scholarly journals Application of Higher-Order TVD Resolution for Investigation of Transients Problems in Natural Gas Pipelines

1996 ◽  
Author(s):  
Sarafa O. Ibraheem ◽  
Michael A. Adewumi
Keyword(s):  
Natural Gas ◽  
Hyperbolic Equations ◽  
Numerical Procedure ◽  
Higher Order ◽  
Transient Phenomena ◽  
Natural Gas Pipelines ◽  
Tvd Method ◽  
Base Solution ◽  
Wide Range ◽  
Upwind Methods

A higher-order numerical procedure is applied to simulate typical transient phenomena in natural gas transportation. Reliable modeling and prediction of transients features in transmission pipelines are desirable for optimal control of gas deliverability, design and implementation of active controls, and modeling of operational behavior of network peripheral equipment (e.g., chokes, valves, compressors, etc.). As an alternative to the Method of Characteristics (MOC) that is widely used presently, a higher-order Total Variation Diminishing (TVD) method is used to model some transient problems. This, class of methods has the capability to capture fine-scale phenomena and provides a better resolution of frontal discontinuities. In this study, the TVD method is utilized in conjunction with upwind methods. Also, in order to ensure a stable time-stepping scheme over a wide range of Courant-Friedrich-Lewy (CFL) number, a special Runge-Kutta method is employed as the base solution algorithm to integrate the highly non-linear, hyperbolic equations which govern the transportation of natural gas in pipelines. The overall procedure is stable, robust and accurate when applied to solve practical problems with simulated pressure waves.

On Total Variation Diminishing Schemes for Pressure Transients

1999 ◽  
Vol 121 (2) ◽  
pp. 122-130 ◽  
Author(s):  
S. O. Ibraheem ◽  
M. A. Adewumi
Keyword(s):  
Natural Gas ◽  
Total Variation ◽  
Hyperbolic Equations ◽  
Numerical Procedure ◽  
Higher Order ◽  
Nonlinear Hyperbolic Equations ◽  
Total Variation Diminishing ◽  
Variation Diminishing ◽  
Highly Nonlinear ◽  
Wide Range

A higher-order numerical procedure is applied to simulate typical transient phenomena in natural gas transportation. Reliable modeling and prediction of transients features in transmission pipelines are desirable for optimal control of gas deliverability, design and implementation of active controls, and modeling of operational behavior of network peripheral equipment (e.g., chokes, valves, compressors, etc.). As an alternative to the method of characteristics (MOC) that had been widely used for modeling these systems, higher-order total variation diminishing (TVD) methods are used to model some transient problems. This class of methods has the capability of capturing fine-scale phenomena, and they do provide a better resolution of frontal discontinuities. In this study, the TVD schemes are utilized in conjunction with upwind methods. Also, in order to ensure a stable time-stepping scheme over a wide range of Courant-Friedrich-Lewy (CFL) number, a special Runge-Kutta method is employed as the base solution algorithm to integrate the highly nonlinear, hyperbolic equations which govern the transportation of natural gas in pipelines. The overall procedure is stable, robust, and accurate when applied to solve practical problems with dynamic pressure waves.

A Higher-Order Theory for Vibration Analysis of Curvilinear Thick Shallow Shells with Constrained Boundaries

1995 ◽  
Vol 1 (1) ◽  
pp. 15-39 ◽  
Author(s):  
K.M. Liew ◽  
C.W. Lim
Keyword(s):  
Shear Strain ◽  
Transverse Shear ◽  
Vibration Analysis ◽  
Numerical Procedure ◽  
Higher Order ◽  
Mode Shapes ◽  
Transverse Shear Strain ◽  
Shallow Shells ◽  
Displacement Mode ◽  
Wide Range

This article presents the vibration analysis of thick doubly curved shallow shells having curvilinear planform. The Gaussian curvature of shell varies from positive (such as spherical) to negative (such as hyperbolic paraboloidal). The boundaries are constrained with either soft-simply supported or fully clamped edges. A higher-order shear deformation theory, which includes transverse shear strain and rotary inertia, is developed to model the vibration characteristics of the shell. The inclusion of Lamé parameters in the present formulation accounts for the presence of shell curvature and yields cubic transverse shear strain distribution in contrast with the existing quadratic expressions. A set of versatile, globally continuous shape functions is adopted in the Ritz numerical procedure to approximate the displacement and rotation fields. A set of new results for a wide range of shell configurations is presented with some selected contour and three-dimensional displacement mode shapes.

scholarly journals An Investigation into the Volumetric Flow Rate Requirement of Hydrogen Transportation in Existing Natural Gas Pipelines and Its Safety Implications

Gases ◽  
2021 ◽  
Vol 1 (4) ◽  
pp. 156-179
Author(s):  
Abubakar Jibrin Abbas ◽  
Hossein Hassani ◽  
Martin Burby ◽  
Idoko Job John
Keyword(s):  
Natural Gas ◽  
Flow Rate ◽  
Compressibility Factor ◽  
Volumetric Flow Rate ◽  
Gas Pipeline ◽  
Internal Erosion ◽  
Gas Pipelines ◽  
Natural Gas Pipelines ◽  
Natural Gas Pipeline ◽  
Wide Range

