Some Discussions on the Flow Factor Tensor—Considerations of Roughness Orientation and Flow Rheology

2000 ◽  
Vol 122 (4) ◽  
pp. 869-872 ◽  
Author(s):  
Wang-Long Li
Keyword(s):  
Power Law ◽  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
Flow Behavior ◽  
Mapping Function ◽  
Power Law Fluid ◽  
Flow Behavior Index ◽  
Random Roughness ◽  
Flow Factor ◽  
Behavior Index

Relations expressing the effects of roughness orientations θi and flow behavior index n of the power-law fluid on the flow factors of area-distributed random roughness in hydrodynamic lubrication are derived. By using a mapping function, the generalized average Reynolds equation contains non-diagonal terms, and the flow factor tensor is symmetrical but not necessarily diagonal according to the coordinate system. Finally, the conditions that two rough surfaces act as though they were perfectly smooth are discussed for some particular combinations. [S0742-4787(00)01604-0]

Flow Resistance and Mass Transfer in Slow Non-Newtonian Flow Through Multiparticle Systems

1992 ◽  
Vol 59 (2) ◽  
pp. 431-437 ◽  
Author(s):  
M. G. Satish ◽  
J. Zhu
Keyword(s):  
Mass Transfer ◽  
Fluid Flow ◽  
Power Law ◽  
Cell Model ◽  
Flow Behavior ◽  
Solid Sphere ◽  
Power Law Fluid ◽  
Flow Behavior Index ◽  
Flow Through ◽  
Behavior Index

Finite difference solutions for a power-law fluid flow through an assemblage of solid particles at low Reynolds numbers are obtained using both the free-surface cell model and the zero-vorticity cell model. It is shown that, unlike in the case of power-law fluid flow past a single solid sphere, the flow drag decreases with decrease of flow behavior index, and that the degree of this reduction is more significant at low voidage. The results from this study are found to be in good agreement with the approximate solutions at slight pseudoplastic anomaly and the available experimental data. The results are presented in closed form and compare favorably with the variational bounds and the modified Blake-Kozeny equations. Numerical results show that a decrease in the flow behavior index leads to a slight increase in the mass transfer rate for an assemblage of solid spheres, but this increase is found to be small compared with that for a single solid sphere.

Note: Rheological changes in cooked cornmeal dough due to differences in moisture content using squeezing flow viscometry/Nota: Efecto del contenido de húmedad en las propiedades reológicas de masa de maíz cocida usando viscometría de compresión entre dos platos lubricados

1995 ◽  
Vol 1 (1) ◽  
pp. 41-45 ◽  
Author(s):  
R.G. Moreira ◽  
T.-Er Lo ◽  
M.E. Castell-Perez
Keyword(s):  
Moisture Content ◽  
Power Law ◽  
Flow Behavior ◽  
Elongational Viscosity ◽  
Squeezing Flow ◽  
Power Law Fluid ◽  
Flow Behavior Index ◽  
Lubricated Squeezing Flow ◽  
Food Processes ◽  
Behavior Index

The elongational viscosity of two different cooked cornmeal dough was determined as a function of moisture content (55-70% wet basis) and differences in cornmeal structure using the lubricated squeezing flow technique. When the flow regime was not governed by the viscoelastic effect, cooked cornmeal dough could be described as a power-law fluid with a flow behavior index, n, of 0.418-0.473 and consistency coefficient, K, ranging from 18.7 to 85.0 kPa s". Regression results indicated that K increased exponentially as moisture content decreased. Results suggested that the technique can be used to characterize the flow behavior and viscosity values of cooked cornmeal dough for further use in control of food processes such as extrusion.

Electroosmotic Flow of Power-Law Fluids in a Slit Microchannel

2009 ◽  
Author(s):  
Cunlu Zhao ◽  
Chun Yang
Keyword(s):  
Shear Stress ◽  
Double Layer ◽  
Power Law ◽  
Dynamic Viscosity ◽  
Electroosmotic Flow ◽  
Flow Behavior ◽  
Flow Behavior Index ◽  
Power Law Fluids ◽  
Hyperbolic Cosine ◽  
Behavior Index

