scholarly journals Cu and Cu-SWCNT Nanoparticles’ Suspension in Pulsatile Casson Fluid Flow via Darcy–Forchheimer Porous Channel with Compliant Walls: A Prospective Model for Blood Flow in Stenosed Arteries

2021 ◽  
Vol 22 (12) ◽  
pp. 6494
Author(s):  
Amjad Ali ◽  
Zainab Bukhari ◽  
Muhammad Umar ◽  
Muhammad Ali Ismail ◽  
Zaheer Abbas
Keyword(s):  
Reynolds Number ◽  
Blood Flow ◽  
Fluid Flow ◽  
Peclet Number ◽  
Casson Fluid ◽  
Porous Channel ◽  
Péclet Number ◽  
Compliant Walls ◽  
The Impact ◽  
Prospective Model

The use of experimental relations to approximate the efficient thermophysical properties of a nanofluid (NF) with Cu nanoparticles (NPs) and hybrid nanofluid (HNF) with Cu-SWCNT NPs and subsequently model the two-dimensional pulsatile Casson fluid flow under the impact of the magnetic field and thermal radiation is a novelty of the current study. Heat and mass transfer analysis of the pulsatile flow of non-Newtonian Casson HNF via a Darcy–Forchheimer porous channel with compliant walls is presented. Such a problem offers a prospective model to study the blood flow via stenosed arteries. A finite-difference flow solver is used to numerically solve the system obtained using the vorticity stream function formulation on the time-dependent governing equations. The behavior of Cu-based NF and Cu-SWCNT-based HNF on the wall shear stress (WSS), velocity, temperature, and concentration profiles are analyzed graphically. The influence of the Casson parameter, radiation parameter, Hartmann number, Darcy number, Soret number, Reynolds number, Strouhal number, and Peclet number on the flow profiles are analyzed. Furthermore, the influence of the flow parameters on the non-dimensional numbers such as the skin friction coefficient, Nusselt number, and Sherwood number is also discussed. These quantities escalate as the Reynolds number is enhanced and reduce by escalating the porosity parameter. The Peclet number shows a high impact on the microorganism’s density in a blood NF. The HNF has been shown to have superior thermal properties to the traditional one. These results could help in devising hydraulic treatments for blood flow in highly stenosed arteries, biomechanical system design, and industrial plants in which flow pulsation is essential.

scholarly journals Effect of aligned magnetic field on Casson fluid flow over a stretched surface of non-uniform thickness

2019 ◽  
Vol 8 (1) ◽  
pp. 283-292 ◽  
Author(s):  
R. Saravana ◽  
M. Sailaja ◽  
R. Hemadri Reddy
Keyword(s):  
Magnetic Field ◽  
Fluid Flow ◽  
Casson Fluid ◽  
Uniform Thickness ◽  
Flow Energy ◽  
Cross Diffusion ◽  
Flow Situation ◽  
Matlab Package ◽  
The Impact ◽  
Aligned Magnetic Field

Abstract In the study, we inspect the impact of cross diffusion and aligned magnetic field on Casson fluid flow along a stretched surface of variable thickness. The differential equations explaining the flow situation have been transitioned with the succor of suited transfigurations. The solution of the problem is achieved by using bvp5c Matlab package. From the solution, it is perceived that the flow, temperature and concentration fields are affected by the sundry physical quantities. Results explored for the flow over a uniform and a non-uniform thickness surfaces. The influence of emerging parameters on the flow, energy and mass transport are discussed with graphical and tabular results. Results show that the thermal, flow and species boundary layers are uneven for the flow over a uniform and non-uniform thickness stretched surfaces.

