ENCIT2012-358 SOME REMARKS ABOUT THE USE OF GORDON-SCHOWALTER TIME DERIVATIVE IN RATE-TYPE VISCOELASTIC CONTITUTIVE EQUATIONS - PDF
Heraldo Silva da Costa Mattos, UFF, Brazil
Abstract: The present paper is concerned with the analysis of the thermodynamic consistency of rate-type constitutive equations for viscoelastic fluids using the Gordon-Schowalter objective time derivative. The choice of the objective time derivative is important not only to assure a mathematically correct and physically realistic description of the viscoelastic behaviour, but also to perform a thermodynamically consistent modelling. It is shown that, for some very popular constitutive equations that adopt the Gordon-Schowalter objective derivative, it is impossible to automatically assure that the second law of thermodynamics is satisfied in any process.
Keywords:viscoelastic fluid behaviour; Gordon-Schowalter objective derivative; Oldroyd type fluids; second law of thermodynamics.
Presentation Schedule: Monday, 15:20-15:40. Session: FMR2-1. Presenter: Heraldo da Costa Mattos.
ENCIT2012-348 NUMERICAL SIMULATION OF POWER-LAW FLUID FLOWS IN A POROUS CHANNEL - PDF
Jesús Alfonso Puente Angulo, Maria Laura Martins-Costa, Heraldo Silva da Costa Mattos, UFF, Brazil
Abstract: A porous channel limited by two impermeable flat plates is modeled by employing a mixture theory that treats fluid saturated porous media by considering the fluid and the porous matrix as superimposed continuous constituents of a binary mixture - each of them occupying its whole volume. The flow of a power-law fluid through a porous channel, for both shear-thinning and shear-thickening responses is simulated using a Runge-Kutta method coupled with a shooting strategy. Despite the strong nonlinearity of the problem, the methodology provides stable and accurate results.
Keywords:mixture theory; power-law fluid; fluid saturated porous medium.
Presentation Schedule: Thursday, 12:00-12:20. Session: FMR2-3. Presenter: Jesús Alfonso Puente Angulo.
ENCIT2012-095 FLOW OF THIXOTROPIC FLUID THROUGH AXISYMMETRIC EXPANSIONS-CONTRACTIONS. - PDF
Edgar Cando, Priscilla Ribeiro Varges, Paulo Roberto de Souza Mendes, PUC-Rio, Brazil
Abstract: The behavior of thixotropics fluids through axisymmetrics expansions-contractions is studied in this research. The aim is to visualize the "shear banding" in the flow of a thixotropic fluid, which is the interface between a flowing fluid and a non-flowing fluid. This research uses an experimental appraoch to visualize the "shear banding" within the fluid. The variables used in the experimental procedure were: steady flow rate time, flow rate and geometric characteristics. A dispersion of laponite RD was utilized as the experimental fluid due to its thixotropic and transparent properties. The fluid flow curve, strain sweep and frequency sweep were used to obtain the rheology characterization. The rheology characterization showed lack of repeatability due to several factors, such as: aging, type of rheometers, geometry used in the rheometers and lack of sample pre shearing. Finally, the results showed that laponite RD is a thixotropic fluid, more elastic than viscous in the viscoelastic region and that the flow through the axisymmetrics expansion-contraction device showed three types of behaviors constant flow area, variable flow area with an expansion in the middle zone and variable flow area with layers of different velocities.
Keywords:Thixotropy; expansion-contraction; Yield stress; Visualization.
Presentation Schedule: NO PRESENTATION.
