Influence of Flow Geometry on Sandface Temperatures During Single-Phase Oil Production: Dimensionless Analysis

SPE Journal ◽  
2016 ◽  
Vol 21 (03) ◽  
pp. 0928-0937 ◽  
Author(s):  
J. F. App
Keyword(s):  
Steady State ◽  
Flow Regime ◽  
Transient Analysis ◽  
Numerical Solutions ◽  
Temperature Behavior ◽  
Transient Temperature ◽  
Linear Flow ◽  
Dimensionless Analysis ◽  
Flow Geometry ◽  
The Impact

Summary This paper evaluates the impact of flow geometry on sandface temperature behavior under conditions of high drawdown in which Joule-Thomson thermal effects are significant. The temperature behavior of both radial- and linear-flow regimes is evaluated under steady-state and transient conditions. Through a dimensionless analysis of the thermal-energy equation, a systematic evaluation of the contributing terms is presented. The steady-state analysis is based on analytic solutions that demonstrate identical temperature behavior at asymptotic limits but are offset by a geometric factor at intermediary Péclet numbers. The transient analysis is based on a combination of analytical and numerical solutions. The transient analysis demonstrates that temperature changes occur earlier in time for the radial geometry compared with the linear geometry. The impetus behind this study is to address the impact of transient-temperature development in hydraulically fractured vs. nonhydraulically fractured vertical completions. The flow regime in nonhydraulically fractured vertical completions is radial whereas in hydraulically fractured vertical completions a linear-flow regime can dominate a significant portion of the flow history. All analyses assume that skin, wellbore-storage, and thermal-storage effects are negligible.

SEMI-ANALYTICAL SOLUTIONS FOR THE BRUSSELATOR REACTION–DIFFUSION MODEL

2017 ◽  
Vol 59 (2) ◽  
pp. 167-182 ◽  
Author(s):  
H. Y. ALFIFI
Keyword(s):  
Steady State ◽  
Hopf Bifurcation ◽  
Partial Differential Equations ◽  
Differential Equations ◽  
Analytical Solutions ◽  
Numerical Solutions ◽  
Partial Differential ◽  
Analytical Results ◽  
Transient Solutions ◽  
The Impact

Semi-analytical solutions are derived for the Brusselator system in one- and two-dimensional domains. The Galerkin method is processed to approximate the governing partial differential equations via a system of ordinary differential equations. Both steady-state concentrations and transient solutions are obtained. Semi-analytical results for the stability of the model are presented for the identified critical parameter value at which a Hopf bifurcation occurs. The impact of the diffusion coefficients on the system is also considered. The results show that diffusion acts to stabilize the systems better than the equivalent nondiffusive systems with the increasing critical value of the Hopf bifurcation. Comparison between the semi-analytical and numerical solutions shows an excellent agreement with the steady-state transient solutions and the parameter values at which the Hopf bifurcations occur. Examples of stable and unstable limit cycles are given, and Hopf bifurcation points are shown to confirm the results previously calculated in the Hopf bifurcation map. The usefulness and accuracy of the semi-analytical results are confirmed by comparison with the numerical solutions of partial differential equations.

A steady-state and transient analysis of the electron transport that occurs within bulk wurtzite zinc-magnesium-oxide alloys subjected to high-fields

MRS Advances ◽  
2018 ◽  
Vol 3 (59) ◽  
pp. 3439-3444 ◽  
Author(s):  
Poppy Siddiqua ◽  
Walid A. Hadi ◽  
Michael S. Shur ◽  
Stephen K. O’Leary
Keyword(s):  
Steady State ◽  
Electron Transport ◽  
Magnesium Oxide ◽  
Transient Analysis ◽  
Alloy System ◽  
Magnesium Content ◽  
High Fields ◽  
Zinc Magnesium Oxide ◽  
The Impact ◽  
Bulk Alloys