Numerical Analysis of Heat Transfer Enhancement in a Micro-Channel Due to Mechanical Stirrers

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
M. Sreejith ◽  
S. Chetan ◽  
S. N. Khaderi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Enhancement ◽  
Peclet Number ◽  
Periodic Case ◽  
Two Dimensional ◽  
Transfer Enhancement ◽  
Fluidic Channel ◽  
Enhancement Of Heat Transfer ◽  
Péclet Number

Abstract Using two-dimensional numerical simulations of the momentum, mass, and energy conservation equations, we investigate the enhancement of heat transfer in a rectangular micro-fluidic channel. The fluid inside the channel is assumed to be stationary initially and actuated by the motion imparted by mechanical stirrers, which are attached to the bottom of the channel. Based on the direction of the oscillation of the stirrers, the boundary conditions can be classified as either no-slip (when the oscillation is perpendicular to the length of the channel) or periodic (when the oscillation is along the length of the channel). The heat transfer enhancement due to the motion of the stirrers (with respect to the stationary stirrer situation) is analyzed in terms of the Reynolds number (ranging from 0.7 to 1000) and the Peclet number (ranging from 10 to 100). We find that the heat transfer first increases and then decreases with an increase in the Reynolds number for any given Peclet number. The heat transferred is maximum at a Reynolds number of 20 for the no-slip case and at a Reynolds number of 40 for the periodic case. For a given Peclet and Reynolds number, the heat flux for the periodic case is always larger than the no-slip case. We explain the reason for these trends using time-averaged flow velocity profiles induced by the oscillation of the mechanical stirrers.

scholarly journals Flow "reflexion" and " refraction" on perforated wall

2019 ◽  
Vol 213 ◽  
pp. 02085
Author(s):  
Vaclav Tesař
Keyword(s):  
Reynolds Number ◽  
Fluid Flow ◽  
Cross Section ◽  
Oblique Impact ◽  
The Other ◽  
Perforated Wall ◽  
Spatially Periodic ◽  
Oval Cross Section ◽  
The Impact

This article presents some results accumulated by author during investigation of an oblique impact of fluid flow on a wall consisting of a spatially periodic rods of very simple oval cross section. The flowfield in the vicinity of the impact is quite complex and strongly Reynolds -number dependent. A part of the jet downstream from the impact is “reflected” from the wall — while the rest, which passes through the empty spaces between the cascade members, leaves the other wall side in what appears to be “refraction” direction.

Entropy generation and heat transport analysis of Casson fluid flow with viscous and Joule heating in an inclined porous microchannel

2019 ◽  
Vol 233 (5) ◽  
pp. 1173-1184 ◽  
Author(s):  
BJ Gireesha ◽  
CT Srinivasa ◽  
NS Shashikumar ◽  
Madhu Macha ◽  
JK Singh ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Entropy Generation ◽  
Convective Boundary Condition ◽  
Casson Fluid ◽  
Entropy Generation Rate ◽  
Bejan Number ◽  
Convective Boundary ◽  
Electrically Conducting ◽  
Number Formula ◽  
The Impact

The combined effects of the magnetic field, suction/injection, and convective boundary condition on heat transfer and entropy generation in an electrically conducting Casson fluid flow through an inclined porous microchannel are scrutinized. The temperature-dependent heat source is also accounted. Numerical simulation for the modelled problem is presented via Runge–Kutta–Felhberg-based shooting technique. Special attention is given to analyze the impact of involved parameters on the profiles of velocity [Formula: see text], temperature [Formula: see text], entropy generation [Formula: see text], and Bejan number [Formula: see text]. It is established that entropy generation rate decreases at the walls with an increase in Hartmann number [Formula: see text], while it increases at the center region of the microchannel.

Passive scalar statistics in high-Péclet-number grid turbulence

1998 ◽  
Vol 358 ◽  
pp. 135-175 ◽  
Author(s):  
L. MYDLARSKI ◽  
Z. WARHAFT
Keyword(s):  
Reynolds Number ◽  
Velocity Field ◽  
Peclet Number ◽  
Passive Scalar ◽  
Structure Functions ◽  
Order Structure ◽  
Grid Turbulence ◽  
Temperature Derivative ◽  
Péclet Number ◽  
Transverse Temperature

