Experimental and Numerical Assessment of Both Slug and Vortex Induced Vibrations on a Spool Model

2020 ◽  
Author(s):  
Matthieu Minguez ◽  
Kevin Le Prin ◽  
Alain Liné ◽  
Vincent Lafon ◽  
François Pétrié ◽  
...  
Keyword(s):  
Slug Flow ◽  
Mechanical Response ◽  
Numerical Models ◽  
Induced Response ◽  
Flow Properties ◽  
External Excitation ◽  
Mechanical Responses ◽  
Vortex Induced Vibrations ◽  
Numerical Assessment ◽  
Slug Flows

Abstract The paper addresses the flow-induced response of a rigid spool/jumper. It mainly focuses on its mechanical response resulting from internal intermittent slug flows but also addresses potential coupling with an external excitation due to vortex shedding. These works provide quantitative experimental data that match quite well with existing empirical correlations in terms of slug flow properties. The repeatability of the measurement system has been experienced and underlines promising capabilities. The tests provide exhaustive complementary data regarding the slug flow properties (e.g. pocket length) which will be reused for numerical modelling purpose. The mechanical response of the spool is exhaustively addressed for different regular slug flows. Some correlations are proposed aiming at describing the mechanical responses. The coupling with an additional external current solicitation and Vortex Induced Vibrations (VIV) is discussed and characterized for some conditions. Finally, a discussion on the current Industry Best Practices is introduced in order to challenge the capability of the proposed approaches to described and recover such complex phenomenon. The comparisons underline the weak agreement between experiments and numerical models, opening discussion on the best way to address this physics and the next developments.

scholarly journals Evolution of Meniscal Biomechanical Properties with Growth: An Experimental and Numerical Study

2021 ◽  
Vol 8 (5) ◽  
pp. 70
Author(s):  
Marco Ferroni ◽  
Beatrice Belgio ◽  
Giuseppe M. Peretti ◽  
Alessia Di Giancamillo ◽  
Federica Boschetti
Keyword(s):  
Mechanical Properties ◽  
Stress Relaxation ◽  
Developmental Stage ◽  
Mechanical Response ◽  
Numerical Study ◽  
Numerical Models ◽  
Mechanical Stimulus ◽  
Specific Response ◽  
Mechanical Parameters ◽  
Biochemical Analyses

The menisci of the knee are complex fibro-cartilaginous tissues that play important roles in load bearing, shock absorption, joint lubrication, and stabilization. The objective of this study was to evaluate the interaction between the different meniscal tissue components (i.e., the solid matrix constituents and the fluid phase) and the mechanical response according to the developmental stage of the tissue. Menisci derived from partially and fully developed pigs were analyzed. We carried out biochemical analyses to quantify glycosaminoglycan (GAG) and DNA content according to the developmental stage. These values were related to tissue mechanical properties that were measured in vitro by performing compression and tension tests on meniscal specimens. Both compression and tension protocols consisted of multi-ramp stress–relaxation tests comprised of increasing strains followed by stress–relaxation to equilibrium. To better understand the mechanical response to different directions of mechanical stimulus and to relate it to the tissue structural composition and development, we performed numerical simulations that implemented different constitutive models (poro-elasticity, viscoelasticity, transversal isotropy, or combinations of the above) using the commercial software COMSOL Multiphysics. The numerical models also allowed us to determine several mechanical parameters that cannot be directly measured by experimental tests. The results of our investigation showed that the meniscus is a non-linear, anisotropic, non-homogeneous material: mechanical parameters increase with strain, depend on the direction of load, and vary among regions (anterior, central, and posterior). Preliminary numerical results showed the predominant role of the different tissue components depending on the mechanical stimulus. The outcomes of biochemical analyses related to mechanical properties confirmed the findings of the numerical models, suggesting a specific response of meniscal cells to the regional mechanical stimuli in the knee joint. During maturation, the increase in compressive moduli could be explained by cell differentiation from fibroblasts to metabolically active chondrocytes, as indicated by the found increase in GAG/DNA ratio. The changes of tensile mechanical response during development could be related to collagen II accumulation during growth. This study provides new information on the changes of tissue structural components during maturation and the relationship between tissue composition and mechanical response.