Electroosmotic flow of power-law fluids in a slit channel is analyzed. The governing equations including the linearized Poisson–Boltzmann equation, the Cauchy momentum equation and the continuity equation are solved to seek analytical expressions for the shear stress, dynamic viscosity and velocity distributions. Specifically, exact solutions of the velocity distributions are explicitly found for several special values of the flow behavior index. Furthermore, with the implementation of an approximate scheme for the hyperbolic cosine function, approximate solutions of the velocity distributions are obtained. In addition, a mathematical expression for the average electroosmotic velocity is derived for large values of the dimensionless electrokinetic parameter, κH, in a fashion similar to the Smoluchowski equation. Hence, a generalized Smoluchowski velocity is introduced by taking into account contributions due to the finite thickness of the electric double layer and the flow behavior index of power-law fluids. Finally, calculations are performed to examine the effects of κH, flow behavior index, double layer thickness, and applied electric field on the shear stress, dynamic viscosity, velocity distribution, and average velocity/flow rate of the electroosmotic flow of power-law fluids.

scholarly journals Uncertainties quantification and modelling of different rheological models in estimation of pressure losses during drilling operation

2018 ◽  
Vol 7 (2) ◽  
pp. 694 ◽  
Author(s):  
Anawe P. A. L ◽  
Folayan J. Adewale
Keyword(s):  
Power Law ◽  
Averaging Method ◽  
Graphical Method ◽  
Flow Behavior ◽  
Drilling Fluids ◽  
Flow Behavior Index ◽  
Rheological Models ◽  
Pressure Losses ◽  
Pump Pressure ◽  
Behavior Index

The determination of pressure losses in the drill pipe and annulus with a very high degree of precision and accuracy is sacrosanct for proper pump operating conditions and correct bit nozzle sizes for maximum jet impact and forestalling of possible kicks and eventual blow outs during drilling operation. The two major uncertainties in pump pressure estimation that are being addressed in this research work are the flow behavior index (n) and the consistency index factor (k). It is in this light that the accuracy of various rheological models in predicting pump pressure losses as well as the uncertainties associated with each model was investigated. In order to come by with a decisive conclusion, two synthetic based drilling fluids were used to form synthetic muds known as sample A and B respectively. Inference from results shows that the Newtonian model underestimated the pump pressure by 78.27% for sample A and 82.961% by for sample B. While the Bingham plastic model overestimated the total pump pressure by 100.70% for sample A and 48.17% for sample B. Three different power law rheological model approaches were used to obtain the flow behavior index and consistency factor of the drilling fluids. For the power law rheological model approaches, an underestimation error of 23.5743% was encountered for the Formular method for sample A while the proposed consistency index averaging method reduces the error to 14.9306%. The Graphical method showed a reasonable degree of accuracy with underestimation error of 5.6435%. Sample B showed an underestimation error of 47.8234% by using the power law formula method while the Consistency averaging method reduced the error to 20.7508. The graphical method showed an underestimation error of 0.4318%.

A Comparative Analysis of Mixing Performance of Power-Law Fluid in Cylindrical Microchannels With Sudden Contraction/Expansion

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
A. Banerjee ◽  
A. K. Nayak ◽  
B. Weigand
Keyword(s):  
Pressure Drop ◽  
Power Law ◽  
Flow Behavior ◽  
Geometric Parameters ◽  
Mixing Efficiency ◽  
Flow Behavior Index ◽  
Mixing Performance ◽  
Geometric Configurations ◽  
Wide Range ◽  
Behavior Index

Abstract This paper focuses on the comparative electrokinetic micromixing of non-Newtonian fluid in cylindrical microchannels with surface potential heterogeneity due to sudden constriction/expansion. In numerical simulations, the rheology of the aqueous solution is considered to follow power-law characteristic. Based on the Poisson–Nernst–Planck model, the simulations are performed to investigate the mixing efficiency and pressure drop for constricted and expanded configurations over a wide range of the flow behavior index, potential patch strength, and geometric parameters. The results show that, irrespective of geometric configurations, the mixing efficiency can be improved significantly by increasing the flow behavior index, geometric parameters, and the overpotential patch strength. In addition, it is also revealed that the constricted geometry yields better mixing as compared to the other configuration, but the average pressure drop shows reverse characteristics. Thus, a parametric relationship is tried to be established between mixing efficiency and pressure drop for both these configurations to propose an effective and efficient micromixer, which can produce maximum possible mixing efficiency with minimum pressure drop.