ENCIT2012-166 SIMPLIFIED MATHEMATICAL MODEL FOR MIGRATION OF GAS BUBBLES IN VISCOPLASTIC FLUIDS - PDF
William Fernando Lopez, Aline Abdu, Monica Feijo Naccache, PUC-Rio, Brazil
Abstract: In this work, a study of the rising movement of single gas bubble in vicoplastic fluid is performed, using the Ansley and Smith equations. The solution is obtained numerically and the numerical results are compared with experimental results from the literature. The calculations are performed for spherical bubbles, low Reynolds number (<1), constant temperature, and neglecting wall effects. The effects of bubble mass and surface tension are analyzed. In addition, a bi-dimensional numerical study is performed, also for a single bubble motion. The numerical solution of the governing conservation equations of mass and momentum is obtained with the FLUENT software, using the finite volume technique and the volume of fluid (VOF) method. The results obtained with the simplified model are in a fair agreement with the literature. Moreover, comparisons will be evaluated between the numerical 2-D model and the simplified one.
Keywords:gas; Bubble; Viscoplastic; Fluid.
Presentation Schedule: Thursday, 09:40-10:00. Session: FMR2-2. Presenter: William Fernando Lopez.
ENCIT2012-171 EXTENSIONAL RHEOLOGY OF FIBER REINFORCED FLUIDS - PDF
Juliana de Paiva Correa, Isabela Fernandes Soares, Aline Abdu, Monica Feijo Naccache, PUC-Rio, Brazil
Abstract: Understanding the benefits of fiber reinforcement in the properties of the polymers composites, shows that it is possible to improve the material characteristic performance and reduce costs. In many applications, fibers are added to improve the mechanical properties of the original material, and hence increase their competitiveness with metallic materials. The rheological properties of the polymer composites have important effects on the mechanical properties of the final products. On the other hand, characterization of composite materials is a difficult task, due to the several variables involved. In the present work, a rheological investigation of suspensions containing Wollastonite fibers and glass fibers is performed using the Paar Physica rotational rheometer and the CaBER extensional rheometer. The influence of fiber concentration and the effect of temperature on rheology in a Newtonian polybutene/kerosene matrix and in a viscoelastic fluid matrix have been analyzed. The results obtained show that both types of suspensions exhibit similar viscosities when subjected to shear flows. However, when exposed to extensional flows, an increase of the filament break up time is observed for the Wollastonite fibers, due to an increase of the extensional viscosity.
Keywords:rheology; extensional viscosity; fiber reinforcement.
Presentation Schedule: Thursday, 11:40-12:00. Session: FMR2-3. Presenter: Juliana Correa.
ENCIT2012-206 SAFFMAN-TAYLOR INSTABILITY IN A LIQUID-LIQUID DISPLACEMENT FLOW INCLUDING NON-NEWTONIAN EFFECTS - PDF
Eduardo de Montenegro Trindade, Patrícia Emídio Azevedo, Priscilla Ribeiro Varges, Paulo Roberto de Souza Mendes, PUC-Rio, Brazil
Abstract: Viscous fingering in non-Newtonian fluids in a rectangular Hele-Shaw cell was investigated numerically and experimentally. Visualization experiments were performed using Xanthan Gum and a Newtonian mineral oil. The channel, made of transparent glass, is 150mm wide and 700mm long, and the gap between the glass plates is 0.70mm. A digital camera is used to capture images of the interface between the fluids during the flow. The interface shape is given for different values of flow rate and viscosity ratio. The main parameters that govern this flow are the viscosity ratio, the rhe-ological capillary number, and the (dimensionless) flow rate. The Reynolds number is kept low for all cases investigated, to ensure negligible inertia.
Keywords:Hele-Shaw cell; Invasion and drilling fluid; Viscous fingering.
Presentation Schedule: Thursday, 10:20-10:40. Session: FMR2-2. Presenter: Eduardo de Montenegro Trindade.
