Analysis of Viscoelastic Flows Through Converging-Diverging Channels

2004 ◽  
Author(s):  
Mauricio Lane ◽  
Moˆnica F. Naccache ◽  
Paulo R. Souza Mendes
Keyword(s):  
Pressure Drop ◽  
Newtonian Fluid ◽  
Geometric Mean ◽  
Viscoelastic Fluids ◽  
Momentum Conservation ◽  
Viscoelastic Flows ◽  
Generalized Newtonian Fluid ◽  
Fluid Behavior ◽  
Fluent Software ◽  
Flow Through

In this work, the flow of viscoelastic fluids through axisimmetric converging-diverging channels is analyzed. The solution of mass and momentum conservation equations is obtained numerically via finite volume technique using the Fluent software. The Generalized Newtonian Fluid constitutive equation was used to model the non-Newtonian fluid behavior, using the Shunk-Scriven model for the viscosity, where a weighted geometric mean between shear and extensional viscosities is assumed. The results of pressure drop are compared to the ones predicted by a previously proposed simplified relation (Souza Mendes and Naccache, 2002) between pressure drop and flow rate, for viscoelastic fluids flow through porous media, in order to analyze its performance.

scholarly journals UNSTEADY TWO-LAYERED BLOOD FLOW THROUGH A -SHAPED STENOSED ARTERY USING THE GENERALIZED OLDROYD-B FLUID MODEL

2016 ◽  
Vol 58 (1) ◽  
pp. 96-118 ◽  
Author(s):  
AKBAR ZAMAN ◽  
NASIR ALI ◽  
O. ANWAR BEG ◽  
M. SAJID
Keyword(s):  
Blood Flow ◽  
Differential Equations ◽  
Newtonian Fluid ◽  
Numerical Solutions ◽  
Fluid Model ◽  
Initial Boundary ◽  
Momentum Conservation ◽  
Rheological Parameters ◽  
Stenosed Artery ◽  
Flow Through

A theoretical study of an unsteady two-layered blood flow through a stenosed artery is presented in this article. The geometry of a rigid stenosed artery is assumed to be$w$-shaped. The flow regime is assumed to be laminar, unsteady and uni-directional. The characteristics of blood are modelled by the generalized Oldroyd-B non-Newtonian fluid model in the core region and a Newtonian fluid model in the periphery region. The governing partial differential equations are derived for each region by using mass and momentum conservation equations. In order to facilitate numerical solutions, the derived differential equations are nondimensionalized. A well-tested explicit finite-difference method (FDM) which is forward in time and central in space is employed for the solution of a nonlinear initial boundary value problem corresponding to each region. Validation of the FDM computations is achieved with a variational finite element method algorithm. The influences of the emerging geometric and rheological parameters on axial velocity, resistance impedance and wall shear stress are displayed graphically. The instantaneous patterns of streamlines are also presented to illustrate the global behaviour of the blood flow. The simulations are relevant to haemodynamics of small blood vessels and capillary transport, wherein rheological effects are dominant.

Approximate Calculation of Pressure Drop in Laminar Flow of Generalized Newtonian Fluid Through Channels with Insert

1995 ◽  
Vol 60 (9) ◽  
pp. 1476-1491
Author(s):  
Václav Dolejš ◽  
Petr Doleček ◽  
Ivan Machač ◽  
Bedřich Šiška
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Numerical Solution ◽  
Newtonian Fluid ◽  
Calculation Method ◽  
Approximate Calculation ◽  
Creeping Flow ◽  
Experimental Results ◽  
Generalized Newtonian Fluid

An equation of Rabinowitsch-Mooney type has been suggested for approximate calculation of pressure drop in flow of generalized Newtonian fluid through channels with insert both in the region of creeping flow and at higher values of the Reynolds number, and this calculation method has been verified for four types of insert using own numerical solution and experimental results as well as literature data.

scholarly journals CFD Analysis of Non-Newtonian Pseudo Plastic Liquid Flow through Bends

2017 ◽  
Vol 61 (3) ◽  
pp. 184 ◽  
Author(s):  
Suman Debnath ◽  
Tarun Kanti Bandyopadhyay ◽  
Apu Kumar Saha
Keyword(s):  
Pressure Drop ◽  
Liquid Flow ◽  
Static Pressure ◽  
Methyl Cellulose ◽  
Bend Angle ◽  
Frictional Pressure Drop ◽  
Fluid Behavior ◽  
Diameter Pipe ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through

Non-Newtonian pseudo plastic liquid flow through different types of 0.0127 m diameter pipe bends as well as straight pipe have been investigated experimentally to evaluate frictional pressure drop across the bends in laminar and water flow in turbulent condition. We have studied here the effect of flow rate, bend angle, fluid behavior on static pressure and pressure drop. A Computational Fluid Dynamics (CFD) based software is used to predict the static pressure, pressure drop, shear stress, shear strain, flow structure, friction factor, loss co- efficient inside the bends for Sodium Carboxy Methyl Cellulose (SCMC) solution as a non-Newtonian pseudo plastic fluids and water as a Newtonian fluid. Laminar Non-Newtonian pseudo plastic Power law model is used for SCMC solution to numerically solve the continuity and the momentum equations. The experimental data are compared with the CFD generated data and is well matched. The software predicted data may be used to solve any industrial problem and also to design various equipment.

scholarly journals EXPERIMENTAL STUDY OF THE FLOW DYNAMICS OF COMPLEX VISCOELASTIC FLUID THROUGH HYPERBOLIC CONTRACTION/EXPANSION

