Numerical Evaluation of the Pressure Drop in Multiphase Flow of the Catenary Riser with the Presence of Leakage

2016 ◽  
Vol 366 ◽  
pp. 157-165
Author(s):  
Daniela Passos Simões de Almeida Tavares ◽  
Lígia Rafaely Barbosa Sarmento ◽  
Enivaldo Santos Barbosa ◽  
Severino Rodrigues de Farias Neto ◽  
Antonio Gilson Barbosa de Lima
Keyword(s):  
Multiphase Flow ◽  
Structural Integrity ◽  
Volume Fraction ◽  
Computational Techniques ◽  
Oil Well ◽  
Pipe Material ◽  
Noise Emission ◽  
Pressure Drops ◽  
Flexible Pipes ◽  
Ansys Cfx

The growing demand for oil brings the need for discovery of deeper reservoirs, especially of ultra-deepwater reservoirs. Thus, production in marine systems using components such as risers (flexible or rigid pipes) has been the focus of many studies in different areas. These ducts are used in the transportation of multiphase fluids (oil, water and gas) produced from the oil well located on the seabed to the platform surface. Due to the extreme conditions present in the offshore fields of production, the equipments that transport produced fluids operate close to their limits. So eventually, the flexible pipes may have structural integrity faults like leaks, which can cause production losses, accidents with victims and environmental disasters. The leak depends of a number of properties or parameters measured at the site of the leak, for example, integrity of the pipe material, release of fluids and noise emission characteristics or manifestation of some other type of signal behavior, variation of pressure drops close to the leak, among others. There are a variety of techniques available for detecting leaks, among which there is the mathematical modeling approach using computational techniques. In this context, this paper aims to study the fluid dynamics of a transient multiphase flow in a catenary riser in the presence of leakage. Herein a 3D Eulerian-Eulerian model was applied, including the turbulent model (RNG k-ε), using the commercial package ANSYS CFX® 15 to perform all simulations. The numerical results of velocity, volume fraction and pressure of the involved phases are presented and discussed.

Multiphase Flow and Heat Transfer in Risers

2014 ◽  
Vol 348 ◽  
pp. 3-8 ◽  
Author(s):  
Lígia Rafaely Barbosa Sarmento ◽  
G.H.S. Pereira Filho ◽  
Antônio Gilson Barbosa de Lima ◽  
Severino Rodrigues de Farias Neto ◽  
E.S. Barbosa ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Natural Gas ◽  
Multiphase Flow ◽  
Volume Fraction ◽  
Flow Patterns ◽  
Heavy Oils ◽  
Gas Phases ◽  
Ansys Cfx ◽  
Spatial Configurations ◽  
And Control

Multiphase flows commonly occur in the production and transportation of oil, natural gas and water. In this type of flow, the phases can flow in different spatial configurations disposed inside the pipe, so called multiphase flow patterns. The identification of flow patterns and the determination of the pressure drop along the pipe lines for different volumetric flows are important parameters for management and control of production. In this sense, this work proposes to numerically investigate the non-isothermal multiphase flow of a stream of ultraviscous heavy oils containing water and natural gas in submerged risers (catenary) via numerical simulation (ANSYS CFX 11.0). Results of the pressure, volumetric fractions and temperature distributions are presented and analyzed. Numerical results show that the heat transfer was more pronounced when using the largest volume fraction of gas phases.

scholarly journals Computational-Driven Epitope Verification and Affinity Maturation of TLR4-Targeting Antibodies

2021 ◽  
Vol 22 (11) ◽  
pp. 5989
Author(s):  
Bilal Ahmad ◽  
Maria Batool ◽  
Moon Suk Kim ◽  
Sangdun Choi
Keyword(s):  
Rational Design ◽  
Structural Integrity ◽  
Critical Role ◽  
Autoimmune Encephalitis ◽  
Affinity Maturation ◽  
Antibody Binding ◽  
Computational Techniques ◽  
Multiple Strategies ◽  
Binding Epitope