The statistics of a turbulent passive scalar (temperature) and their Reynolds number dependence are studied in decaying grid turbulence for the Taylor-microscale Reynolds number, Rλ, varying from 30 to 731 (21[les ]Peλ[les ]512). A principal objective is, using a single (and simple) flow, to bridge the gap between the existing passive grid-generated low-Péclet-number laboratory experiments and those done at high Péclet number in the atmosphere and oceans. The turbulence is generated by means of an active grid and the passive temperature fluctuations are generated by a mean transverse temperature gradient, formed at the entrance to the wind tunnel plenum chamber by an array of differentially heated elements. A well-defined inertial–convective scaling range for the scalar with a slope, nθ, close to the Obukhov–Corrsin value of 5/3, is observed for all Reynolds numbers. This is in sharp contrast with the velocity field, in which a 5/3 slope is only approached at high Rλ. The Obukhov–Corrsin constant, Cθ, is estimated to be 0.45–0.55. Unlike the velocity spectrum, a bump occurs in the spectrum of the scalar at the dissipation scales, with increasing prominence as the Reynolds number is increased. A scaling range for the heat flux cospectrum was also observed, but with a slope around 2, less than the 7/3 expected from scaling theory. Transverse structure functions of temperature exist at the third and fifth orders, and, as for even-order structure functions, the width of their inertial subranges dilates with Reynolds number in a systematic way. As previously shown for shear flows, the existence of these odd-order structure functions is a violation of local isotropy for the scalar differences, as is the existence of non-zero values of the transverse temperature derivative skewness (of order unity) and hyperskewness (of order 100). The ratio of the temperature derivative standard deviation along and normal to the gradient is 1.2±0.1, and is independent of Reynolds number. The refined similarity hypothesis for the passive scalar was found to hold for all Rλ, which was not the case for the velocity field. The intermittency exponent for the scalar, μθ, was found to be 0.25±0.05 with a possible weak Rλ dependence, unlike the velocity field, where μ was a strong function of Reynolds number. New, higher-Reynolds-number results for the velocity field, which smoothly follow the trends of Mydlarski & Warhaft (1996), are also presented.

Dispersion controlled by permeable surfaces: surface properties and scaling

2016 ◽  
Vol 801 ◽  
pp. 13-42 ◽  
Author(s):  
Bowen Ling ◽  
Alexandre M. Tartakovsky ◽  
Ilenia Battiato
Keyword(s):  
Mass Transport ◽  
Solute Transport ◽  
Surface Properties ◽  
Peclet Number ◽  
Dispersion Coefficient ◽  
Operating Conditions ◽  
Péclet Number ◽  
Porosity And Permeability ◽  
Matrix Porosity ◽  
The Impact

Permeable and porous surfaces are common in natural and engineered systems. Flow and transport above such surfaces are significantly affected by the surface properties, e.g. matrix porosity and permeability. However, the relationship between such properties and macroscopic solute transport is largely unknown. In this work, we focus on mass transport in a two-dimensional channel with permeable porous walls under fully developed laminar flow conditions. By means of perturbation theory and asymptotic analysis, we derive the set of upscaled equations describing mass transport in the coupled channel–porous-matrix system and an analytical expression relating the dispersion coefficient with the properties of the surface, namely porosity and permeability. Our analysis shows that their impact on the dispersion coefficient strongly depends on the magnitude of the Péclet number, i.e. on the interplay between diffusive and advective mass transport. Additionally, we demonstrate different scaling behaviours of the dispersion coefficient for thin or thick porous matrices. Our analysis shows the possibility of controlling the dispersion coefficient, i.e. transverse mixing, by either active (i.e. changing the operating conditions) or passive mechanisms (i.e. controlling matrix effective properties) for a given Péclet number. By elucidating the impact of matrix porosity and permeability on solute transport, our upscaled model lays the foundation for the improved understanding, control and design of microporous coatings with targeted macroscopic transport features.

scholarly journals Flow Rate Prediction for a Semi-permeable Membrane at Low Reynolds Number in a Circular Pipe

2021 ◽  
Author(s):  
Suguru Miyauchi ◽  
Shuji Yamada ◽  
Shintaro Takeuchi ◽  
Asahi Tazaki ◽  
Takeo Kajishima
Keyword(s):  
Reynolds Number ◽  
Osmotic Pressure ◽  
Membrane Permeability ◽  
Flow Rate ◽  
Peclet Number ◽  
Concentration Polarization ◽  
Circular Pipe ◽  
Permeate Flux ◽  
Permeable Membrane ◽  
Péclet Number