ABSTRACTWe present some recently acquired results corresponding to the nature of the electron transport that occurs within bulk alloys of zinc-magnesium-oxide. These results are obtained using three-valley ensemble semi-classical Monte Carlo electron transport simulations. The impact that the magnesium content plays in shaping the form of the electron transport related characteristics associated with this alloy system is explored. Both steady-state and transient electron transport results are examined. The device implications of these results are then commented upon.

scholarly journals Steady-state and transient heat transfer through fins of complex geometry

2014 ◽  
Vol 35 (2) ◽  
pp. 117-133 ◽  
Author(s):  
Dawid Taler ◽  
Jan Taler
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Temperature Distribution ◽  
Transient Analysis ◽  
Complex Geometry ◽  
Transient Temperature ◽  
Heat Flow Rate ◽  
Approximate Methods ◽  
Fin Efficiency ◽  
Transient Temperature Distribution

Abstract Various methods for steady-state and transient analysis of temperature distribution and efficiency of continuous-plate fins are presented. For a constant heat transfer coefficient over the fin surface, the plate fin can be divided into imaginary rectangular or hexangular fins. At first approximate methods for determining the steady-state fin efficiency like the method of equivalent circular fin and the sector method are discussed. When the fin geometry is complex, thus transient temperature distribution and fin efficiency can be determined using numerical methods. A numerical method for transient analysis of fins with complex geometry is developed. Transient temperature distributions in continuous fins attached to oval tubes is computed using the finite volume - finite element methods. The developed method can be used in the transient analysis of compact heat exchangers to calculate correctly the heat flow rate transferred from the finned tubes to the fluid.

Linear vs. Radial Boundary-Dominated Flow: Implications for Gas-Well-Decline Analysis

SPE Journal ◽  
2015 ◽  
Vol 20 (05) ◽  
pp. 1053-1066 ◽  
Author(s):  
Pichit Vardcharragosad ◽  
Luis F. Ayala ◽  
Miao Zhang
Keyword(s):  
Radial Flow ◽  
Transient Flow ◽  
Transient Behavior ◽  
Late Time ◽  
Gas Reservoirs ◽  
Linear Flow ◽  
Unconventional Resources ◽  
Flow Geometry ◽  
Fast Pace ◽  
The Impact

Summary Linear flow is a fundamental reservoir-flow geometry typically associated with production from unconventional resources stimulated by means of hydraulic fracturing. Recently, linear flow has been intensively studied following the fast pace of development of unconventional resources. Previous studies have mainly focused on early transient behavior and behavior of composite linear-flow systems. In this work, a density-based analysis method is extended to study decline behavior of the linear-flow system in boundary-dominated flow (BDF). In this study, we first discuss traditional approaches used to model linear flow in gas reservoirs. Second, we show the applicability of the density-based method for gas linear flow both analytically and numerically. Next, late-time solutions are discussed, and the analytical forecasting solution that best describes the BDF behavior is selected for long-term decline-behavior studies. Previously reported results on radial flow as well as early transient-flow effect are also incorporated to provide a more complete understanding of decline behavior and the impact of flow geometry. We show that boundary-dominated responses in linear-flow scenarios fully develop at much later stages of reservoir depletion compared with radial-flow scenarios. As a result, and in marked contrast with radial flow, purely hyperbolic decline behavior may be completely lost in linear-flow scenarios during boundary-dominated conditions. It is demonstrated that most of the recoverable hydrocarbons are produced during the early transient period for linear-flow conditions, whereas most of them are recovered during the BDF period for radial flow. These results suggest that the availability of accurate early transient models is much more critical for the formulation of linear-flow-decline models than had been traditionally necessary for radial-flow-decline models.

scholarly journals Bridging the Gap between Economic Modelling and Simulation: A Simple Dynamic Aggregate Demand-Aggregate Supply Model with Matlab

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
José M. Gaspar
Keyword(s):  
Steady State ◽  
Numerical Solutions ◽  
Aggregate Demand ◽  
Economic Modelling ◽  
Aggregate Supply ◽  
Parameter Values ◽  
The Impact ◽  
The Relationship ◽  
Fiscal And Monetary Policy ◽  
Simulations In Economics

This paper aims to connect the bridge between analytical results and the use of the computer for numerical simulations in economics. We address the analytical properties of a simple dynamic aggregate demand and aggregate supply (AD-AS) model and solve it numerically. The model undergoes a bifurcation as its steady state smoothly interchanges stability depending on the relationship between the impact of real interest rate on demand for liquidity and how fast agents revise their expectations on inflation. Using code embedded into a unique function in Matlab, we plot the numerical solutions of the model and simulate different dynamic adjustments using different parameter values. The same function also accommodates the analysis of the impacts of fiscal and monetary policy and supply side shocks on the steady state and the transition dynamics of the model.