Toll-like receptor (TLR) signaling plays a critical role in the induction and progression of autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematous, experimental autoimmune encephalitis, type 1 diabetes mellitus and neurodegenerative diseases. Deciphering antigen recognition by antibodies provides insights and defines the mechanism of action into the progression of immune responses. Multiple strategies, including phage display and hybridoma technologies, have been used to enhance the affinity of antibodies for their respective epitopes. Here, we investigate the TLR4 antibody-binding epitope by computational-driven approach. We demonstrate that three important residues, i.e., Y328, N329, and K349 of TLR4 antibody binding epitope identified upon in silico mutagenesis, affect not only the interaction and binding affinity of antibody but also influence the structural integrity of TLR4. Furthermore, we predict a novel epitope at the TLR4-MD2 interface which can be targeted and explored for therapeutic antibodies and small molecules. This technique provides an in-depth insight into antibody–antigen interactions at the resolution and will be beneficial for the development of new monoclonal antibodies. Computational techniques, if coupled with experimental methods, will shorten the duration of rational design and development of antibody therapeutics.

Critical Flaw Size Evaluation in Butt-Fusion Joints of HDPE Pipes

2014 ◽  
Author(s):  
S. Kalyanam ◽  
P. Krishnaswamy ◽  
E. M. Focht ◽  
D.-J. Shim ◽  
F. W. Brust ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Nuclear Industry ◽  
Flaw Size ◽  
Fusion Process ◽  
Pipe Material ◽  
Element Analysis ◽  
Hdpe Pipe ◽  
Asme Code ◽  
Critical Flaw ◽  
Pipe Joints

The integrity of high density polyethylene (HDPE) piping and fusion joints are a topic of interest to the nuclear industry, regulators, ASME code, and the plastics pipe industry. The ASME Code Case N-755-1 has been approved and addresses the use of HDPE in safety related applications. Over the last few years some of the concerns identified with the parent HDPE pipe material and the fusion joints have been addressed while others are still being resolved. One such unresolved concern is the effect of the fusion process on the integrity of the joint, specifically, the introduction of flaws during the fusion process. The potential impact of flaws in the fusion joint on the service life of the HDPE piping is being evaluated. The current study calculates stress intensity factors (SIF) for circumferential flaws and uses them to evaluate the potential structural integrity of HDPE fusion joints in pipes. The recent API 579-1/ASME FFS-1 standard provides SIF (KI) solutions to various semi-elliptical and full-circumferential (360°) surface cracks/flaws on the outer surface (OD) and the inner surface (ID). The API 579-1/ASME FFS-1 standard SIF tables and finite element analysis (FEA) of selected cases were used to develop simplified SIF relations for full-circumferential surface flaws that can be used for plastic pipes with diameters ranging from 101.6 mm (4 inch) through 914.4 mm (36 inch) and dimensional ratios (DRs) from 7 through 13. Further, the SIF of embedded flaws akin to lack-of-fusion regions was evaluated. The results from this study serve as precursors to understanding and advancing experimental methods to address important issues related to the critical tolerable flaw size in the butt-fusion joint material and were utilized to select the specimen tests and hydrostatic pipe tests used to evaluate various joining processes. Further, they will help with understanding the essential variables that control the long-term component integrity and structural performance of HDPE pipe joints in ASME Class 3 nuclear piping.

Coupled Heat and Mass Transfer CFD Model for Methane Hydrate

2015 ◽  
Author(s):  
Eugenio Turco Neto ◽  
M. A. Rahman ◽  
Syed Imtiaz ◽  
Thiago dos Santos Pereira ◽  
Fernanda Soares de Sousa
Keyword(s):  
Natural Gas ◽  
Multiphase Flow ◽  
Gas Hydrate ◽  
Gas Flow ◽  
Three Dimensional ◽  
Hydrate Formation ◽  
Cfd Model ◽  
Flow Metering ◽  
Ansys Cfx ◽  
Gas Hydrate Formation

The gas hydrates problem has been growing in offshore deep water condition where due to low temperature and high pressure hydrate formation becomes more favorable. Several studies have been done to predict the influence of gas hydrate formation in natural gas flow pipeline. However, the effects of multiphase hydrodynamic properties on hydrate formation are missing in these studies. The use of CFD to simulate gas hydrate formation can overcome this gap. In this study a computational fluid dynamics (CFD) model has been developed for mass, heat and momentum transfer for better understanding natural gas hydrate formation and its migration into the pipelines using ANSYS CFX-14. The problem considered in this study is a three-dimensional multiphase-flow model based on Simon Lo (2003) study, which considered the oil-dominant flow in a pipeline with hydrate formation around water droplets dispersed into the oil phase. The results obtained in this study will be useful in designing a multiphase flow metering and a pump to overcome the pressure drop caused by hydrate formation in multiphase petroleum production.

