
Robert Brewster
Keyword(s):  
Shear Rate ◽  
Friction Factor ◽  
Power Law ◽  
Fluid Model ◽  
Shear Thinning ◽  
Newtonian Fluids ◽  
Cross Model ◽  
Pipe Flows ◽  
Design Calculations ◽  
Friction Factor Correlation

Abstract A friction factor correlation for laminar, hydrodynamically fully-developed pipe flows of shear-thinning non-Newtonian fluids is derived through analysis and asymptotic considerations. The specific non-Newtonian fluid model used is the Extended Modified Power Law (EMPL) model, which is functionally equivalent to the Cross model. The EMPL model spans the entire shear rate range from the low to the high shear rate Newtonian regions, and includes the intermediate shear rate power law region. The friction factor correlation has an explicit form and is a function of three dimensionless parameters, making it well-suited to design calculations. The overall accuracy of the correlation is 6.6%, though it is much better in most cases. Graphical results for the correlation, and deviations with respect to high-accuracy numerical calculations are presented and discussed.

Rheological studies of functional polyurethane composite

2017 ◽  
Vol 50 (3) ◽  
pp. 222-240
Author(s):  
Sayavur I Bakhtiyarov ◽  
Jimmie C Oxley ◽  
James L Smith ◽  
Philipp M Baldovi
Keyword(s):  
Newtonian Fluid ◽  
Power Law ◽  
Effective Viscosity ◽  
Aluminum Content ◽  
Fluid Model ◽  
Shear Thinning ◽  
Testing Time ◽  
Two Phase ◽  
Bingham Plastic ◽  
Polyurethane Composite

The rheological dynamic characteristics of the functional Polyurethane composite as well as its compounds ( triethanolamine (TEOA) and toluene-2,4-diisocyanate (TDI)) with and without solid additives (aluminum flakes) were experimentally measured using a computer-controlled mechanical spectrometer (rheometer) ARES-G2. Rheological studies showed that both components behave as viscous Newtonian fluids. TEOA exhibits a strong temperature-thickening behavior. TEOA with aluminum flake additives behaves as a viscous Newtonian fluid. The effective viscosity of the two-phase mixture increases with the concentration of the aluminum additive and decreases with the temperature rise. The rheometric tests showed that the effective viscosity of the TDI/Al mixture increases with the aluminum content. The mixture exhibits thermal-thickening and shear-thinning behaviors with the yield stress. The system can be described with the Bingham plastic model. It is determined that TEOA/TDI composite exhibits a strong time-thickening and shear-thinning behaviors. The rheological behavior of this composite can be described with the power-law generalized non-Newtonian fluid model. The effective viscosity of TEOA/TDI/Al composite increases with both the testing time (exponentially) and the aluminum content (polynomial) in the mixture. However, these shear-thinning composites obey the power-law generalized non-Newtonian fluid model, and their flow curves can be described by the logarithmic law.

Drop Coagulation in Cross-Over Pipe Flows of Wet Steam

1979 ◽  
Vol 21 (5) ◽  
pp. 357-360 ◽  
Author(s):  
J. J. E. Williams ◽  
R. I. Crane
Keyword(s):  
Drop Size ◽  
Chemical Engineering ◽  
Numerical Technique ◽  
Wet Steam ◽  
Coagulation Rate ◽  
Two Phase ◽  
Size Spectra ◽  
Pipe Flows ◽  
The Core ◽  
Median Diameter

A numerical technique is developed for predicting the evolution of drop-size spectra in turbulent, two-phase pipe flows. While relevant to many chemical engineering processes, it is applied here to the crossover pipes of a nuclear wet-steam turbine. Valid expressions for turbulent coagulation rate in the cross-over pipes are available only for drops below about 10 μm diameter in the core flow, and for those exceeding about 20 μm near the pipe wall. Using these expressions, it is found that the rapid formation of large drops in the core allows prediction for only a small fraction of the typical residence time in the pipe, but near the wall the volume median diameter of an initial 20 μm monodispersion can double in 100 ms. Further work is required to validate the technique and extend it to handle the intervening ranges of drop size and turbulence parameters.