Instability and Collapse in Discrete Wave Equations

2005 ◽  
Vol 5 (3) ◽  
pp. 223-241
Author(s):  
A. Carpio ◽  
G. Duro
Keyword(s):  
Continuum Limit ◽  
Wave Equations ◽  
Numerical Solutions ◽  
Blow Up ◽  
Theoretical Predictions ◽  
Initial States ◽  
The Impact ◽  
The Continuum

AbstractUnstable growth phenomena in spatially discrete wave equations are studied. We characterize sets of initial states leading to instability and collapse and obtain analytical predictions for the blow-up time. The theoretical predictions are con- trasted with the numerical solutions computed by a variety of schemes. The behavior of the systems in the continuum limit and the impact of discreteness and friction are discussed.

scholarly journals Advanced Constitutive Modeling of the Thixotropic Elasto-Visco-Plastic Behavior of Blood: Steady-State Blood Flow in Microtubes

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 367
Author(s):  
Konstantinos Giannokostas ◽  
Yannis Dimakopoulos ◽  
Andreas Anayiotos ◽  
John Tsamopoulos
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Constitutive Model ◽  
Blood Plasma ◽  
Constitutive Modeling ◽  
Flow Direction ◽  
Momentum Balance ◽  
Plastic Behavior ◽  
Flow Investigation ◽  
The Impact

The present work focuses on the in-silico investigation of the steady-state blood flow in straight microtubes, incorporating advanced constitutive modeling for human blood and blood plasma. The blood constitutive model accounts for the interplay between thixotropy and elasto-visco-plasticity via a scalar variable that describes the level of the local blood structure at any instance. The constitutive model is enhanced by the non-Newtonian modeling of the plasma phase, which features bulk viscoelasticity. Incorporating microcirculation phenomena such as the cell-free layer (CFL) formation or the Fåhraeus and the Fåhraeus-Lindqvist effects is an indispensable part of the blood flow investigation. The coupling between them and the momentum balance is achieved through correlations based on experimental observations. Notably, we propose a new simplified form for the dependence of the apparent viscosity on the hematocrit that predicts the CFL thickness correctly. Our investigation focuses on the impact of the microtube diameter and the pressure-gradient on velocity profiles, normal and shear viscoelastic stresses, and thixotropic properties. We demonstrate the microstructural configuration of blood in steady-state conditions, revealing that blood is highly aggregated in narrow tubes, promoting a flat velocity profile. Additionally, the proper accounting of the CFL thickness shows that for narrow microtubes, the reduction of discharged hematocrit is significant, which in some cases is up to 70%. At high pressure-gradients, the plasmatic proteins in both regions are extended in the flow direction, developing large axial normal stresses, which are more significant in the core region. We also provide normal stress predictions at both the blood/plasma interface (INS) and the tube wall (WNS), which are difficult to measure experimentally. Both decrease with the tube radius; however, they exhibit significant differences in magnitude and type of variation. INS varies linearly from 4.5 to 2 Pa, while WNS exhibits an exponential decrease taking values from 50 mPa to zero.

