Analysis Of Flow Behavior Research Articles

SPH-based analysis of the post-failure flow behavior for soft and hard interbedded earth slope

This study proposed a Smoothed Particle Hydrodynamics (SPH) model that could consider two types of soils with different viscosities to reveal the flow mechanism of a soft and hard interbedded earth slope. The flow processes of an actual unstable slope in the Lushan hot spring district and the Saleshan landslide were simulated, and the applicability of proposed SPH model was validated by comparing the flow process and the flow velocity with DEM results and surveyed data. Thereafter, with a conceptual simulating case for the soft and hard interbedded earth slope, materials were divided into two types, and eight groups consisting of 64 cases were analyzed with different viscosities. According to the variation curves of the run-out and the flow velocity with time, the flow behavior is controlled by the properties of both the soft layer and hard layer, and increasing the viscosity of the hard layer can greatly reduce the run-out and the maximum velocity. The result provided a basis for the mitigation of possible layered earth slope disasters in engineering geology.

Investigation of fluid field analysis, characteristics of pressure drop and improvement of heat transfer in three-dimensional circular corrugated pipes

Abstract In this investigation, the computational technique is carried out to study flow behaviour analysis, pressure drop characteristic and enhancement of heat transfer in three-dimensions smooth pipe and circular corrugated tube (circular sectional area rings are inserted around the tube). Various rings are considered as 0.375, 0.5 and 1 mm. Water is chosen as working fluid and at the tube external surface uniform heat flux is applied. Numerical simulation is performed computational fluid dynamics method at range of Reynolds number from 1500 to 24,000. To calculate the process of governing equations and energy analysis equations in numerical calculations the pressure-based solver double precession is used. Numerical simulation outcomes are validated with available experimental results. Also, the results shown a good agreement between them. Result indicated that the dynamic pressure profile and velocity profile in corrugated tube is non-uniform as compared to profile in smooth pipe. This can be explained due to the corrugated rings around the tube can cause more unstable flow closed to tube wall. Results revealed that the high heat transfer enhancement take place under low mass flow is 0.56 litter per min and corrugate ring of 1 mm and it is equal 26.48%, 19.43 and 15.26% for corrugate ring of 1, 0.5 and 0.375 mm respectively.

Analysis of flow behaviour and strain partitioning mechanism of bimetal composite under hot tensile conditions

The flow behaviour and strain partitioning of 2205 duplex ferritic-austenitic stainless steel/AH36 low carbon steel bimetal composite (2205/AH36 BC) were investigated at elevated temperatures in this study. A physically-based constitutive model was established to describe the flow behaviour of bimetal composite based on the stress–strain relationships obtained from hot tensile tests, which were performed on a Gleeble 3500 thermal-mechanical test simulator over the temperature range of 950–1250 °C and strain rate range of 0.01–1 s−1. The stress and strain partitioning of bimetal composite was analysed to develop a mixture law of flow stress under those hot working conditions, due to the different strain contributions of each material on the total flow behaviour of bimetal composite. The developed constitutive model and the mixture law considering strain partitioning were both adopted to predict the stress–strain curves and used in finite element (FE) simulation model to calculate the peak loads of 2205/AH36 BC at 1000 °C. It is found that the softening mechanisms of 2205/AH36 BC changes depending on the externally imposed working temperatures and strain rates. The contribution of AH36 carbon steel layer on total stress is relatively more than that of 2205 stainless steel layer at high temperatures, as a result of the occurrence of stress partitioning. The proposed constitutive model, instead of the mixture law, is recommended to be used in the FE simulation of practical hot working of bimetal composite due to its high accuracy.

Effect of Thermal Radiation on a Three-dimensional Stagnation Point Region in Nanofluid under Microgravity Environment

The unsteady three dimensional boundary layer flow near a stagnation point region is studied numerically under the influence of microgravity environment. The boundary layer plate was embedded by the nanofluid with nanosized copper particles and water as a based fluid together with thermal radiation effect. The problem was mathematically formulated in term of coupled governing equations consisting of continuity, momentum and energy equations derived from the fundamental physical principles with Tiwari and Das nanofluid model. Boundary layer and Boussinesq approximation were then applied to the coupled equations and then reduced into non-dimensional equations to lessen the complexity of the problem using semi-similar transformation technique. Implicit finite different method known as Keller box method was used in this problem. The problem was then analyzed in terms of physical quantities of principal interest known as skin frictions and Nusselt number which explained the flow behavior and heat transfer analysis. From the outcome of the analysis, it was found that the parameter values for curvature ratio lead to the different cases of the stagnation point flow which is either plane stagnation flow or asymmetry stagnation flow. On the other hand, by increasing the nanoparticles volume fraction which is one of the nanofluid parameter may increase the skin frictions on both x- and y- directions. The presence of thermal radiation parameter was found to have increased the rate of change of heat transfer at the boundary layer flow.