3-D Numerical Simulations of Subsea Jumper Transporting Intermittent Slug Flows

2018 ◽  
Author(s):  
Jihyeon Kim ◽  
Narakorn Srinil
Keyword(s):  
Slug Flow ◽  
Oil And Gas ◽  
Process Condition ◽  
Structural Response ◽  
Dynamic Responses ◽  
Operating Pressure ◽  
Computational Performance ◽  
Fluid Properties ◽  
Slug Flows ◽  
Interaction Approach

Subsea jumper is the steel pipe structure to connect wellhead and subsea facilities such as manifolds or processing units in order to transport the produced multiphase flows. Generally, the jumper consists of a goalpost with two loop structures and a straight pipe between them, carrying the multiphase oil and gas from the producing well. Due to the jumper pipe characteristic geometry and multi-fluid properties, slug flows may take place, creating problematic fluctuating forces causing the jumper oscillations. Severe dynamic fluctuations cause the risk of pipe deformations and resonances resulting from the hydrodynamic momentum/pressure forces which can lead to unstable operating pressure and decreased production rate. Despite the necessity to design subsea jumper with precise prediction on the process condition and the awareness of slug flow risks, it is challenging to experimentally evaluate, identify and improve the modified design in terms of the facility scale, time and cost efficiency. With increasing high computational performance, numerical analysis provides an alternative approach to simulate multiphase flow-induced force effects on the jumper. The present paper discusses the modelling of 3-D flow simulations in a subsea jumper for understanding the development process of internal slug flows causing hydrodynamic forces acting on the pipe walls and bends. Based on the fluctuating pressure calculated by the fluid solver, dynamic responses of the jumper pipe are assessed by a one-way interaction approach to evaluate deformation and stress. A potential resonance is discussed with the jumper modal analysis. Results from the structural response analyses show dominant multi-modal frequencies due to intermittent slug flow frequencies. Numerical results and observed behaviors may be useful for a comparison with other simulation and experiment.

Application of a General Technique for Prediction of Riser Vortex-Induced Response in Waves and Current

1989 ◽  
Vol 111 (2) ◽  
pp. 82-91 ◽  
Author(s):  
G. J. Lyons ◽  
M. H. Patel
Keyword(s):  
Time Domain ◽  
Calculation Method ◽  
Prediction Method ◽  
Induced Response ◽  
Flow Properties ◽  
General Technique ◽  
Prediction Technique ◽  
Combined Action ◽  
Semi Empirical ◽  
Surface Vessel

This paper describes applications of an extension to a recently developed calculation method for vortex-induced response of risers and tethers. The vortex-induced vibration response for the excited modes is generated using a semi-empirical formulation which is applied within a time domain calculation. This makes it possible to take account of the variation of flow properties along the riser length, as well as in time. The calculation method has been verified by comparison with model test data for vortex-induced response to surface vessel motions in still water. This paper presents applications of the technique for vortex shedding due to the combined action of current, surface vessel motions and waves. The mathematics of the extended prediction technique is described and results are illustrated by presenting typical vortex-induced responses for single-tube risers. The results of the prediction method are used to highlight the relative magnitudes and nature of vortex-induced response excited by currents, surface vessel motions and waves.

scholarly journals Understanding the effects of beetroot juice intake on CrossFit performance by assessing hormonal, metabolic and mechanical response: a randomized, double-blind, crossover design

2020 ◽  
Author(s):  
Manuel V. Garnacho-Castaño ◽  
Guillem Palau-Salvà ◽  
Noemí Serra-Payá ◽  
Mario Ruiz-Hermosel ◽  
Marina Berbell ◽  
...  
Keyword(s):  
Oxygen Saturation ◽  
Interaction Effect ◽  
Mechanical Response ◽  
Crossover Design ◽  
Muscular Fatigue ◽  
Anaerobic Performance ◽  
Beetroot Juice ◽  
Double Blind ◽  
Mechanical Responses ◽  
Bonferroni Test