Drag on a Sphere in Poiseuille Flow of Shear-Thinning Power-Law Fluids

2011 ◽  
Vol 50 (23) ◽  
pp. 13105-13115 ◽  
Author(s):  
Daoyun Song ◽  
Rakesh K. Gupta ◽  
Rajendra P. Chhabra
Keyword(s):  
Power Law ◽  
Poiseuille Flow ◽  
Shear Thinning ◽  
Power Law Fluids

scholarly journals Effects of Two Phase Turbulent Structure Interactions on Phase Distribution in Bubbly Pipe Flows.

1999 ◽  
Vol 42 (3) ◽  
pp. 419-428 ◽  
Author(s):  
T.C. KUO ◽  
A.S. YANG ◽  
C. PAN ◽  
C.C. CHIENG
Keyword(s):  
Phase Distribution ◽  
Turbulent Structure ◽  
Two Phase ◽  
Pipe Flows

Heat Transfer Enhancement in Annular Shear-Thinning Flows Over a Sudden Pipe Expansion

2017 ◽  
Author(s):  
Khaled J. Hammad
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Power Law ◽  
Shear Thinning ◽  
Diameter Ratio ◽  
Transfer Enhancement ◽  
Heat Transfer Augmentation ◽  
Prandtl Numbers ◽  
Power Law Index ◽  
The Impact

Heat transfer enhancement in suddenly expanding annular pipe flows of a shear-thinning non-Newtonian fluid is studied within the steady laminar flow regime. Conservation of mass, momentum, and energy equations, along with the power-law constitutive model are numerically solved. The impact of inflow inertia, annular-nozzle-diameter-ratio, k, power-law index, n, and Prandtl numbers, is reported for: Re = {50, 100}, k = {0, 0.5, 0.7}; n = {1, 0.8, 0.6}; and Pr = {1, 10, 100}. Heat transfer enhancement downstream of the expansion plane, i.e., Nusselt numbers, Nu, higher than the fully developed value, in the downstream pipe, is observed only for Pr = 10 and 100. Higher Prandtl numbers, power-law index values, and annular diameter ratios, in general, reflect a more dramatic heat transfer augmentation downstream of the expansion plane. Heat transfer augmentation for Pr = 10 and 100, is more dramatic for suddenly expanding annular flows, in comparison with suddenly expanding pipe flow. For a given annular diameter ratio and Reynolds numbers, increasing the Prandtl number from Pr = 10 to Pr = 100, always results in higher peak Nu values, for both Newtonian and shear-thinning non-Newtonian flows.

Study of Blood Flow in Micro-Channels Using Mixture Theory

2014 ◽  
Author(s):  
Wei-Tao Wu ◽  
Nadine Aubry ◽  
James F. Antaki ◽  
Mehrdad Massoudi
Keyword(s):  
Blood Flow ◽  
Newtonian Fluid ◽  
Mixture Theory ◽  
Shear Thinning ◽  
Characteristic Size ◽  
Navier Stokes ◽  
Two Phase ◽  
Plasma Skimming ◽  
Micro Channels ◽  
Complex Phenomena

It is known that in large vessels (whole) blood behaves as a Navier-Stokes (Newtonian) fluid; however, in a vessel whose characteristic dimension (e.g., a diameter in the range of 20 to 500 microns) is about the same size as the characteristic size of the blood cells, blood behaves as a non-Newtonian fluid, exhibiting complex phenomena, such as shear-thinning, stress relaxation, the Fahraeus effect, the plasma-skimming, etc.. Using the framework of mixture theory an Eulerian-Eulerian two phase model is applied to model blood flow, where the plasma is treated as Newtonian fluid and the RBCs are treated as shear thinning fluid.[5]

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