ENCIT2012-210 TURBULENT VISCOPLASTIC FLOWS INSIDE A LID-DRIVEN CAVITY - PDF
Paulo Arthur Beck, Horácio Antonio Vielmo, Sérgio Luiz Frey, UFRGS, Brazil
Abstract: This paper presents the results obtained by numerically simulating lid-driven flows of a viscoplastic liquid inside a 3D cavity. The flows are formulated by the principles of mass and momentum balances and the V2F k-epsilon turbulence model equations. The liquid's dynamic viscosity is given by the SMD viscosity function such that the shear stress field is regularized using only rheological properties. The Finite Volume Method is applied to linearize the system of transport equations characterizing the flows. The problem domain is discretized by hexahedral volumes and the resulting meshes are verified following the generalized Richardson's Extrapolation Method. The effects of inertia and turbulence on the flow's morphology and yield surfaces are presented for a fixed set of governing parameters and varying power-law Reynolds numbers.
Keywords:Viscoplasticity; SMD Viscosity Function; Turbulence; V2F k-epsilon Model.
Presentation Schedule: Thursday, 09:20-09:40. Session: FMR2-2. Presenter: Paulo Arthur Beck.
ENCIT2012-102 APPARENT WALL SLIP IN FLOWS OF VISCOPLASTIC FLUID THROUGH A PARALLEL-PLATE CHANNEL - PDF
Alexandra A. Alicke, Ricardo T. Leite, Paulo Roberto de Souza Mendes, Flávio Henrique Marchesini de Oliveira, PUC-Rio, Brazil
Abstract: The present research consists of an experimental study of the behaviour of aqueous solutions of carbopol and the phenomenon of wall slip during during an internal flow through a parallel-plate channel. The channel is 100mm wide, 150mm long, and the gap between plates is 1mm. We use plates different materials and roughness. The Reynolds number is low for all cases investigated to ensure negligible development length. In the experiments, the pressure drop is measured for different flow rate values, and the results are presented in the form of curves of dimensionless average velocity versus dimensionless wall shear stress. We also performed experiments with glycerol, and the results agreed with the analytical solution available in the literature. Moreover, this agreement ensures the absence of wall slip for this Newtonian case.
Keywords:Wall slip; Drag reduction; Viscoplastic fluids; Wettability.
Presentation Schedule: Thursday, 09:00-09:20. Session: FMR2-2. Presenter: Ricardo T. Leite.
ENCIT2012-116 RHEOLOGICAL BEHAVIOR OF SOYBEAN BIODIESEL AT LOW TEMPERATURES - PDF
Alexandra A. Alicke, Bruna C. Leopércio, Paulo Roberto de Souza Mendes, Flávio Henrique Marchesini de Oliveira, PUC-Rio, Brazil
Abstract: Abstract. The importance of biodiesel fuels as a renewable energy resource has been growing fast over the last years due to its many advantages over petroleum fuels, such as low toxicity, low CO2 emission, and higher lubricity and biodegradability. However, its main disadvantage is related to the poor cold flow properties. At low temperatures, wax crystallizes and gives rise to a gelation process that may lead to plugging of filters and lines. Although this consists a major problem for the use of biodiesel as fuels, little has been done in order to investigate the rheological behavior of these materials at low temperatures. In this paper, the rheological characterization of soybean biodiesel is performed under the guidelines of a recently pro- posed protocol for waxy crude oils (Marchesini et al., 2012), which possesses a similar behavior at low temperatures. We present a set of preliminary results, including thermal cycle, constant shear stress and oscillatory tests.
Keywords:rheology; biodiesel; low temperature; flow properties.
Presentation Schedule: Monday, 16:20-16:40. Session: FMR2-1. Presenter: Bruna C. Leopércio.