Abstract Background: Acute beetroot juice (BJ) intake has shown to enhance aerobic and anaerobic performance. However, no studies have evaluated the effects of BJ intake on CrossFit (CF) performance by linking hormonal, metabolic, and mechanical responses. The purpose of this study was to determine the causal physiological association between hormonal, metabolic and mechanical responses, and CF workouts performance after acute BJ intake. Methods: Twelve well-trained male practitioners undertook a CF workout after drinking 140 mL of BJ (~ 12.8 mmol NO3−) or placebo. The two experimental conditions (BJ or placebo) were administered using a randomized, double-blind, crossover design. The CF workout consisted of repeating the same exercise routine twice: Wall ball (WB) shots plus full back squat (FBS) with 3-min rest (1st routine) or without rest (2nd routine) between the two exercises. A 3-min rest was established between the two exercise routines.Results: An interaction effect was observed in the number of repetitions performed (p = 0.04). The Bonferroni test determined a higher number of repetitions after BJ than placebo intake when a 3-min rest between WB and FBS (1st routine) was established (p = 0.007). An interaction effect was detected in cortisol response (p = 0.04). Cortisol showed a higher increase after BJ compared to placebo intake (76% vs. 36%, respectively). No interaction effect was observed in the testosterone and testosterone/cortisol ratio (p > 0.05). A significant interaction effect was found in oxygen saturation (p = 0.01). A greater oxygen saturation drop was observed in BJ compared to placebo (p < 0.05). An interaction effect was verified in muscular fatigue (p = 0.03) with a higher muscular fatigue being observed with BJ than placebo (p = 0.02). Conclusions: BJ intake improved anaerobic performance only after the recovery time between exercises. This increase in performance in the first routine probably generated greater hypoxia in the muscle mass involved, possibly conditioning post-exercise performance. This was observed with a fall in oxygen saturation and in muscle fatigue measured at the end of the CF workout. The greatest perceived changes in cortisol levels after BJ intake could be attributed to the nitrate-nitrite-nitric oxide pathway

scholarly journals Combined numerical and experimental study of microstructure and permeability in porous granular media

2020 ◽  
Author(s):  
Philipp Eichheimer ◽  
Marcel Thielmann ◽  
Wakana Fujita ◽  
Gregor J. Golabek ◽  
Michihiko Nakamura ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Numerical Simulations ◽  
Granular Media ◽  
Large Scale ◽  
Earth Science ◽  
Numerical Models ◽  
Effective Porosity ◽  
Flow Properties ◽  
Wide Range ◽  
Flow Through

Abstract. Fluid flow on different scales is of interest for several Earth science disciplines like petrophysics, hydrogeology and volcanology. To parameterize fluid flow in large-scale numerical simulations (e.g. groundwater and volcanic systems), flow properties on the microscale need to be considered. For this purpose experimental and numerical investigations of flow through porous media over a wide range of porosities are necessary. In the present study we sinter glass bead media with various porosities. The microstructure, namely effective porosity and effective specific surface, is investigated using image processing. We determine flow properties like hydraulic tortuosity and permeability using both experimental measurements and numerical simulations. By fitting microstructural and flow properties to porosity, we obtain a modified Kozeny-Carman equation for isotropic low-porosity media, that can be used to simulate permeability in large-scale numerical models. To verify the modified Kozeny-Carman equation we compare it to the computed and measured permeability values.

Investigations on Slug Flow in a Horizontal Pipe Using Stereoscopic Particle Image Velocimetry and CFD Simulation With Volume of Fluid Method

2012 ◽  
Author(s):  
Marek Czapp ◽  
Matthias Utschick ◽  
Johannes Rutzmoser ◽  
Thomas Sattelmayer
Keyword(s):  
Particle Image Velocimetry ◽  
Slug Flow ◽  
Particle Image ◽  
Volume Of Fluid ◽  
Stereoscopic Particle Image Velocimetry ◽  
Horizontal Pipe ◽  
Pressurized Water ◽  
Cooling Circuit ◽  
Image Velocimetry ◽  
Slug Flows