NUMERICAL INVESTIGATION OF TANDEM EFFECTS ON BLUFF BODIES AERODYNAMICS

Flow over bluff body is an interesting subject in recent time, which has always attractive the attention of aerodynamic researchers due to their unique flow behavior. Bluff bodies in tandem have a wide range application in engineering, such as in road vehicles (truck-trailer), railway trains, high tower building, industrial chimneys…etc. However, the non-streamed with sharp leading edges bodies exposure to high pressure drag at front face and flow separation from the leading sharp corners. Understanding the flow over these bodies led to optimize the design and control flow field by means of active or passive technique. Therefore, the main aim of the present study is to describe numerically the flow field and shielding effects of various square plates, placed coaxially as front body upstream of the square flat-faced sharp leading-edges with rounded back rear body. Analysis of 3D fluid flow behavior around the rear body alone and for the different geometrical combinations (width and gap ratios) at three Reynolds numbers based on the width of rear body in the range 1-1.8 ×105 were considered. The Computational Fluid Dynamic (CFD) using ANSYS FLUNET (19.1) with K-Ɛ turbulence model are considered for solving the governing equations for tested models. The simulated results of the flow properties such as flow stream velocity components, pressure distribution contours and pressure coefficient (Cp) around the rear body alone and front-rear body combinations, show that the optimum combination occurred at (b1/b2=0.75 and g/b2=0.5) with maximum drag reduction of 48% and 12% for the speeds 15 and 20 m/s, respectively. This reduction is due to the shielding effect of the front body that cause the separation streamlines from the front body reattachment onto or very close to the rear body shoulder. The contours of instantaneous streamline velocity patterns, pressure (Cp) and drag coefficients distributions were performed. The numerical results show a good agreement with the experimental results.

Thermal Radiation Effects on Heat and Mass Transfer of Magnetohydrodynamics Dusty Jeffrey Fluid past an Exponentially Stretching Sheet

The heat and mass transfer of steady magnetohydrodynamics of dusty Jeffrey fluid past an exponentially stretching sheet in the presence of thermal radiation have been investigated. The main purpose of this study is to conduct a detailed analysis of flow behaviour of suspended dust particles in non-Newtonian fluid. The governing equations hav been converted into dimensionless form, and then solved numerically via the Keller-box method. The expression of Sherwood number, Nusselt number and skin friction have been evaluated, and then displayed in tabular forms. Velocity, temperature and concentration profiles are presented graphically. It is observed that large value of dust particles mass concentration parameter has reduced the flow velocity significantly. Increase in radiation parameter enhances the temperature, whereas the increment in Schmidt number parameter reduces the concentration.

Stress analysis of ore particle flow behaviour under the influence of a flexible barrier

Additional stresses caused by a flexible barrier, drawpoints and the self-weight of ore particles were investigated based on a physical experiment of the shrinkage stoping method of synchronous filling, and the flow behaviour of ore particles is described by the component forces. This study shows that when ore particles are drawn from multiple drawpoints under the influence of a flexible barrier, the stress distribution of the ore particles is sinusoidal, with an amplitude that gradually decreases with increasing height. The values of σx and σy gradually decrease with increasing height; the maximum σy values occur at x = 0, the maximum σx values occur at x = ± 10 and the maximum shear stresses occur near the lateral walls. The shape of the draw column is determined by the additional vertical stress, and its contour determines the essential morphology of the drawbody. The surface of the ore particles is smoothed by the additional stress caused by the barrier, and the self-weight of the ore particles is the inherent cause of the additional stress.

Laws and principles governing fluid flow in porous media.