Static Rheological Study of Ocimum basilicum Seed Gum

2015 ◽  
Vol 11 (1) ◽  
pp. 97-103 ◽  
Author(s):  
Fakhreddin Salehi ◽  
Mahdi Kashaninejad
Keyword(s):  
Power Law ◽  
Flow Behavior ◽  
Shear Thinning ◽  
Power Law Model ◽  
Rotational Viscometer ◽  
Flow Behavior Index ◽  
Consistency Coefficient ◽  
Salt Addition ◽  
Seed Gum ◽  
Behavior Index

Abstract A rotational viscometer was used to investigate the effect of different sugars (sucrose, glucose, fructose and lactose, 1–4% w/w) and salts (NaCl and CaCl2, 0.1–1% w/w), on rheological properties of Basil seed gum (BSG). The viscosity was dependent on type of sugar and salt addition. Interactions between BSG gum and sugars improved the viscosity of solutions, whereas the viscosity of the BSG solutions decreased in the presence of salts. Power law model well-described non-Newtonian shear thinning behavior of BSG. The consistency index was influenced by the sugars and salts content. Addition of sucrose, glucose, lactose and salts to BSG led to increases in flow behavior index (less shear thinning solutions), whereas fructose increased shear thinning of solutions. Flow behavior index values of the power law model vary as follows: 0.43–0.49, 0.53–0.64, 0.21–0.26, and 0.57–0.67 for sucrose, glucose, fructose and lactose, respectively. The consistency coefficient (k) of BSG was affected by sugars and salts. It decreased from 0.14 to 0.09 Pa.sn with increasing CaCl2 from 0 to 4% w/w (20°C, 0.2% w/w BSG). The consistency coefficient values vary as follows: 0.094–0.119, 0.075–0.098, 0.257–0.484, and 0.056–0.074 for sucrose, glucose, fructose and lactose, respectively.

Solutions of Laminar Jet Flow Problems for Non-Newtonian Power-Law Fluids

1978 ◽  
Vol 100 (3) ◽  
pp. 363-366 ◽  
Author(s):  
E. M. Mitwally
Keyword(s):  
Power Law ◽  
Flow Behavior ◽  
Flow Behavior Index ◽  
Free Jets ◽  
Free Jet ◽  
Laminar Jet ◽  
Flow Problems ◽  
Power Law Fluids ◽  
Flow Configurations ◽  
Behavior Index

Solutions are presented for laminar flow of non-Newtonian power-law fluids. The flow configurations cover the two-dimensional plane and radial free jets, the axisymmetrical (circular) free jet, and the plane and radial wall jets. When the flow behavior index is unity, the present results agree well with those already published for the case of Newtonian fluids.

Elastohydrostatic Lubrication of Circular Plate Thrust Bearing With Power Law Lubricants

1982 ◽  
Vol 104 (2) ◽  
pp. 243-247 ◽  
Author(s):  
Chandan Singh ◽  
T. S. Nailwal ◽  
Prawal Sinha
Keyword(s):  
Circular Plate ◽  
Power Law ◽  
Load Capacity ◽  
Flow Behavior ◽  
Elastic Parameter ◽  
Flow Behavior Index ◽  
Thrust Bearings ◽  
Rate Of Increase ◽  
Film Profile ◽  
Behavior Index

The problem of elastohydrostatic lubrication of circular plate thrust bearings is analyzed with non-Newtonian power law lubricants. It is seen that the elastic layer on the surface improves the bearing performance for all values of the flow behavior index n. The load is found to increase for all values of n and the rate of increase of load capacity at a given elastic parameter is higher for higher values of n. The film profile departs from its unloaded shape for an elastic layered surface and the departure is higher for small values of n.

Numerical Simulation of Large-Diameter Annular Pressure Loss in Riser Segment of Deep-Water Drilling

2013 ◽  
Vol 868 ◽  
pp. 510-516
Author(s):  
Yang Liu ◽  
Guo Cheng Zhang
Keyword(s):  
Numerical Simulation ◽  
Pressure Loss ◽  
Rotation Speed ◽  
Flow Behavior ◽  
Large Diameter ◽  
Drill Pipe ◽  
Marine Riser ◽  
Power Law Fluid ◽  
Flow Behavior Index ◽  
Behavior Index

Large-diameter annulus and conventional annulus are very different in hydraulic property. Based on numerical simulation, a study on pressure loss of large-diameter annulus was carried out. The influence of annular velocity, pipes rotation speed, mud property and annular diameter of marine riser segment on pressure loss was also analyzed and compared with that of conventional segment. The results show that under the condition of large-diameter annulus, the pressure loss of power law fluid laminar flow decreases with the increase of the rotational speed of drill pipe and the contrary tendency occurred when it is turbulent flow. With the increase of the flow behavior index and consistency coefficient, annular pressure loss increases exponentially and linearly respectively. From an overall perspective, with the increase of annular size, the annular pressure loss sharply reduced, and it has great effect on pressure loss.

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