scholarly journals Numerical and experimental studies of gas–liquid flow and pressure drop in multiphase pump valves

2020 ◽  
Vol 103 (3) ◽  
pp. 003685042094088
Author(s):  
Yi Ma ◽  
Minjia Zhang ◽  
Huashuai Luo
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Test System ◽  
Ball Valve ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Drops ◽  
Disk Valve ◽  
Predicted Values

A numerical and experimental study was carried out to investigate the two-phase flow fields of the typical three valves used in the multiphase pumps. Under the gas volume fraction conditions in the range of 0%–100%, the three-dimensional steady and dynamic two-phase flow characteristics, pressure drops, and their multipliers of the ball valve, cone valve, and disk valve were studied, respectively, using Eulerian–Eulerian approach and dynamic grid technique in ANSYS FLUENT. In addition, a valve test system was built to verify the simulated results by the particle image velocimetry and pressure test. The flow coefficient CQ (about 0.989) of the disk valve is greater than those of the other valves (about 0.864) under the steady flow with a high Reynolds number. The two-phase pressure drops of the three valves fluctuate in different forms with the vibration of the cores during the dynamic opening. The two-phase multipliers of the fully opened ball valve are consistent with the predicted values of the Morris model, while those of the cone valve and disk valve had the smallest differences with the predicted values of the Chisholm model. Through the comprehensive analysis of the flow performance, pressure drop, and dynamic stability of the three pump valves, the disk valve is found to be more suitable for the multiphase pumps due to its smaller axial space, resistance loss, and better flow capacity.

Numerical Simulation of Cavitating Flow in a Globe Valve: Comparison of OpenFoam and CFX

2016 ◽  
Author(s):  
Daniel Rodriguez Calvete ◽  
Anne Gosset ◽  
Daniel Pierrat ◽  
Anthony Couzinet
Keyword(s):  
Cavitating Flows ◽  
Cavitation Model ◽  
Pressure Drops ◽  
Control Valves ◽  
Ansys Cfx ◽  
Large Pressure ◽  
Equilibrium Approach ◽  
Service Control ◽  
Globe Valve ◽  
Subsequent Modification

The efficiency of control valves operating with liquids is highly conditioned by the occurrence of cavitation when they undergo large pressure drops. For severe service control valves, the subsequent modification of their performance can be crucial for the safety of an installation. In this work, two CFD codes, OpenFoam [1] and Ansys-CFX, are used to characterize the flow in a globe valve, with the objective to compare their capabilities in solving cavitating flows in complex 3D geometries. In both codes, an Homogeneous Equilibrium approach is adopted, and phase change is modeled with a similar cavitation model. It is found that both solvers predict correctly the location of vapor cavities, but tend to underestimate their extension. The flow rate is correctly calculated, but in strong cavitating regimes, it is affected by the underprediction of vapor cavities. The force acting on the stem is found to be more sensitive to the computation parameters.

Multiphase Flow Measurement System of Oil Well

2007 ◽  
Author(s):  
Zhiyao Huang ◽  
Chaohong He ◽  
Qilin Liang
Keyword(s):  
Multiphase Flow ◽  
Measurement System ◽  
Flow Measurement ◽  
Oil Well

Parametric Investigation on the Effect Factors for Liquid Droplet Impingement Erosion

2011 ◽  
Author(s):  
Rui Li ◽  
Hisashi Ninokata ◽  
Michitsugu Mori
Keyword(s):  
Power Plants ◽  
Erosion Rate ◽  
Structural Integrity ◽  
Volume Fraction ◽  
Liquid Droplet ◽  
Droplet Velocity ◽  
Life Extension ◽  
Droplet Impingement ◽  
Pipe Surface ◽  
Bent Pipe