Currently, it is impossible to imagine the petroleum industry without utilising numerical simulation methods for reservoir analysis and production. Investigating the petroleum reservoir performance calls for a comprehensive understanding of the physical processes that govern flow transport in porous media. Irrespective of the goals of the analysis whether pertaining to core investigations, reservoir simulation and planning of enhanced recovery methods, flow processes obey the same physical laws. In this paper, the basic laws and principles describing fluid flow and flow patterns manifesting in subsurface porous media are discussed. Appreciating the applicability and limitations of the physical laws allows us to develop and employ modelling methods for flow behaviour analysis and reservoir performance prediction which is the main goal of petroleum engineering. Concluding, we present the black-oil model, the compositional model and the complex models as applied to petroleum field applications.

Comparative CFD and Simulative Analysis of Flow Behaviour to Calculate Losses in Different Geometrical Pipes

Comparative CFD and Simulative Analysis of Flow Behaviour to Calculate Losses in Different Geometrical Pipes

Flow behaviour analysis through a venturi designed for industrial and environmental processes

The immense environmental challenges facing the world today and in the years to come can be met only through mobilizing the best engineers and scientists in the environmental sector and using innovative and cost-effective solutions. Hydraulic structures can significantly improve dissolved oxygen levels by creating turbulent conditions in which small air bubbles are caused in most of the flow. Therefore, a venturi device can be used as highly effective aerator in aeration processes. However, the hydraulic equipment can be exposed to anomalies due to pressure variations. This is generally caused by the air phase development. Moreover, it considerably induces wall materials, erosion and corrosion. In this work, particular attention was paid to the pressure change in closed venturi pipes because its decrease generates air bubbles and its increase implies their implosion. Both mathematical and experimental tools were used to describe the pressure evolution with flow rates and air bubbles size. Experimental tests were carried out using a transparent rectangular venturi. Pressure field and air section length were measured for different coming flow rates of water. On the other hand, the Rayleigh Plesset ordinary differential equation was used to explain this phenomenon under spherical bubbles hypothesis. High values of the Reynolds dimensionless numbers, at both the upstream and throat sections, indicate a fully turbulent flow through the venturi. Inception was visualized when the air phase starts, before the pressure attains the vapour value. The mathematical model solution shows three flow zones for the pressure field evolution with the relationship between air bubble radius and liquid phase size. So, an unstable flow, inception and a stable cavitating flow were highlighted. Also, the experimental results allow distinguishing these zones depending on the flow rate values. The flow parameters, Reynolds and Thomas dimensionless numbers influence simultaneously the air phase extent. Thus, the present study connects the Rayleigh Plesset equation to turbulence and cavitation flow parameters. This allowed a new flow analysis through a venturi considered by its air phase development.

Simulation of Gas Production from Multilayered Hydrate-Bearing Media with Fully Coupled Flow, Thermal, Chemical and Geomechanical Processes Using TOUGH+Millstone. Part 3: Production Simulation Results

The TOUGH+Millstone simulator has been developed for the analysis of coupled flow, thermal and geomechanical processes associated with the formation and/or dissociation of $$\hbox {CH}_{4}$$ -hydrates in geological media. It is composed of two constituent codes: (a) a significantly enhanced version of the TOUGH+Hydrate simulator, v2.0, that accounts for all known flow, physical, thermodynamic and chemical processes associated with the evolution of hydrate-bearing systems and includes the most recent physical properties relationships, coupled seamlessly with (b) Millstone v1.0, a new code that addresses the conceptual, computational and mathematical shortcomings of earlier codes used to describe the geomechanical response of these systems. The capabilities of the TOUGH+Millstone code are demonstrated in the simulation and analysis of the system flow, thermal, and geomechanical behavior during gas production from a realistic complex offshore hydrate deposit. In the third paper of this series, we apply the simulators described in parts 1 and 2 to a problem of gas production from a complex, multilayered system of hydrate-bearing sediments in an oceanic environment. We perform flow simulations of constant-pressure production via a vertical well and compare those results to a coupled flow-geomechanical simulation of the same process. The results demonstrate the importance of fully coupled geomechanics when modeling the evolution of reservoir properties during production.

