scholarly journals Viscous micropump of immiscible fluids using magnetohydrodynamic effects and a power-law conducting fluid

2021 ◽  
Vol 67 (6 Nov-Dec) ◽  
Author(s):  
Juan Rolando Gómez López ◽  
Clara Guadalupe Hernández Roblero ◽  
Juan Pablo Escandón Colin ◽  
René Osvaldo Vargas Aguilar
Keyword(s):  
Newtonian Fluid ◽  
Power Law ◽  
Fluid Transport ◽  
Flow Behavior ◽  
Immiscible Fluids ◽  
Conducting Fluid ◽  
Small Scale ◽  
Flat Plates ◽  
Flow Behavior Index ◽  
Interface Position

Small-scale fluid transport methods have grown significantly in recent years, mainly in applications in microfluidic systems. Therefore, the present study analyzes the movement of two-layers of immiscible fluids within a parallel flat plates microchannel. The fluid layers are composed of a Newtonian fluid and a power-law fluid. The pumping is produced by magnetohydrodynamics effects that act on the non-Newtonian conducting fluid dragging the non-conducting Newtonian fluid by viscous forces. Under the consideration of a laminar, incompressible, and unidirectional flow, the dimensionless mathematical model is established by the momentum equations for each fluid, together with the corresponding boundary conditions at solid-liquid and liquid-liquid interfaces. The problem formulation is semi-analytically solved using the Newton-Raphson method. The results are presented as a function of the velocity profiles and flow rate, showing interesting behaviors that depend on the physical and electrical properties of each fluid and flow conditions via the dimensionless parameters such as the flow behavior index, a magnetic parameter related to Lorenz forces, the fluids viscosity ratios and the dimensionless liquid-liquid interface position. This work contributes to the understanding of the various immiscible non-conducting fluids pumping techniques that can be used in microdevices.

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 COMPORTAMENTO REOLÓGICO DE EXTRATOS DE GRÃOS, FARINHA INTEGRAL E ISOLADO PROTÉICO DE SOJA

2003 ◽  
Vol 21 (2) ◽  
Author(s):  
ROSANE DA SILVA RODRIGUES ◽  
ÂNGELA MARIA GOZZO ◽  
ROBERTO HERMÍNIO MORETTI
Keyword(s):  
Newtonian Fluid ◽  
Soy Protein ◽  
Apparent Viscosity ◽  
Flow Behavior ◽  
Total Solid ◽  
Soy Flour ◽  
Soluble Solids ◽  
Rheological Parameters ◽  
Flow Behavior Index ◽  
Isolated Soy Protein

Estudou-se o comportamento reológico de extratos elaborados com grãos, farinha integral e isolado protéico de soja. Extratos com 3% de proteína foram obtidos de grãos de soja (em equipamento conhecido como “vaca mecânica”), de farinha integral e de isolado protéico (por dissolução em água) e pasteurizados a 74±2°C por 15 seg. Os parâmetros reológicos estudados foram o coeficiente de consistência, o índice de comportamento do fluxo e a viscosidade aparente. Foram determinados, também, sólidos totais, proteínas, lipídios, cinzas, fibra bruta, carboidratos e índice de sedimentação (AOAC, 1995). Verificou-se que a viscosidade aparente, a 4 e 25°C, do extrato obtido de grãos de soja (fluido nãonewtoniano com comportamento pseudoplástico) foi maior que a do extrato da farinha (fluido não-newtoniano com comportamento pseudoplástico a 4°C e dilatante a 25°C) e do isolado (fluido newtoniano). O maior índice de sedimentação constatado no extrato de farinha integral e o baixo teor de sólidos solúveis no isolado protéico foram determinantes, entre outros fatores, no comportamento reológico verificado. AbstractRHEOLOGICAL BEHAVIOR OF SOYMILK, WHOLE SOY FLOUR AND SOY ISOLATED PROTEIN The rheological properties of extracts elaborated with soybeans, whole soy flour and isolated protein were studied. Extracts with 3% of protein were obtained from soybeans (in a equipment called “mechanic cow”), whole soy flour and isolated soy protein (by dissolution in water) and pasteurized at 74±2°C for 15 seg. The rheological parameters studied were the flow behavior index, consistency coefficient and apparent viscosity. Total solid, proteins, lipids, ashes, brute fiber, carbohydrates and sedimentation index (AOAC, 1995) was also determined. The apparent viscosity, at 4 and 25°C, of the extract obtained from soybeans (non-newtonian fluid with pseudoplastic behavior), was greater than the one of whole soy flour extract (nonnewtonian fluid with pseudoplastic behavior at 4°C and dilatant at 25°C) and of the isolated soy protein extract (Newtonian fluid). The highest sedimentation index verified in the whole soy flour extract and the low content of soluble solids in the extract of isolated soy protein defined, among others factors, the rheological behavior verified.

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%.

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.