ENCIT2012-150 MOTION OF GAS BUBBLES IN VISCOPLASTIC FLUIDS - PDF
Alexandra A. Alicke, Fernando V. da Senhora, Marcos Cid, Paulo Roberto de Souza Mendes, PUC-Rio, Brazil
Abstract: One of the most troublesome problems of the petroleum industry is annular gas migration. Gas invasion occurs when pressure is lower in the annulus than at the formation face during drilling or well completion procedures. The gas may migrate to a lower pressure zone, or possibly to the surface The objective of our research is to determine stagnant conditions, terminal velocity and formation parameters for gas bubbles occurring in viscoplastic fluids, in order to establish under which conditions gas migration might occur. Our experimental set-up consists of a reservoir, filled with a viscoplastic fluid and connected to a syringe for injection of gas bubbles. The bubble velocity is measured both experimentally, using a chronometer, and through sequential pictures. For this matter we use Carbopol dispersions to simulate the properties of cement slurries. Glycerol was also used to compare the results obtained in our experiments to those available in the literature for Newtonian fluids. Laser visualization of the flow around the bubbles was also carried out.
Keywords:gas migration; bubble motion; viscoplastic fluids; rheology.
Presentation Schedule: Thursday, 11:00-11:20. Session: FMR2-3. Presenter: Fernando V. da Senhora.
ENCIT2012-170 NUMERICAL AND EXPERIMENTAL STUDY OF LAMINAR FLUIDS DISPLACEMENT - PDF
Bruno da Silva Fonseca, Marisa Bazzi, Aline Abdu, Flávio Henrique Marchesini de Oliveira, Monica Feijo Naccache, PUC-Rio, Brazil
Abstract: The cement operation of oil and gas wells is extremely important, the successful of this operation guarantee the lifetime of the wells. The adequate operation occurs when the cement slurry distribution on wells wall is homogeneous. For this purpose, the complete displacement of the drilling mud inside annuli space by the cement slurry, is necessary. The process fluids may have a non-Newtonian behavior. In this work, an experimental and numerical study of the fluid displacement of non-Newtonian fluids through annuli concentric geometry are compared. The numerical solution of the governing conservation equations of mass and momentum is obtained with the FLUENT software, using the finite volume technique and the volume of fluid (VOF) method. The non-Newtonian fluid behavior is modeled using the $\backslash$textit{Herschel-Bulkley} model. The cementing process efficiency is evaluated using the density ratio value of the fluids in the annuli outlet. The experimental and numerical results shows good agreement.
Keywords:fluid displacement; annular flow; rheology.
Presentation Schedule: Thursday, 12:20-12:40. Session: FMR2-3. Presenter: Bruno Fonseca.
ENCIT2012-187 NUMERICAL SIMULATIONS OF AN ALTERNATIVE ELASTO- VISCOPLASTIC MODEL - PDF
Daniel Dall Onder dos Santos, Sérgio Luiz Frey, UFRGS, Brazil
Monica Feijo Naccache, Paulo Roberto de Souza Mendes, PUC-Rio, Brazil
Abstract: The main goal of this article is to perform stabilized finite element approximations for inertialess flows of an alternative elasto-viscoplastic model, based on the thixotropic model proposed by de Souza Mendes (2009). This model is approximated by a multi-field Galerkin least squares method in extra-stress, pressure and velocity. This methodology does not need to satisfy the compatibility conditions arisen from finite element sub-spaces for extra-stress-velocity and pressure-velocity. By adding to the classical Galerkin formulation mesh-dependent terms, which are functions of the residuals of the flow governing equations, the stability is obtained without upsetting the classical method consistency. Numerical simulations of the flow over a planar expansion-contraction are carried out. To evaluate the influence of the governing parameters, the yield stress limit (using for this the flow intensity U*) is varied from 7.5x10$^{-3}$ to 1.5; the microstructure shear modulus from 1.0 to 666.67, the power law index from 0.2 to 0.65 and the jump number from 5x10$^2$ to 5x10$^4$.
Keywords:elasto-viscoplasticity; structured fluid; regularized viscoplastic models; multi-field Galerkin least-squares method.
Presentation Schedule: Thursday, 11:20-11:40. Session: FMR2-3. Presenter: Daniel Dall Onder dos Santos.
