3-D Transient CFD Modeling of Pig Motion

2016 ◽  
Author(s):  
Diego Jaimes Parilli ◽  
Nelson Loaiza ◽  
Janneth García ◽  
Armando Blanco
Keyword(s):  
Pressure Drop ◽  
Numerical Models ◽  
Control Volume ◽  
Physical Models ◽  
Body Motion ◽  
Cfd Modeling ◽  
Maximum Pressure ◽  
Variable Boundary ◽  
Numerical Predictions ◽  
Wide Range

Pigging operations are common procedures for pipeline maintenance. However, questions still remain about pig dynamics due to the difficulties to accurately describe this complex phenomenon. Consequently, most predictions of pig dynamics are based on empirical knowledge deduced from experimental data and numerical models developed considering simplified physical models, without calculate transient pig-flow interaction and neglecting 3D aspect of flow dynamics. Therefore, to present an actual 3D transient model, this paper proposes a novel CFD methodology using a static mesh in a moving control volume. Forces acting on the pig are dynamically computed by a Fluid-Structure Interaction (FSI) approach; pig velocity is obtained for each time instant and it is set as a variable boundary condition. This method was validated with experimental results and it may be used to describe a wide range of rigid body motion immerse in a flow. This approach is then utilized to obtain the transient simulation of a pig launch in a straight water pipeline. Numerical predictions of the static grid method were compared with those obtained using moving mesh simulations. Results show that the pig reaches a terminal velocity higher than average flow velocity and a huge difference on predictions of maximum pressure drop (through the pig) between steady state based models and transient models. Additionally, it was simulated a 2D model to observe the differences between 2D and 3D simulations on the flow characteristics and pig motion features, which shows an important increase of the pressure drop on 3D model over 2D and high pig acceleration in the 3D simulation.

scholarly journals Two-Dimensional Numerical Modeling of Flow in Physical Models of Rock Vane and Bendway Weir Configurations

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 458
Author(s):  
Drew C. Baird ◽  
Benjamin Abban ◽  
S. Michael Scurlock ◽  
Steven B. Abt ◽  
Christopher I. Thornton
Keyword(s):  
Numerical Modeling ◽  
Physical Model ◽  
Numerical Models ◽  
Hydraulic Performance ◽  
Physical Models ◽  
Protection Measures ◽  
Design Engineers ◽  
Model Study ◽  
Study Results ◽  
Wide Range

While there are a wide range of design recommendations for using rock vanes and bendway weirs as streambank protection measures, no comprehensive, standard approach is currently available for design engineers to evaluate their hydraulic performance before construction. This study investigates using 2D numerical modeling as an option for predicting the hydraulic performance of rock vane and bendway weir structure designs for streambank protection. We used the Sedimentation and River Hydraulics (SRH)-2D depth-averaged numerical model to simulate flows around rock vane and bendway weir installations that were previously examined as part of a physical model study and that had water surface elevation and velocity observations. Overall, SRH-2D predicted the same general flow patterns as the physical model, but over- and underpredicted the flow velocity in some areas. These over- and underpredictions could be primarily attributed to the assumption of negligible vertical velocities. Nonetheless, the point differences between the predicted and observed velocities generally ranged from 15 to 25%, with some exceptions. The results showed that 2D numerical models could provide adequate insight into the hydraulic performance of rock vanes and bendway weirs. Accordingly, design guidance and implications of the study results are presented for design engineers.

Finite element modelling for orthogonal machining of AA2024-T351 alloy with an advanced fracture criterion

2021 ◽  
pp. 1-41
Author(s):  
Prudvi Reddy Paresi ◽  
N. Arunachalam ◽  
Yanshan Lou ◽  
Jeong Whan Yoon
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
High Speed ◽  
Fracture Criterion ◽  
Numerical Models ◽  
Machining Simulation ◽  
Experimental Conditions ◽  
Orthogonal Machining ◽  
Numerical Predictions ◽  
Wide Range