AbstractA concise and accurate prediction method is required for membrane permeability in chemical engineering and biological fields. As a preliminary study on this topic, we propose the concentration polarization model (CPM) of the permeate flux and flow rate under dominant effects of viscosity and solute diffusion. In this model, concentration polarization is incorporated for the solution flow through a semi-permeable membrane (i.e., permeable for solvent but not for solute) in a circular pipe. The effect of the concentration polarization on the flow field in a circular pipe under a viscous-dominant condition (i.e., at a low Reynolds number) is discussed by comparing the CPM with the numerical simulation results and infinitesimal Péclet number model (IPM) for the membrane permeability, strength of the osmotic pressure, and Péclet number. The CPM and IPM are confirmed to be a reasonable extension of the model for a pure fluid, which was proposed previously. The application range of the IPM is narrow because the advection of the solute concentration is not considered, whereas the CPM demonstrates superior applicability in a wide range of parameters, including the permeability coefficient, strength of the osmotic pressure, and Péclet number. This suggests the necessity for considering concentration polarization. Although the mathematical expression of the CPM is more complex than that of the IPM, the CPM exhibits a potential to accurately predict the permeability parameters for a condition in which a large permeate flux and osmotic pressure occur.

The Effect of Permeability Variations on the Flow in a Heterogeneous Porous Channel Subject to Rotation

1999 ◽  
Vol 121 (3) ◽  
pp. 568-573 ◽  
Author(s):  
Peter Vadasz ◽  
Mark A. Havstad
Keyword(s):  
Fluid Flow ◽  
Cross Section ◽  
Three Dimensional ◽  
Axial Flow ◽  
Vertical Gradient ◽  
Porous Channel ◽  
Governing Equations ◽  
Permeability Function ◽  
Vortex Solutions ◽  
The Impact

A significant effect of permeability variations on the three-dimensional fluid flow in a heterogeneous porous channel subject to rotation is presented. The results of a numerical solution to the governing equations confirm for the more general case the conclusions from earlier analytical investigations, which suggest that permeability functions be classified corresponding to whether their variation is monotonic or not, and to whether their vertical gradient is positive or not. Unicellular and multiple vortex solutions are obtained for the secondary flow in the plane perpendicular to the imposed axial flow, while their direction is dictated by the corresponding class of permeability function as applicable. The impact of rotation on the imposed axial flow is shown to be significant as well, leading to different axial flow fields depending again on the class of permeability function used. In particular, the rotation impacts significantly in creating axial flow deficiencies in some regions on the cross section.

Impact of Reservoir Permeability on Flowing Sandface Temperatures: Dimensionless Analysis

SPE Journal ◽  
2013 ◽  
Vol 18 (04) ◽  
pp. 685-694 ◽  
Author(s):  
J.F.. F. App ◽  
K.. Yoshioka
Keyword(s):  
Heat Transfer ◽  
Temperature Change ◽  
Expansion Coefficient ◽  
Peclet Number ◽  
Maximum Temperature ◽  
Péclet Number ◽  
Dimensionless Analysis ◽  
Reservoir Permeability ◽  
Layer Flow ◽  
The Impact

Summary Layer flow contributions are increasingly being quantified through the analysis of measured sandface flowing temperatures. It is commonly known that the maximum temperature change is affected by the magnitude of the drawdown and the Joule-Thomson expansion coefficient of the fluid. Another parameter that strongly impacts layer sandface flowing temperatures is the layer permeability. Aside from determining the drawdown, the layer permeability also affects the ratio of heat transfer by convection to conduction within a reservoir. The impact of permeability can be represented by the Péclet number, which is a dimensionless quantity representing the ratio of heat transfer by convection to conduction. The Péclet number is directly proportional to reservoir permeability. Through dimensionless analysis, it will be shown that for a given drawdown (based on a dimensionless Joule-Thomson expansion coefficient JTD) the temperature change diminishes at low Péclet numbers and increases at high Péclet numbers. This implies that for low-permeability reservoirs such as shale gas or tight oil, the temperature changes will be minimal (less than 0.1ºF) despite the large drawdowns in many instances. Dimensionless analysis is performed for both steady-state and transient thermal models. Results from multilayer transient simulations illustrate the ability to identify contrasting permeability layers on the basis of the Péclet number effect.

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