Urban hydrogeomorphology and the urban stream syndrome

2015 ◽  
Vol 40 (3) ◽  
pp. 480-492 ◽  
Author(s):  
Geoff J. Vietz ◽  
Christopher J. Walsh ◽  
Tim D. Fletcher
Keyword(s):  
Flow Regime ◽  
Stormwater Runoff ◽  
Control Measures ◽  
Urban Stream ◽  
Urban Stream Syndrome ◽  
Stream Morphology ◽  
Research Areas ◽  
Urban Catchments ◽  
Urban Stormwater Runoff ◽  
The Impact

The urban stream syndrome is an almost universal physical and ecological response of streams to catchment urbanization. Altered channel geomorphology is a primary symptom that includes channel deepening, widening and instability. While the common approach is to treat the symptoms (e.g. modifying and stabilizing the channel), many stream restoration objectives will not be achieved unless the more vexing problem, treating the cause, is addressed in some way. Research demonstrates that the dominant cause of geomorphic change in streams in urban catchments is an altered flow regime and increase in the volume of stormwater runoff. Thus, managers can choose to treat the symptoms by modifying and controlling the channel to accommodate the altered flow regime, or treat the cause by modifying the flow regime to reduce the impact on channel morphology. In both cases treatments must, at the least, explicitly consider hydrogeomorphology—the science of the linkages between various hydrologic and geomorphic processes—to have a chance of success. This paper provides a review of recent literature (2010 to early 2015) to discuss fluvial hydrogeomorphology in the management of streams subject to urbanization. We suggest that while the dominant approach is focused on combating the symptoms of catchment urbanization (that we refer to as channel reconfiguration), there is increasing interest in approaches that attempt to address the causes by using stormwater control measures at a range of scales in the catchment (e.g. flow-regime management). In many settings in the oft-constrained urban catchment, effective management of stream morphology may require multiple approaches. To conclude, we identify five research areas that could inform urban hydrogeomorphology, one of the most challenging of which is the extent to which the volume of excess urban stormwater runoff can be reduced to mitigate the impact on stream geomorphology.

Experimental and Theoretical Analysis of Transient Response of Plate Heat Exchangers in Presence of Nonuniform Flow Distribution

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
N. Srihari ◽  
Sarit K. Das
Keyword(s):  
Steady State ◽  
Heat Exchangers ◽  
Sudden Change ◽  
Temperature Response ◽  
Flow Distribution ◽  
Transient Temperature ◽  
Nonuniform Flow ◽  
Flow Rates ◽  
Plate Heat ◽  
Flow Maldistribution

Transient analysis helps us to predict the behavior of heat exchangers subjected to various operational disturbances due to sudden change in temperature or flow rates of the working fluids. The present experimental analysis deals with the effect of flow distribution on the transient temperature response for U-type and Z-type plate heat exchangers. The experiments have been carried out with uniform and nonuniform flow distributions for various flow rates. The temperature responses are analyzed for various transient characteristics, such as initial delay and time constant. It is also possible to observe the steady state characteristics after the responses reach asymptotic values. The experimental observations indicate that the Z-type flow configuration is more strongly affected by flow maldistribution compared to the U-type in both transient and steady state regimes. The comparison of the experimental results with numerical solution indicates that it is necessary to treat the flow maldistribution separately from axial thermal dispersion during modeling of plate heat exchanger dynamics.

Floating Roof Influence on Seismic Response of Large Vertical Storage Tank

2013 ◽  
Vol 671-674 ◽  
pp. 1399-1402
Author(s):  
Ying Sun ◽  
Jian Gang Sun ◽  
Li Fu Cui
Keyword(s):  
Seismic Response ◽  
Storage Tank ◽  
Numerical Solutions ◽  
Fluid Pressure ◽  
Seismic Intensity ◽  
Site Conditions ◽  
Storage Tanks ◽  
Analysis Model ◽  
Base Shear ◽  
The Impact

To study the impact of floating roof on seismic response of vertical storage tank structure system subjected to seismic excitation, select 150000m3 storage tanks as research object, and the finite element analysis model of storage tanks with and without floating roof were established respectively. The seismic response of these two types of structure in different site conditions and seismic intensity were calculated and the numerical solutions were compared. The results show that floating roof has little impact on base shear and base moment in different site conditions and seismic intensity. Floating roof can effectively reduce the sloshing wave height. The influence of floating roof on dynamic fluid pressure decreases with the increase of seismic intensity, which is less affected by ground conditions.

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