The impact of different arrangement of molecular chains in term of low and high shear rate’s viscosities on heat and mass flow of Non-Newtonian shear thinning fluids

2021 ◽  
Vol 24 ◽  
Author(s):  
Mohsan Hassan ◽  
Abrar Faisal ◽  
Khurram Javid ◽  
Salah Ud-Din Khan ◽  
Ashfaq Ahmad ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Shear Rate ◽  
Boundary Layer Flow ◽  
Shear Thinning ◽  
High Shear Rate ◽  
High Shear ◽  
Carreau Model ◽  
Shear Thinning Fluids ◽  
Layer Flow ◽  
The Impact

Background: Non-Newtonian fluids, especially shear thinning fluids, have several applications in the polymer industry, food industry, and even in everyday life. The viscosity of shear thinning fluids is sometimes decreased by two or three orders of magnitude due to the alignment of the molecules in order when the shear rate is increased, and it cannot be ignored in the case of polymer processing and lubrication problems. Objective: So, the effects of viscosities at a low and high shear rate on the heat and mass boundary layer flow of shear thinning fluid over moving belts is investigated in this study. For this proposed, the generalized Carreau model of viscosity relates to shear rate and is used in the momentum equation. The Carreau model contains the five parameters: low shear rate viscosity, high shear rate viscosity, viscosity curvature, consistency index, and flow behavior index. For the heat flow, expression of the thermal conductivity model, similar to the viscosity equation due to the non-Newtonian nature of the fluid, is used in the energy equation. Methods: On the mathematical model of the problem, boundary layer approximations are applied and then simplified by applying the similarity transformations to get the solution. The solution of the simplified equations is obtained by numerical technique RK-Shooting Method. The results are compared with existing results for limited cases and good agreement is found. Results : The results are obtained in the form of velocity and temperature profiles under the impact of all the viscosity’s parameters and are displayed in graphical form. Moreover, the boundary layer parameters such as the thickness of the regions, momentum thickness, and displacement thickness are calculated to understand the structure of the boundary layer flow of fluid. Conclusion: The velocity and temperature of the fluid are decreased and increased respectively by all viscosity’s parameters of the model. So, the results of the boundary layer fluid flow under rheological parameters will not only help engineers to design superior chemical equipment, but will also help improve the economy and efficiency of the overall process.

scholarly journals Stability of the shear-thinning boundary-layer flow over a flat inclined plate

2017 ◽  
Vol 473 (2205) ◽  
pp. 20170350 ◽  
Author(s):  
P. T. Griffiths
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Passive Control ◽  
Shear Thinning ◽  
Base Flow ◽  
Neutral Stability ◽  
Inclined Plate ◽  
Shear Thinning Fluids ◽  
Tollmien Schlichting ◽  
Layer Flow

In this study, we consider the boundary-layer flow of an inelastic non-Newtonian fluid over an inclined flat plate. Using two popular generalized Newtonian models, we determine base flow profiles and associated linear stability results for a range shear-thinning fluids. In addition to neutral stability curves, we also present results concerning the linear growth of the Tollmien–Schlichting waves as they propagate downstream. Furthermore, to gain an insight into the underlying physical mechanisms affecting the destabilization of the disturbances, an integral energy equation is derived and energy calculations are presented. Results from all three analyses suggest that the effect of shear-thinning will act to stabilize the boundary-layer flow. Consequently, it can be argued that the addition of shear-thinning agents could act as a passive control mechanism for flows of this nature.

scholarly journals Melting Heat Transfer and MHD Boundary Layer Flow of Eyring-Powell Nanofluid Over a Nonlinear Stretching Sheet with Slip

2019 ◽  
Vol 24 (1) ◽  
pp. 161-178 ◽  
Author(s):  
N. Vijaya Bhaskar Reddy ◽  
N. Kishan ◽  
C. Srinivas Reddy
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Volume Fraction ◽  
Skin Friction Coefficient ◽  
Physical Parameters ◽  
Local Skin ◽  
Layer Flow ◽  
Nonlinear Stretching ◽  
The Impact

Abstract The steady laminar incompressible viscous magneto hydrodynamic boundary layer flow of an Eyring- Powell fluid over a nonlinear stretching flat surface in a nanofluid with slip condition and heat transfer through melting effect has been investigated numerically. The resulting nonlinear governing partial differential equations with associated boundary conditions of the problem have been formulated and transformed into a non-similar form. The resultant equations are then solved numerically using the Runge-Kutta fourth order method along with the shooting technique. The physical significance of different parameters on the velocity, temperature and nanoparticle volume fraction profiles is discussed through graphical illustrations. The impact of physical parameters on the local skin friction coefficient and rate of heat transfer is shown in tabulated form.

scholarly journals A semi-infinite hydraulic fracture driven by a shear-thinning fluid

2018 ◽  
Vol 838 ◽  
pp. 573-605 ◽  
Author(s):  
Fatima-Ezzahra Moukhtari ◽  
Brice Lecampion
Keyword(s):  
Shear Rate ◽  
Power Law ◽  
Hydraulic Fracture ◽  
Complex Structure ◽  
Shear Thinning ◽  
High Shear Rate ◽  
Asymptotic Region ◽  
High Shear ◽  
Confining Stress ◽  
Low Shear