Abstract Numerical modelling of the plastic deformation and fracture during the high speed machining is highly challengeable. Consequently, there is a need for an advanced constitutive model and fracture criterion to make the numerical models more reliable. The aim of the present study is to extend the recent advanced static Lou-Yoon-Huh (LYH) ductile fracture creation to high strain rate and temperature applications such as machining. In the present work, the LYH static fracture creation was extended to machining conditions by introducing strain rate and temperature dependency terms. This extended LYH fracture criterion was calibrated over the wide range of stress triaxialities and different temperatures. Modified Khan- Huang-Liang (KHL) constitutive model along with the variable friction model was employed to predict the flow behaviour of work material during the machining simulation. Damage evolution method was coupled to identify the element deletion point during the machining simulation. Orthogonal machining experiments were carried out for an aerospace grade AA2024-T351 at cutting speeds varying between 100 and 400m/min with the feed rates varying between 0.1 and 0.3mm/rev. To assess the prediction capabilities of extended LYH fracture criterion numerical simulations were also carried out using Johnson-Cook (JC) fracture criterion under all experimental conditions. Specific cutting energy, chip morphology and compression ratio predictions were compared with the experimental data. Numerical predictions with coupled extended LYH criterion showed good agreement with experimental results compared to coupled JC fracture criterion.

Influence of PIG Mass, Launching Time and Turbulence Model on 3-D CFD Transient Simulation of PIG Motion

2016 ◽  
Author(s):  
Diego Jaimes Parilli ◽  
Armando Blanco ◽  
Janneth García
Keyword(s):  
Pressure Drop ◽  
Numerical Models ◽  
Control Volume ◽  
Asymptotic Relation ◽  
Fluid Pressure ◽  
Turbulence Models ◽  
Transient State ◽  
Terminal Velocity ◽  
Transient Simulation ◽  
Transient Pressure

Pigging procedures are common maintenance operations used to perform cleaning, draining and pipeline inspection in order to improve flow efficiency and operation cost. Despite these procedures are commonly used, questions still remain regarding the flow and the PIG motion features due to the complex interaction among pig, wall and flow, and the changes in internal fluid pressure and local fluid density. Currently, the PIG dynamic predictions are based on experimental data from short scale laboratory experiments and numerical models founded on physical simplification. So far, the transient of PIG motion calculated by methods that combine CFD and fluid-structure interaction in a 3D model and the influence of the physic and numerical features over the pig dynamics has not been analyzed yet. To provide a better understanding of pigging runs, this paper proposes a CFD methodology to obtain a 3D transient simulation of PIG motion. A moving control volume attached to the PIG let to solve the governing equation in a stationary mesh. This methodology is used to obtain the transient simulation of a PIG launched in a straight water pipeline for different PIG mass, launching time and turbulence models in order to study its influence over the PIG dynamics. The numerical results show a linear relation between the mass and the pressure drop in the transient state, but with no influence over the final stationary state. Also, an asymptotic relation between the transient pressure drop and the launching time was observed with no influence over the PIG terminal velocity. Besides, it is exposed the influence of the turbulence models (κ-ε, SST and BSL Reynolds Stress) in the results of pig motion; appreciable difference between the drop pressure of Omega-Based Stress Models (SST and BSL) and κ-ε turbulent model at steady state is shown, and, finally, a comparison of the velocity profiles at the interstice for each model was developed, this one shows an inaccuracy of the κ-ε model to describe the velocity profile in the walls proximities.

scholarly journals The Effect of Spool Displacement Control to the Flow Rate in the Piezoelectric Stack-Based Valve System Subjected to High Operating Temperature

Actuators ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 239
Author(s):  
Yu-Jin Park ◽  
Bo-Gyu Kim ◽  
Jun-Cheol Jeon ◽  
Dongsoo Jung ◽  
Seung-Bok Choi
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Operating Temperature ◽  
Control Volume ◽  
Tracking Error ◽  
Displacement Control ◽  
Structural Part ◽  
Valve System ◽  
Wide Range ◽  
Experimental Apparatus

This work investigates the effect of spool displacement control of the piezoelectric stack actuator (PSA) based valve system on the flow motion of the pressure drop and flow rate. As a first step, the governing equations of the structural parts of the displacement amplifier and spool are derived, followed by the governing equation of the fluid part considering control volume and steady flow force. Then, an appropriate size of the valve is designed and manufactured. An experimental apparatus to control the spool displacement is set up in the heat chamber and tracking control for the spool displacement is evaluated at 20 °C and 100 °C by implementing a proportional-integral-derivative (PID) feedback controller. The tracking controls of the spool displacement associated with the sinusoidal and triangular trajectories are realized at 20 °C and 100 °C. It is demonstrated that the tracking controls for the sinusoidal and triangular trajectories have been well carried out showing the tracking error less than 3 μm at both temperatures. In addition, the flow motions for the pressure drop and the flow rate of the proposed valve system are experimentally investigated. It is identified from this investigation that both pressure drop and flow rate evaluated 20 °C have been decreased up to 18% at 100 °C. This result directly indicates that the temperature effect to control performance of the structural part and fluid part in the proposed PSA based valve system is different and hence careful attention is required to achieve the successful development of advanced valve systems subjected to a wide range of the operating temperature.