Investigations on gas-liquid flows in horizontal pipes are of immanent importance for Reactor Safety Research. In case of a breakage of the main cooling circuit of a Pressurized Water Reactor (PWR), the pressure losses of the gas-liquid flow significantly govern the loss of coolant rate. The flow regime is largely determined by liquid and gas superficial velocities and contains slug flow that causes high-pressure pulsations to the infrastructure of the main cooling circuit. Experimental and numerical investigations on adiabatic slug flow of a water-air system were carried out in a horizontal pipe of about 10 m length and 54 mm diameter at atmospheric pressure and room temperature. Stereoscopic high-speed Particle Image Velocimetry in combination with Laser Induced Fluorescence was successfully applied on round pipe geometry to determine instantaneous three-dimensional water velocity fields of slug flows. After grid independence studies, numerical simulations were run with the open-source CFD program OpenFOAM. The solver uses the VOF method (Volume of Fluid) with phase-fraction interface capturing approach based on interface compression. It provides mesh refinement at the interfacial area to improve resolution of the interface between the two phases. Furthermore, standard k-ε turbulence model was applied in an unsteady Reynolds averaged Navier Stokes (URANS) model to resolve self-induced slug formation. The aim of this work is to present the feasibility of both relatively novel possibilities of determining two-phase slug flows in pipes. Experimental and numerical results allow the comparison of the slug initiation and expansion process with respect to their axial velocities and cross-sectional void fractions.

scholarly journals INELASTIC RESPONSES OF SWOLLEN NITRILE RUBBER UNDER CYCLIC LOADING

2018 ◽  
Vol 91 (1) ◽  
pp. 136-150 ◽  
Author(s):  
Mei Sze Loo ◽  
Jean Benoît Le Cam ◽  
Andri Andriyana ◽  
Eric Robin
Keyword(s):  
Cyclic Loading ◽  
Mechanical Response ◽  
Mechanical Responses ◽  
Material Compatibility ◽  
Durability Analysis ◽  
Inelastic Responses ◽  
Nitrile Rubbers ◽  
Loading Tests ◽  
Cyclic Loading Tests ◽  
Conventional Diesel Fuel

ABSTRACT Palm biodiesel is deemed a promising future fuel substitute for conventional diesel fuel. In line with this perspective, necessary changes in the existing diesel engine system are expected in order to address the issue of material compatibility. One typical degradation observed in rubber components exposed to aggressive solvent such as palm biodiesel during the service is swelling. Thus, the investigation of the effect of swelling on the mechanical response under cyclic loading is prerequisite for durability analysis of such components. In this study, filled and unfilled swollen nitrile rubbers are immersed in conventional diesel and palm biodiesel baths until a 5% swelling level is achieved. Both dry and swollen rubbers are subjected to uniaxial cyclic loading tests. The analysis of the mechanical responses has shown that swelling decreases inelastic effects such as hysteresis, stress softening, and permanent set. For both dry and swollen rubbers, fillers are found to have significant effects in the inelastic responses, whereas the effects of solvent and loading rate are comparable.

A Study of the Strain Response of Stainless Steel 304 to Extreme Uniform Instantaneous Explosion Pressure Loads

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Geraint O. Thomas ◽  
Gwyn L. Oakley
Keyword(s):  
Stainless Steel ◽  
Mechanical Response ◽  
Gaseous Detonation ◽  
Explosion Pressure ◽  
Mechanical Responses ◽  
Physical Measurements ◽  
Linear Relationships ◽  
Stainless Steel 304 ◽  
Series Of Experiments ◽  
Universal Correlation

Abstract The paper describes a new configuration using a gaseous detonation explosive blast source suitable for the studies of the instantaneous uniform pressure loading and mechanical response of materials. The capabilities of the configuration are illustrated by a preliminary series of experiments of the dynamic loading of clamped circular plates of 304 grade stainless steel with thicknesses ranging from 9.5 mm to 0.5 mm. The mechanical responses of the plates were monitored using strain gauges placed across the plate radius together with physical measurements of any permanent residual displacement of the center of the plate. The residual central deformations were analyzed using a well-established correlation involving nondimensional pressure load impulse. No universal correlation for the present data was found, but linear relationships for changes in two experimental parameters were identified, suggesting that the existing correlations have some deficiencies when applied to stainless steel 304.