Liquid droplet impingement (LDI) erosion could be regarded to be one of the major causes of unexpected troubles occasionally occurred in the inner bent pipe surface. Evaluating the LDI erosion is an important topic of the thermal hydraulics and structural integrity in aging and life extension for nuclear power plants safety. In order to investigate the effect of various parameters, such as droplet diameter, droplet velocity and injected droplet number, on the erosion rate induced by LDI, droplet impingement under different conditions are conducted numerically by a two-phase computational approach. Considering the carrier turbulence kinetic energy attenuation due to the involved droplets, numerical simulations have been performed by using two-way vapor-droplet coupled system. This computational fluid model is built up by incompressible Reynolds Averaged Navier-Stoke equations using standard k-ε model and the SIMPLE algorithm, and the numerical droplet model adopts the Lagrangian approach, a general LDI erosion prediction procedure for bent pipe geometry has been performed to supplement an available CFD code. A correlation for the erosion rate in terms of droplet velocity, diameter and volume fraction is purposed for the engineers’ maintenance reference. Based on our computational results, comparison with an available accident data was made to prove that our methodology could be an appropriate way to simulate and predict the bent pipe wall thinning phenomena.

A NEW RELATIVE PERMEABILITY MODEL OF UNSATURATED POROUS MEDIA BASED ON FRACTAL THEORY

Fractals ◽  
2020 ◽  
Vol 28 (01) ◽  
pp. 2050002
Author(s):  
KE CHEN ◽  
HE CHEN ◽  
PENG XU
Keyword(s):  
Experimental Data ◽  
Porous Media ◽  
Fractal Dimension ◽  
Multiphase Flow ◽  
Relative Permeability ◽  
Volume Fraction ◽  
Fractal Model ◽  
Accurate Estimation ◽  
Unsaturated Porous Media ◽  
Flow Through

The multiphase flow through unsaturated porous media and accurate estimation of relative permeability are significant for oil and gas reservoir, grounder water resource and chemical engineering, etc. A new fractal model is developed for the multiphase flow through unsaturated porous media, where multiscale pore structure is characterized by fractal scaling law and the trapped water in the pores is taken into account. And the analytical expression for relative permeability is derived accordingly. The relationships between the relative permeability and capillary head as well as saturation are determined. The proposed model is validated by comparison with 14 sets of experimental data, which indicates that the fractal model agrees well with experimental data. It has been found that the proposed fractal model shows evident advantages compared with BC-B model and VG-M model, especially for the porous media with fine content and texture. Further calculations show that water permeability decreases as the fractal dimension increases under fixed saturation because the cumulative volume fraction of small pores increases with the increment of the fractal dimension. The present fractal model for the relative permeability may be helpful to understand the multiphase flow through unsaturated porous media.

A Numerical Investigation of Nanofluids Thermal Behavior in Microchannels Under Laminar Flow Conditions

2015 ◽  
Author(s):  
I. P. Koronaki ◽  
M. T. Nitsas ◽  
Ch. A. Vallianos
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Laminar Flow ◽  
Volume Fraction ◽  
Constant Heat Flux ◽  
Flow Conditions ◽  
New Techniques ◽  
Pressure Drops ◽  
Nanoparticles Volume Fraction ◽  
The Heat Transfer Coefficient

Due to large amounts of heat flux developed in electronic devices, it is essential to propose and investigate effective mechanisms of cooling them. Although microchannels filled with flowing coolant are a geometry often met in such devices, new techniques need to be developed in order to increase their effectiveness. Recent studies on nanofluids, i.e. mixtures of nanometer size particles well-dispersed in a base fluid, have demonstrated their potential for augmenting heat transfer. In the present work the 2D steady state laminar flow of different nanofluids along a microchannel is examined. It is considered that the microchannel walls receive uniform and constant heat flux. The problem’s modelling has as parameters the volume fraction of nanoparticles ranging from 0 to 5% and Reynolds number varying between 50 and 500. The results of the problem’s numerical solution are used to calculate the heat transfer coefficient, the pressure drop along the microchannel and the destroyed exergy. It is found that heat transfer is enhanced due to the presence of nanoparticles. On the contrary, pressure drops faster due to nanofluids increased viscosity leading to more pump power needed. Finally, further exergy destruction is observed when nanoparticles volume fraction increases.

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