Simulation of Gas Production from Multilayered Hydrate-Bearing Media with Fully Coupled Flow, Thermal, Chemical and Geomechanical Processes Using TOUGH + Millstone. Part 1: Numerical Modeling of Hydrates

TOUGH + Millstone has been developed for the analysis of coupled flow, thermal and geomechanical processes associated with the formation and/or dissociation of CH4-hydrates in geological media. It is composed of two constituent codes: (a) a significantly enhanced version of the TOUGH + HYDRATE simulator, V2.0, that accounts for all known flow, physical, thermodynamic and chemical processes associated with the behavior of hydrate-bearing systems undergoing changes and includes the most recent advances in the description of the system properties, coupled seamlessly with (b) Millstone V1.0, a new code that addresses the conceptual, computational and mathematical shortcomings of earlier codes used to describe the geomechanical response of these systems. The capabilities of TOUGH + Millstone are demonstrated in the simulation and analysis of the system flow, thermal and geomechanical behavior during gas production from a realistic complex offshore hydrate deposit. In the first paper of this series, we discuss the physics underlying the T + H hydrate simulator, the constitutive relationships describing the physical, chemical (equilibrium and kinetic) and thermal processes, the states of the $${\hbox {CH}}_4 + {\hbox {H}}_2 \hbox {O}$$ system and the sources of critically important data, as well as the mathematical approaches used for the development of the of mass and energy balance equations and their solution. Additionally, we provide verification examples of the hydrate code against numerical results from the simulation of laboratory and field experiments.

Simulation of Gas Production from Multilayered Hydrate-Bearing Media with Fully Coupled Flow, Thermal, Chemical and Geomechanical Processes Using TOUGH+Millstone. Part 2: Geomechanical Formulation and Numerical Coupling

The TOUGH+Millstone simulator has been developed for the analysis of coupled flow, thermal and geomechanical processes associated with the formation and/or dissociation of $$\hbox {CH}_{4}$$ hydrates in geological media. It is composed of two constituent codes: (a) a significantly enhanced version of the TOUGH+HYDRATE simulator, v2.0, that accounts for all known flow, physical, thermodynamic and chemical processes associated with the behavior of hydrate-bearing systems undergoing changes and includes the most recent advances in the description of the system properties, coupled seamlessly with (b) Millstone v1.0, a new code that addresses the conceptual, computational and mathematical shortcomings of earlier codes used to describe the geomechanical response of these systems. The capabilities of the TOUGH+Millstone code are demonstrated in the simulation and analysis of the system flow, thermal and geomechanical behavior during gas production from a realistic complex offshore hydrate deposit. In the second part of this series, we describe the Millstone geomechanical simulator. The hydrate-dependent, rate-based poromechanical formulation is presented and solved using a finite element discretization. A novel multimesh coupling scheme is introduced, wherein interpolators are automatically built to transfer data between the finite difference discretization of TOUGH+ and the finite element discretization of Millstone. We provide verification examples against analytic solutions for poroelasticity and a simplified demonstration problem for mechanically induced phase change in a hydrate sediment.

Analysis of flow behavior and fluid forces in large cylinder bundles by numerical simulations

This paper presents a numerical investigation of the three-dimensional flow around an in-line cylinder arrangement with up to twenty-five cylinders under confinement, with a subcritical Reynolds number, in the context of flow-induced vibrations. Flow characteristics and patterns, as well as the force coefficients of the cylinders and Strouhal numbers were evaluated numerically with the large eddy simulation approach and validated against previously published experimental data. Two values for both the transversal (T/D = 1.5 and 3) and longitudinal (L/D = 2 and 4) spacing ratios were considered and combined to generate four different arrangements. The velocity distributions obtained in the simulations were in good agreement with the experimental data. Fluctuations in the force coefficients were characterized for each arrangement and found to be directly proportional to the turbulence kinetic energy upstream of each cylinder. Depending on the flow pattern, certain rows are subjected to greater flow force fluctuations. The dominant frequency, expressed by the Strouhal number, was also mapped throughout the arrangements and its distribution was characterized according to the observed flow patterns. Although the spacing ratios have a combined effect, their separate influence on the general behavior and distribution of fluid forces could be identified, as these are linked to the flow regimes. This knowledge allowed for the contribution to an already existing in-line tube bundle classification, which is useful in the diagnosis of flow-induced vibrations and the design of heat exchangers and other industrial equipment.

Simulation of Sand Filling Process and Analysis of Flow Behavior with Different Binder Ratio

Core shooting process has a great influence on the quality of sand cores. At present, there are two computational fluid dynamic models applied to simulate the hydrodynamics of core shooting process. In this paper, a two-fluid model (TFM) simulation is made on fluid dynamic analysis. With validation of experimental results and discrete particle model (DPM) simulations, the TFM is able to predict a reasonable flow behavior of sand particles by gas dynamic pressure analysis. Residual gas distribution of sand filling process is analyzed and a good agreement is achieved between air volume fraction simulation based on TFM and experimental results. A comparison between different binder ratios is made. The binder ratio has a significant effect on sand hydrodynamic behavior and the sand volume fraction.