We use the Carreau rheological model which properly accounts for the shear-thinning behaviour between the low and high shear rate Newtonian limits to investigate the problem of a semi-infinite hydraulic fracture propagating at a constant velocity in an impermeable linearly elastic material. We show that the solution depends on four dimensionless parameters: a dimensionless toughness (function of the fracture velocity, confining stress, material and fluid parameters), a dimensionless transition shear stress (related to both fluid and material behaviour), the fluid shear-thinning index and the ratio between the high and low shear rate viscosities. We solve the complete problem numerically combining a Gauss–Chebyshev method for the discretization of the elasticity equation, the quasi-static fracture propagation condition and a finite difference scheme for the width-averaged lubrication flow. The solution exhibits a complex structure with up to four distinct asymptotic regions as one moves away from the fracture tip: a region governed by the classical linear elastic fracture mechanics behaviour near the tip, a high shear rate viscosity asymptotic and power-law asymptotic region in the intermediate field and a low shear rate viscosity asymptotic far away from the fracture tip. The occurrence and order of magnitude of the extent of these different viscous asymptotic regions are estimated analytically. Our results also quantify how shear thinning drastically reduces the size of the fluid lag compared to a Newtonian fluid. We also investigate simpler rheological models (power law, Ellis) and establish the small domain where they can properly reproduce the response obtained with the complete rheology.

Characterizing the Rheology of Methane Hydrate Slurry in a Horizontal Water-Continuous System

SPE Journal ◽  
2019 ◽  
Vol 25 (03) ◽  
pp. 1026-1041 ◽  
Author(s):  
Baojiang Sun ◽  
Weiqi Fu ◽  
Zhiyuan Wang ◽  
Jianchun Xu ◽  
Litao Chen ◽  
...  
Keyword(s):  
Shear Rate ◽  
Natural Gas ◽  
Methane Hydrate ◽  
Shear Thickening ◽  
Continuous System ◽  
Shear Thinning ◽  
High Shear Rate ◽  
High Shear ◽  
Thickening Behavior ◽  
Low Shear

Summary Methane hydrate slurry in a water-continuous system is a significant production issue during pilot explorations for natural gas and natural gas hydrates in a deepwater environment. This work investigated the morphology and rheology of hydrate slurry with hydrate concentrations from 6 to 11% and shear rates from 20 to 700 s−1. Although hydrate slurry is widely considered a pseudoplastic fluid, in our experiment, hydrate slurry exhibited shear-thinning behavior in low-shear-rate conditions and shear-thickening behavior in high-shear-rate conditions. The breakup of agglomerates built up between hydrate particles by shear force induced shear-thinning behavior in low-shear-rate conditions. The collision between monodispersed hydrate particles resulted in shear-thickening behavior in high-shear-rate conditions. The critical shear rate was proposed to describe the transition between the shear-thinning and shear-thickening behaviors of the hydrate slurry, which was a function of the hydrate concentration. Empirical Herschel-Bulkley-type equations were developed to describe the rheology of the hydrate slurry for both conditions.

scholarly journals CHARACTERIZATION OF ELECTRO-RHEOLOGCIAL FLUIDS UNDER HIGH SHEAR RATE IN PARALLEL DUCTS

2008 ◽  
Vol 22 (31n32) ◽  
pp. 6029-6036 ◽  
Author(s):  
X. W. ZHANG ◽  
C. B. ZHANG ◽  
T. X. YU ◽  
W. J. WEN
Keyword(s):  
Shear Rate ◽  
Electric Field ◽  
Field Intensity ◽  
Electric Field Intensity ◽  
High Shear Rate ◽  
Shear Stresses ◽  
High Shear ◽  
Er Fluids ◽  
The Impact ◽  
Er Fluid

Electro-rheological (ER) fluid is a smart suspension which can be changed promptly from Newtonian to Bingham plastic material when subjected to a high-intensity electric field. This property of ER fluid makes it possible to be applied in adaptive energy absorbers. As the impact velocity encountered in applications could be very large, it is necessary to characterize the ERF under high shear rate. In this study, a capillary rheo-meter with parallel duct was designed and manufactured which is capable of producing a shear rate as high as 5000(1/s). Two giant ER fluids with mass concentration C = 51% and 44.5% and a commercial density-matched ER fluid with C = 37.5% were characterized. The experimental results show that when the ER fluids are free of electric field (E = 0 kV / mm ), they are Newtonian. However, for the former two ER fluids, the deposition effect is very remarkable and stirring has to be made continuously to keep the suspension stable. With the increase of the electric field intensity, the yield shear stresses of ER fluids increase exponentially but their viscosities do not change much. It is also found that within the parallel duct, the flow of ER fluids exhibits notable fluctuations, whose period increases with the increase of electric field intensity and is independent of the shear rate.

scholarly journals Improving boundary layer flow simulations over complex terrain by applying a forest parameterization in WRF

2019 ◽  
Author(s):  
Johannes Wagner ◽  
Norman Wildmann ◽  
Thomas Gerz
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Boundary Layer Flow ◽  
Complex Terrain ◽  
Potential Temperature ◽  
Short And Long Term ◽  
Layer Flow ◽  
The Impact ◽  
Double Ridge

Abstract. The impact of a forest parameterization on the simulation of boundary layer flows over complex terrain is investigated. Short- and long-term simulations are run for 12 hours and 1.5 months, respectively, with and without forest parameterization and the results are compared to lidar and meteorological tower observations. The test cases are based on the Perdigao 2017 campaign. Short-term simulations focus on low-level jet events over the double-ridge, while long-term simulations cover the whole intensive observation period of the campaign. Simulations without forest parameterization do not reproduce the interaction of the boundary layer flow with the double ridge satisfactorily. Surface winds are overestimated and flow separation and recirculation zones are not or only partly simulated. The additional drag of the forest parameterization considerably improves the agreement of simulated and observed wind speed and potential temperature by reducing the positive wind speed bias and increasing the correlation. The positive effect of the forest parameterization on the boundary layer flow is visible both in the short- and long-term simulations.

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