ENCIT2012-172 A NUMERICAL INVESTIGATION OF THE THIXOTROPIC EFFECTS IN A STRUCTURED FLUID FLOW AROUND A CYLINDER CONFINED BETWEEN TWO PARALLEL PLATES - PDF
Cleiton Fonseca, Sérgio Luiz Frey, UFRGS, Brazil
Monica Feijo Naccache, Paulo Roberto de Souza Mendes, PUC-Rio, Brazil
Roney Leon Thompson, UFF, Brazil
Abstract: Many materials with industrial applications exhibit a thixotropic behavior. Thixotropic fluid has as main feature the breaking of the structure by applying a shear and a restructuring with the removal of this stress. This process is reversible and occurs isothermally. This article aims to study the behavior of these materials, using a model recently proposed by de Souza Mendes, 2009. The equations used in this model is solved by a stabilized finite element method (GLS method). A sensitivity analysis is presented to a creeping flow around a cylinder in a confined planar channel, where the parameters relevant to the model is scanned in order to study their influences.
Keywords:Thixotropy; structured fluids; viscoplastic fluids; complex flows.
Presentation Schedule: Thursday, 10:00-10:20. Session: FMR2-2. Presenter: Mônica Nacacche.
ENCIT2012-189 INERTIA FLOW OF VISCOPLASTIC FLUIDS APPROXIMATED BY A MULTI-FIELD STABILIZED METHOD - PDF
Lober Hermany, Daniel Dall Onder dos Santos, Sérgio Luiz Frey, UFRGS, Brazil
Monica Feijo Naccache, Paulo Roberto de Souza Mendes, PUC-Rio, Brazil
Abstract: The effect of inertia in the flow of viscoplastic fluids through an expansion followed by a contraction is analyzed. The mechanical behavior is modeled by the Generalized Newtonian Fluid constitutive equation, with the viscosity function given by the SMD equation (de Souza Mendes and Dutra, 2004). The conservation equations of mass and momentum, together with the constitutive equation are approximated by a Galerkin least-squares (GLS) formulation in terms of pressure and velocity. A sensitivity analysis is performed, aiming at investigating the influence of inertia and viscous forces on the fluid dynamics. The topology of yield surfaces is obtained, and proved to be strongly related to inertia and yield stress amounts considered in the flow. Moreover, the results are compared to other results from the literature, which consider fluid elasticity. It is observed that inertia and elasticity effects lead to different flow patterns.
Keywords:SMD model; Galerkin Least-Squares method; shear-thinning viscoplastic flow; viscoplastic inertial flows.
Presentation Schedule: Monday, 15:40-16:00. Session: FMR2-1. Presenter: Sérgio Frey.
ENCIT2012-310 FINITE ELEMENT SIMULATIONS OF ELASTO-VISCOPLASTIC STEADY FLOWS WITHIN A LID-DRIVEN CAVITY - PDF
Renato da Rosa Martins, Giovanni Minervino Furtado, Daniel Dall Onder dos Santos, Sérgio Luiz Frey, UFRGS, Brazil
Monica Feijo Naccache, Paulo Roberto de Souza Mendes, PUC-Rio, Brazil
Abstract: The current article aims to perform stabilized finite element approximations for inertialess flows of elasto-viscoplastic fluids. The numerical method employed to approximate the mechanical model equations is the Galerkin least-squares method, in therms of the extra-stress, pressure and velocity. This method is more stable than the classical Galerkin method, what is achieved by the addition of mesh-dependent terms, functions of the residuals of the governing equations. The simulations were performed on a lid-driven cavity employing the elasto-viscoplastic model introduced by Nassar et al., 2011. To evaluate the influence of the elasticity, power-law index and jump number, the non-dimensional relaxation time is varied from 0.2 to 2.0, n from 0.4 to 1.0 and J from 500 to 10000.
Keywords:elasto-viscoplasticity; stabilized Galerkin method; lid-driven cavity flow; multi-field approximation.
Presentation Schedule: Monday, 16:00-16:20. Session: FMR2-1. Presenter: Daniel Dall Onder dos Santos.