Flow behavior analysis of confined fluid in a flexible tube: application of asymptotic approach

In this paper, we asymptotically investigate a confined fluid flow in a flexible tube with a variable section. The fluid is considered to be newtonian, incompressible and it elapses in elastic and isotropic shell. This study provides a review of recent analysing the effects of the elastic wall tube properties over the fluid behaviour. The unsteady fluid flow will be analysed following the singular perturbations theory according to a large Reynolds number and a small aspect radio. The wall is assumed to be a thin shell that generate a small axisymmetric vibration. This model is mathematically developed by using the thin shell linear theory that is governed by a geodesic curvature parameter.

Rheological Behavior of Fresh Cement Pastes

Rheology of a concrete is mainly controlled by the rheological behavior of its cement paste. This is the main practical reason for the extensive research activity observed during 70 years in this research subfield. In this brief review, some areas of the research on the rheological behavior of fresh cement pastes (mixture method influence, microstructure analysis, mineral additions influence, chemical additives influence, blended cements behavior, viscoelastic behavior, flow models, and flow behavior analysis with alternative methods) are examined.

Comparisons of flow behavior characteristics and microstructure between asymmetrical shear rolling and symmetrical rolling by macro/micro coupling simulation

A new rolling method of asymmetrical shear rolling is applied to solve heterogeneous strain and uneven microstructure distribution of thick plate preparation in symmetrical rolling. Coupled finite element models (FEM) and cellular automata (CA) models are established to compare strain and temperature characteristics and microstructure evolution during multi-pass rolling of two rolling ways. Different recrystallization mechanisms are taken into consideration in coupled models of multi-pass rolling. The results show that equivalent strain distribution is asymmetrical in asymmetrical shear rolling and the value at center point is 16% larger than that in symmetrical rolling due to accumulated shear deformation. The temperature at lower layer of the plate in asymmetrical shear rolling is higher, which results in faster metal flow and larger strain. The temperature variations in relation to time at different positions of the plate are fitted. Microstructure evolution for multi-pass rolling is studied and higher recrystallization fraction and finer grain size appear at center point of plate in asymmetrical shear rolling. Rolling experiments are conducted and the results of strain and microstructure agree with simulation results. The coupled models provide guidance for flow behavior and microstructure analysis at macro/micro level.

Transient model analysis of gas flow behavior for a multi-fractured horizontal well incorporating stress-sensitive permeability

The assumption of constant reservoir permeability is not strictly applicable to reservoirs where rock properties undergo changes, such as stress-sensitive porous media. Most researches on the permeability stress sensitivity mainly concentrated on experimental approach, physical modeling or pressure transient analysis, whereas rate transient analysis does not attract much attention. Based on source/sink function method, this paper develops a seepage model of multi-fractured horizontal well incorporating stress-sensitive permeability. The model is semi-analytically solved by fracture discretization, Pedrosa’s transformation, perturbation theory, and integration transformation method. Not only pressure transient analysis, but also rate transient analysis is separately performed with relevant parameters. The model presented here can provide some insights into well dynamic forecasting during exploiting such reservoirs, and contribute to establish the theoretical basic for transient analysis efficiently.

Searching for a Stable High-Performance Magnetorheological Suspension.

Magnetorheological (MR) fluids are a type of smart material with rheological properties that may be controlled through mesostructural transformations. MR fluids form solid-like fibril structures along the magnetic field direction upon application of a magnetic field due to magnetopolarization of soft-magnetic particles when suspended in an inert medium. A reverse structural transition occurs upon removal of the applied field. The structural changes are very fast on the order of milliseconds. The rheological properties of MR fluids vary with the application of a magnetic field, resulting in non-Newtonian viscoplastic flow behaviors. Recent applications have increased the demand for MR materials with better performance and good long-term stability. A variety of industrial MR materials have been developed and tested in numerous experimental and theoretical studies. Because modeling and analysis are essential to optimize material design, a new macroscale structural model has been developed to distinguish between static yield stress and dynamic yield stress and describe the flow behavior over a wide range of shear rates. Herein, this recent progress in the search for advanced MR fluid materials with good stability is described, along with new approaches to MR flow behavior analysis. Several ways to improve the stability and efficiency of the MR fluids are also summarized.