scholarly journals Mode-I Fracture Behavior of CFRPs: Numerical Model of the Experimental Results

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 513 ◽  
Author(s):  
Claudia Barile ◽  
Caterina Casavola ◽  
Benedetto Gambino ◽  
Alessandro Mellone ◽  
Marco Spagnolo
Keyword(s):  
Numerical Model ◽  
Composite Laminates ◽  
High Performance ◽  
Mechanical Response ◽  
Numerical Models ◽  
Constitutive Relationship ◽  
Mode I ◽  
Experimental Calibration ◽  
Reinforced Plastics ◽  
High Performance Composite

In the last decades, the increasing use of laminate materials, such as carbon fibre reinforced plastics, in several engineering applications has pushed researchers to deeply investigate their mechanical behavior, especially in consideration of the delamination process, which could affect their performance. The need for improving the capability of the current instruments in predicting some collapse or strength reduction due to hidden damages leads to the necessity to combine numerical models with experimental campaigns. The validation of the numerical models could give useful information about the mechanical response of the materials, providing predictive data about their lifetime. The purpose of the delamination tests is to collect reliable results by monitoring the delamination growth of the simulated in situ cracking and use them to validate the numerical models. In this work, an experimental campaign was carried out on high performance composite laminates with respect to the delamination mode I; subsequently, a numerical model representative of the experimental setup was built. The ANSYS Workbench Suite was used to simulate the delamination phenomena and modeFRONTIER was applied for the numerical/experimental calibration of the constitutive relationship on the basis of the delamination process, whose mechanism was implemented by means of the cohesive zone material (CZM) model.

Dynamic Characteristics of Deep-Water Risers Carrying Multiphase Flows

2018 ◽  
Author(s):  
Bowen Ma ◽  
Narakorn Srinil
Keyword(s):  
Steady State ◽  
Free Vibration ◽  
Multiphase Flow ◽  
Deep Water ◽  
Slug Flow ◽  
Internal Dynamic ◽  
Gas Flows ◽  
Time Space ◽  
Slug Flows ◽  
Oscillation Frequencies

Deep-water flexible risers conveying hydrocarbon oil and gas flows may be subject to internal dynamic fluctuations associated with the spatial variations of phase densities, velocities and pressure drops. Many studies have focused on single-phase flows in pipes whereas understanding of multiphase flow effects is lacking. This study aims to investigate the planar free-vibration characteristics of a long flexible catenary riser carrying the steady-state, multiphase slug oil-gas flows in order to understand how the inclination-dependent internal slug flows affect riser natural frequencies and modal shapes. The influence of slug characteristics such as phase velocities on the riser vibration is also studied. The catenary riser planar motions are mathematically described by a two-dimensional continuum model capturing coupled horizontal and vertical responses. Based on the selected two-phase flow rates at the wellhead, riser geometric configurations and specified slug unit lengths, a steady-state slug flow model is considered by taking into account several empirical closure correlations and riser mechanical properties, solving for the multiphase flow aspects including pressure, velocities, liquid holdup and gas fraction. By assigning an undamped free-vibration shape of an empty catenary riser as initial displacement conditions, the space-time numerical simulations are performed using a finite difference approach. Comparisons of oscillation frequencies, time histories, phase planes, time-space varying responses and dynamic stresses of catenary risers with and without slug flows are presented, identifying the dynamic modifications arising from the internal slug-induced mass momentum change and pressure loss. To understand the influence of slug flow properties, parametric studies are carried out with different gas velocities. Numerical results highlight the reduced riser tensions, decreased oscillation frequencies, multiple oscillation modes, amplified amplitudes and stresses. These key observations will be useful for the forced vibration analysis of catenary risers subject to combined internal (multiphase) and external (vortex-shedding) flow excitations.

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