Rheological investigations of water-soluble polysaccharides extracted from Moroccan seaweed Cystoseira myriophylloides algae

2020 ◽  
Vol 11 (3-4) ◽  
pp. 49-63
Author(s):  
Soumia Zaim ◽  
Omar Cherkaoui ◽  
Halima Rchid ◽  
Rachid Nmila ◽  
Reddad El Moznine
Keyword(s):  
Rheological Properties ◽  
Power Law ◽  
Flow Behavior ◽  
Viscoelastic Behavior ◽  
Shear Thinning ◽  
Water Soluble ◽  
Flow Behavior Index ◽  
Dynamic Rheological Properties ◽  
Different Temperatures ◽  
Tan Δ

The rheological properties and spectrum infrared of polysaccharides extracted from Cystoseira myriophylloides algae were investigated in the concentrations range from 3 to 9% (w/v) and at different temperatures. Results of rheological characteristics in a steady shear rate showed pseudoplastic properties and the dynamic rheological properties showed a fluid-like viscoelastic behavior. The flow and viscoelastic characteristics of polysaccharides were described using the power-law (the Ostwald model). The values of flow behavior index of the sample were close to unity (0.91) for 3% and it decreased up to 0.71 for 9% revealing the shear-thinning (pseudoplastic) nature of these polysaccharides. Moreover, the consistency coefficient increased non-linearly with concentration and it was described by a power law. The flow behavior as a function of temperature was satisfactorily described using the Arrhenius law and the activation energy values were extracted. It decreased from 15.68 and 17.21 kJ/mol when the concentration increased from 5 to 9% (w/v). Additionally, in dynamic rheological measurements, tan δ > 1 and G″ > G′ reveling a shear-thinning behavior. Finally, the analysis of the FTIR spectra of these polysaccharides showed the presence of uronic acid groups. This behavior would suggest that polysaccharides extracted from Cystoseira myriophylloides could be an interesting additive as thickeners.

An Approximate Analytical Solution for Electro-Osmotic Flow of Power-Law Fluids in a Planar Microchannel

2011 ◽  
Vol 133 (9) ◽  
Author(s):  
Arman Sadeghi ◽  
Moslem Fattahi ◽  
Mohammad Hassan Saidi
Keyword(s):  
Nusselt Number ◽  
Power Law ◽  
Flow Behavior ◽  
Heat Fluxes ◽  
Flow Behavior Index ◽  
Osmotic Flow ◽  
Flow Parameters ◽  
Wall Heating ◽  
Power Law Fluids ◽  
Electro Osmotic Flow

The present investigation considers the fully developed electro-osmotic flow of power-law fluids in a planar microchannel subject to constant wall heat fluxes. Using an approximate velocity distribution, closed form expressions are obtained for the transverse distribution of temperature and Nusselt number. The approximate solution is found to be quite accurate, especially for the values of higher than ten for the dimensionless Debye-Huckel parameter where the exact values of Nusselt number are predicted. The results demonstrate that a higher value of the dimensionless Debye-Huckel parameter is accompanied by a higher Nusselt number for wall cooling, whereas the opposite is true for wall heating case. Although to increase the dimensionless Joule heating term is to decrease Nusselt number for both pseudoplastic and dilatant fluids, nevertheless its effect on Nusselt number is more pronounced for dilatants. Furthermore, to increase the flow behavior index is to decrease the Nusselt number for wall cooling, whereas the contrary is right for the wall heating case. Depending on the value of flow parameters, a singularity is observed in the Nusselt number values of the wall heating case.

scholarly journals Flow Behavior of Power-Law Non-Newtonian Fluid in a Grooved Rotating-Disk Dynamic Filter without Permeation.

1992 ◽  
Vol 18 (4) ◽  
pp. 487-494 ◽  
Author(s):  
Haruo Yamazaki ◽  
Toshiro Murase ◽  
Masashi Iwata ◽  
Mompei Shirato
Keyword(s):  
Newtonian Fluid ◽  
Power Law ◽  
Flow Behavior ◽  
Rotating Disk ◽  
Dynamic Filter

scholarly journals Electroosmotic Mixing of Non-Newtonian Fluid in a Microchannel with Obstacles and Zeta Potential Heterogeneity

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 431
Author(s):  
Lanju Mei ◽  
Defu Cui ◽  
Jiayue Shen ◽  
Diganta Dutta ◽  
Willie Brown ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Newtonian Fluid ◽  
Stokes Equations ◽  
Flow Behavior ◽  
Vortical Flow ◽  
Mixing Efficiency ◽  
Flow Behavior Index ◽  
Fluid Field ◽  
Electric Double Layer Thickness ◽  
Behavior Index

This paper investigates the electroosmotic micromixing of non-Newtonian fluid in a microchannel with wall-mounted obstacles and surface potential heterogeneity on the obstacle surface. In the numerical simulation, the full model consisting of the Navier–Stokes equations and the Poisson–Nernst–Plank equations are solved for the electroosmotic fluid field, ion transport, and electric field, and the power law model is used to characterize the rheological behavior of the aqueous solution. The mixing performance is investigated under different parameters, such as electric double layer thickness, flow behavior index, obstacle surface zeta potential, obstacle dimension. Due to the zeta potential heterogeneity at the obstacle surface, vortical flow is formed near the obstacle surface, which can significantly improve the mixing efficiency. The results show that, the mixing efficiency can be improved by increasing the obstacle surface zeta potential, the flow behavior index, the obstacle height, the EDL thickness.

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.

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