2020 ◽  
pp. 76-94
Author(s):  
Muñoz Garduño Kevin David ◽  
Pérez Camacho Mariano
Keyword(s):  
Pressure Drop ◽  
Shear Flow ◽  
Extensional Flow ◽  
Viscoelastic Fluids ◽  
Excess Pressure ◽  
Flow Dynamics ◽  
Shear Type ◽  
Flow Through ◽  
Expansion System ◽  
Hyperbolic Contraction

The main objetive of this work was to experimentally study the Flow dynamics of viscoelastic fluids (Boger fluid and Hase) when they flow through a contraction/expansion system defined by a hyperbolic tube, therefore through equations analogous to the Hagen-Poiseuille equation, the pressure drop associated with the viscous interaction was quantified, and subsequently the excess pressure drop (EPD), a parameter associated with the elasticity of viscoelastic fluids, conducting comparative studies with respect to a Newtonian reference for the same shear viscosity value, which allowed observing shear speed intervals where three predominant zones were observed. The first of them of shear type coinciding with the trajectories of the Newtonian fluid of identical viscosity value, the second zone was attributed to the elastic manifestation of the fluids due to the preferential development of the extensional flow that is in constant competition with the shear flow within of the same geometry. The third zone was attributed to a predominance of the shear flow over the extensional one, because of to the fact that the hyperbolic geometry favors the development of this type of flow at high values of shear rate KEYWORDS: Excess pressure drop; Extensional flow; Hyperbolic contractions

Numerical Modeling of Non-Newtonian Fluid Flow in a Porous Medium Using a Three-Dimensional Periodic Array

1998 ◽  
Vol 120 (1) ◽  
pp. 131-135 ◽  
Author(s):  
Masahiko Inoue ◽  
Akira Nakayama
Keyword(s):  
Porous Medium ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Pressure Gradient ◽  
Newtonian Fluid ◽  
Three Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Inertia Effects ◽  
Flow Through

Three-dimensional numerical experiments have been conducted to investigate the viscous and porous inertia effects on the pressure drop in a non-Newtonian fluid flow through a porous medium. A collection of cubes placed in a region of infinite extent has been proposed as a three-dimensional model of microscopic porous structure. A full set of three-dimensional momentum equations is treated along with the continuity equation at a pore scale, so as to simulate a flow through an infinite number of obstacles arranged in a regular pattern. The microscopic numerical results, thus obtained, are processed to extract the macroscopic relationship between the pressure gradient-mass flow rate. The modified permeability determined by reading the intercept value in the plot showing the dimensionless pressure gradient versus Reynolds number closely follows Christopher and Middleman’s formula based on a hydraulic radius concept. Upon comparing the results based on the two- and three-dimensional models, it has been found that only the three-dimensional model can capture the porous inertia effects on the pressure drop, correctly. The resulting expression for the porous inertia possesses the same functional form as Ergun’s, but its level is found to be only one third of Ergun’s.

Generalized Newtonian fluid flow through fibrous porous media

2016 ◽  
Author(s):  
Magdalena Mierzwiczak ◽  
Jan Adam Kołodziej ◽  
Jakub Krzysztof Grabski
Keyword(s):  
Porous Media ◽  
Fluid Flow ◽  
Newtonian Fluid ◽  
Generalized Newtonian Fluid ◽  
Fibrous Porous Media ◽  
Flow Through

scholarly journals Rapid Numerical Estimation of Pressure Drop in Hot Runner System

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 207
Author(s):  
Jae Sung Jung ◽  
Sun Kyoung Kim
Keyword(s):  
Pressure Drop ◽  
Injection Molding ◽  
Steady Flow ◽  
Design Process ◽  
Newtonian Fluid ◽  
Numerical Estimation ◽  
Generalized Newtonian Fluid ◽  
Computer Tool ◽  
Pressure Drops ◽  
Runner Design

To determine dimensions in the hot runner systems, given a material, it is necessary to predict the pressure drop according to them. Although modern injection molding simulators are able to evaluate such pressure drops, they are expensive and demanding to be employed as a design utility. This work develops a computer tool that can calculate a pressure drop from the sprue to the gate assuming a steady flow of a generalized Newtonian fluid. For a four drop hot runner system, the accuracy has been verified by comparing the obtained results with those by a commercial simulator. This paper presents how to utilize the proposed method in the hot runner design process.

scholarly journals The Effect of Boundary Slip on the Transient Pulsatile Flow of a Modified Second-Grade Fluid

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
N. Khajohnsaksumeth ◽  
B. Wiwatanapataphee ◽  
Y. H. Wu
Keyword(s):  
Newtonian Fluid ◽  
Numerical Solutions ◽  
Fluid Model ◽  
Second Grade ◽  
Second Grade Fluid ◽  
Boundary Slip ◽  
Fluid Behavior ◽  
Grade Fluid ◽  
Complete Set ◽  
Flow Through

We investigate the effect of boundary slip on the transient pulsatile fluid flow through a vessel with body acceleration. The Fahraeus-Lindqvist effect, expressing the fluid behavior near the wall by the Newtonian fluid while in the core by a non-Newtonian fluid, is also taken into account. To describe the non-Newtonian behavior, we use the modified second-grade fluid model in which the viscosity and the normal stresses are represented in terms of the shear rate. The complete set of equations are then established and formulated in a dimensionless form. For a special case of the material parameter, we derive an analytical solution for the problem, while for the general case, we solve the problem numerically. Our subsequent analytical and numerical results show that the slip parameter has a very significant influence on the velocity profile and also on the convergence rate of the numerical solutions.

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