Topic
Herschel–Bulkley fluid
About: Herschel–Bulkley fluid is a research topic. Over the lifetime, 1946 publications have been published within this topic receiving 49318 citations.
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01 Jan 2011TL;DR: In this article, the authors present a method to calculate the linearized rotor-dynamic coefficients for a liquid seal with large aspect ratio (balance drum) subjected to incompressible turbulent flow by means of a three dimensional CFD analysis to calculate fluid-induced forces acting on the rotor.
Abstract: The instability due to fluid flow in seals is a known phenomenon that can occur in pumps and compressors as well as in steam turbines. Traditional annular seal models are based on bulk flow theory. While these methods are computationally efficient and can predict dynamic properties fairly well for short seals, they lack accuracy in cases of seals with complex geometry or with large aspect ratios (above 1.0). Unlike the bulk flow models, computational fluid dynamics (CFD) makes no simplifying assumption on the seal geometry, shear stress at the wall, relationship between wall shear stress and mean fluid velocity, or characterization of interfaces between control volumes through empirical friction factors. This paper presents a method to calculate the linearized rotor-dynamic coefficients for a liquid seal with large aspect ratio (balance drum) subjected to incompressible turbulent flow by means of a three dimensional CFD analysis to calculate the fluid-induced forces acting on the rotor. The Reynolds-averaged Navier-Stokes equations for fluid flow are solved by dividing the volume of fluid into a discrete number of points at which unknown variables are computed. As a result, all the details of the flow field, including the fluid forces with potential destabilizing effects, are calculated. A 2nd order curve fit is then used to express the fluid-induced forces in terms of equivalent linearized stiffness, damping, and fluid inertia coefficients.Copyright © 2011 by ASME
2 citations
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TL;DR: In this article, the effects of slip velocity and aligned Magneto hydro-dynamic on Jeffrey fluid which passing across a stretching sheet with Newtonian heating boundary condition are investigated, and the results from this project will enhance the knowledge in non-Newtonian fluid problem via mathematical approach.
Abstract: Objectives: Effects of slip velocity and aligned Magneto hydro-dynamic on Jeffrey fluid which passing across a stretching sheet with Newtonian heating boundary condition are investigated. Methods/Statistical Analysis: Governing partial differential equations are first transformed into ordinary differential equation by applying the similarity transformations before undergo computation process using y bvp4c in MATLAB. Findings: For validation purposes, the present results are comparing with the outcome from previous publications for the case Constant Wall Temperature (CWT) and it shows a very strong agreement on the values of −θ′(0) . From the study, the increasing on the values of magnetic parameter, M drop the fluid velocity for the range value of boundary layer thickness 0 3.5 , the value of fluid velocity is increasing on the larger magnetic parameter. However, the distribution on temperature of fluid shows an opposite trend as compare with fluid velocity. On the range of 0 2.5 it evidently reduce the velocity of fluid. The fluid temperature is high at smaller values of Deborah number. The distribution on velocity and temperature of fluid presented in this article are strictly asymptotically fulfilling the boundary conditions which then contribute to the adequate of the present results. Application/Improvements: The results from this project will enhance the knowledge in non-Newtonian fluid problem via mathematical approach.
2 citations
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TL;DR: A phenomenological model for dispersed systems which exhibit complex rheological behaviour such as shear and time-dependent viscosity, yield stress, and elasticity is proposed in this paper.
Abstract: A phenomenological model for dispersed systems which exhibit complex rheological behaviour such as shear and time-dependent viscosity, yield stress, and elasticity is proposed. The model extends the Quemeda model to describe the viscosity function with a structural parameter λ which varies according to different kinetic orders of particle aggregation and segregation. The transient stress response is obtained by solving an instantaneous Maxwell model with an assumed shear modulus functionG of the same form as the viscosity function η. Accuracy of the proposed model is verified experimentally with the results obtained for two oil (creosote)/water emulsions. The model that gives the best fit of experimental data appears to be the one with kinetic ordersn=m=2.
2 citations
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TL;DR: In this article, the authors investigated the flow of a Herschel-Bulkley fluid in an annular cylinder without making prior assumptions on the form of velocity profile within the boundary layer region and determined the velocity distribution by cross sectional integration of the momentum differential equation for a given distance z from the channel entrance.
Abstract: The entrance region
flow of a Herschel-Bulkley fluid in an annular cylinder has been investigated
numerically without making prior assumptions on the form of velocity profile
within the boundary layer region. This velocity distribution is determined as
part of the procedure by cross sectional integration of the momentum
differential equation for a given distance z from the channel entrance. Using
the macroscopic mass and momentum balance equation, the entrance length at each
cross section of the entrance region of the annuli and pressure distribution
have been calculated for specific values of Herschel-Bulkley number and various
values of aspect ratio and flow behavior index. The effects of non-Newtonian
characteristics and channel width on the velocity profile, pressure
distribution and the entrance length have been discussed.
2 citations
01 Jan 2014
TL;DR: In this paper, the rimming flow of a thin polymeric film inside a rotating horizontal cylinder is studied theoretically and the non-Newtonian fluid viscosity is described by the Generalized Newtonian Fluid (GNF) constitutive model.
Abstract: The rimming flow of a thin polymeric film inside a rotating horizontal cylinder is studied theoretically. The nonNewtonian fluid viscosity is described by the Generalized Newtonian Fluid (GNF) constitutive model. With linear stability analysis, it is found that, analogously to Newtonian fluids, rimming flow of viscous non-Newtonian fluids is neutrally stable.
2 citations