As an alternative to the construction of new infrastructure, repurposing existing natural gas pipelines for hydrogen transportation has been identified as a low-cost strategy for substituting natural gas with hydrogen in the wake of the energy transition. In line with that, a 342 km, 36″ natural gas pipeline was used in this study to simulate some technical implications of delivering the same amount of energy with different blends of natural gas and hydrogen, and with 100% hydrogen. Preliminary findings from the study confirmed that a three-fold increase in volumetric flow rate would be required of hydrogen to deliver an equivalent amount of energy as natural gas. The effects of flowing hydrogen at this rate in an existing natural gas pipeline on two flow parameters (the compressibility factor and the velocity gradient) which are crucial to the safety of the pipeline were investigated. The compressibility factor behaviour revealed the presence of a wide range of values as the proportions of hydrogen and natural gas in the blends changed, signifying disparate flow behaviours and consequent varying flow challenges. The velocity profiles showed that hydrogen can be transported in natural gas pipelines via blending with natural gas by up to 40% of hydrogen in the blend without exceeding the erosional velocity limits of the pipeline. However, when the proportion of hydrogen reached 60%, the erosional velocity limit was reached at 290 km, so that beyond this distance, the pipeline would be subject to internal erosion. The use of compressor stations was shown to be effective in remedying this challenge. This study provides more insights into the volumetric and safety considerations of adopting existing natural gas pipelines for the transportation of hydrogen and blends of hydrogen and natural gas.

Numerical Simulation of Hydrate Transport in Natural Gas Pipeline

1998 ◽  
Vol 120 (1) ◽  
pp. 20-26 ◽  
Author(s):  
S. O. Ibraheem ◽  
M. A. Adewumi ◽  
J. L. Savidge
Keyword(s):  
Natural Gas ◽  
Fluid Model ◽  
Hydrate Formation ◽  
Higher Order ◽  
Solid Particles ◽  
Natural Gas Pipelines ◽  
Natural Gas Pipeline ◽  
Offshore Production ◽  
Two Fluid Model ◽  
Viable Approach

Accurate modeling of hydrate transportation in natural gas pipelines is becoming increasingly important in the design and operation of offshore production facilities. The dynamics involved in the formation of hydrate particles and in its transportation are governed by the multiphase hydrodynamics equations ensuing from the balance of mass, momentum, and energy. In this study, a two-fluid model is solved to characterize particulate transportation. The numerical algorithm employed is stable and robust and it is based on higher-order schemes. This is necessary since the governing equations describing the simultaneous flow of gas and solid particles are hyperbolic and, thus, admit discontinuities. Specialized higher-order schemes provide a viable approach for efficient frontal tracking of continuity waves in particular. Several simulation experiments that can facilitate thorough understanding of the design and maintenance of pipelines susceptible to hydrate formation are presented.

Limit States Design and Assessment of Onshore Pipelines

2012 ◽  
Author(s):  
Maher Nessim
Keyword(s):  
Natural Gas ◽  
Development Stage ◽  
Simple Design ◽  
Safety Factors ◽  
Limit States ◽  
Natural Gas Pipelines ◽  
Reliability Based Design ◽  
Wide Range ◽  
Assessment Standard ◽  
Expected Outcomes

In 2005, guidelines for the application of reliability-based design and assessment (RBDA) to natural gas pipelines were developed under PRCI sponsorship. The methodology underlying these guidelines has since been adopted as a non-mandatory Annex in the CSA Z662 standard (Annex O). The benefits of reliability-based methods include consistent safety levels, optimized solutions that make best use of available resources and flexibility in addressing non-standard problems. The key limitations of the methodology are that it requires specialized expertise, good data and a significant analysis effort. One approach that has been successfully used to simplify the application of reliability-based methods is to develop simple design and assessment rules that are designed to meet specified safety levels. In this approach, which is referred to here as limit states design and assessment, the checking rules incorporate safety factors that are “calibrated” to meet pre-selected reliability targets, within a specified tolerance, over a wide range of possible design and assessment cases. Probabilistic analyses are performed as part of the development stage, but the resulting checks are deterministic. The basic elements required to calibrate limit states design and assessment checks have been developed as part of the RBDA methodology, making the development of a limit states approach feasible. This paper provides an overview of an ongoing Joint Industry Project to develop a limit states design and assessment standard that addresses the key threats to the safety of onshore pipelines. The benefits and limitations of this approach are discussed in comparison to the full RBDA approach, and the expected outcomes of the project are described.

Current Trends in Biotherapeutic Higher Order Structure Characterization by Irreversible Covalent Footprinting Mass Spectrometry

2019 ◽  
Vol 26 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Natalie K. Garcia ◽  
Galahad Deperalta ◽  
Aaron T. Wecksler
Keyword(s):  
Mass Spectrometry ◽  
Protein Structure ◽  
Protein Interactions ◽  
Quaternary Structure ◽  
Solvent Accessibility ◽  
Higher Order ◽  
Structure Characterization ◽  
Order Structure ◽  
Protein Footprinting ◽  
Wide Range

Background: Biotherapeutics, particularly monoclonal antibodies (mAbs), are a maturing class of drugs capable of treating a wide range of diseases. Therapeutic function and solutionstability are linked to the proper three-dimensional organization of the primary sequence into Higher Order Structure (HOS) as well as the timescales of protein motions (dynamics). Methods that directly monitor protein HOS and dynamics are important for mapping therapeutically relevant protein-protein interactions and assessing properly folded structures. Irreversible covalent protein footprinting Mass Spectrometry (MS) tools, such as site-specific amino acid labeling and hydroxyl radical footprinting are analytical techniques capable of monitoring the side chain solvent accessibility influenced by tertiary and quaternary structure. Here we discuss the methodology, examples of biotherapeutic applications, and the future directions of irreversible covalent protein footprinting MS in biotherapeutic research and development. Conclusion: Bottom-up mass spectrometry using irreversible labeling techniques provide valuable information for characterizing solution-phase protein structure. Examples range from epitope mapping and protein-ligand interactions, to probing challenging structures of membrane proteins. By paring these techniques with hydrogen-deuterium exchange, spectroscopic analysis, or static-phase structural data such as crystallography or electron microscopy, a comprehensive understanding of protein structure can be obtained.

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