scholarly journals Accuracy of boundary layer treatments at different Reynolds scales

2020 ◽  
Vol 10 (1) ◽  
pp. 295-310
Author(s):  
Nicolás D. Badano ◽  
Angel N. Menéndez
Keyword(s):  
Scale Effects ◽  
Numerical Models ◽  
Physical Models ◽  
Wall Friction ◽  
Navier Stokes ◽  
Parallel Plates ◽  
Scale Free ◽  
Head Losses ◽  
Wide Range ◽  
Resistive Forces

AbstractResistive forces associated to boundary layers (‘friction’) are usually out of scale in physical models of hydraulic structures, especially in the case of hydraulically smooth walls, generating distortions in the model results known as scale effects, that can be problematic in some relevant engineering problems. These scale effects can be quantified and corrected using suitable numerical models. In this paper the accuracy of using numerical simulation through the Reynolds Averaged Navier-Stokes (RANS) approximation in order to represent the head losses introduced by friction in hydraulically smooth walls is evaluated for a wide range of Reynolds scales. This is performed by comparing the numerical results for fully developed flow on circular pipes and between parallel plates against experimental results, using the most popular wall treatments. The associated numerical errors, mesh requirements and ranges of application are established for each treatment. It is shown that, when properly applied, RANS models are able to simulate the head losses produced by smooth wall friction accurately enough as to quantify the scale effects present in physical models. A methodology for upscaling physical model results to prototype scale, free of scale effects, is proposed.

scholarly journals Marine Turbine Hydrodynamics by a Boundary Element Method with Viscous Flow Correction

2018 ◽  
Author(s):  
Francesco Salvatore ◽  
Zohreh Sarichloo ◽  
Danilo Calcagni
Keyword(s):  
Viscous Flow ◽  
Numerical Models ◽  
Turbine Blades ◽  
Integral Equation Method ◽  
Boundary Integral ◽  
Operating Conditions ◽  
Hydrodynamic Performance ◽  
Numerical Predictions ◽  
Wide Range ◽  
Marine Current

A computational methodology for the hydrodynamic analysis of horizontal axis marine current turbines is presented. The approach is based on a boundary integral equation method for inviscid flows originally developed for marine propellers and adapted here to describe the flow features that characterize hydrokinetic turbines. To this purpose, semi-analytical trailing wake and viscous-flow correction models are introduced. A validation study is performed by comparing hydrodynamic performance predictions with two experimental test cases and with results from other numerical models in the literature. The capability of the proposed methodology to correctly describe turbine thrust and power over a wide range of operating conditions is discussed. Viscosity effects associated to blade flow separation and stall are taken into account and predicted thrust and power are comparable with results of blade element methods that are largely used in the design of marine current turbines. The accuracy of numerical predictions tend to reduce in cases where turbine blades operate in off-design conditions.

VERY DEEP FACILITIES PHYSICAL MODELLING STRATEGIES

1998 ◽  
Vol 38 (1) ◽  
pp. 594
Author(s):  
J B. Hinwood ◽  
A.E. Potts ◽  
P. Sincock
Keyword(s):  
Design Process ◽  
Numerical Models ◽  
Physical Modelling ◽  
Physical Models ◽  
Dynamic Responses ◽  
Laboratory Facilities ◽  
Wide Range ◽  
Final Design ◽  
Modelling Strategies ◽  
Hull Forms

The design process for offshore facilities has used a mix of physical and numerical modelling to provide information on loads and steady dynamic responses in an efficient and accurate fashion. Usually physical modelling is used early in the design process to provide force coefficients for novel forms or novel loading conditions. Physical modelling is also used later in the design process to deal with complex issues for which the available numerical models are not adequate or are inefficient, and it is subsequently used to provide a verification of the final design under a comprehensive set of load cases.All of these applications of physical models remain important in the move to very deep water, but the limitations of water depth, plan area and velocity profile in existing laboratory facilities reduce the capability of physical modelling. At the same time the wide range of novel hull forms, mooring configurations and materials, and riser types increases the requirement for physical data to calibrate the numerical models and increases the need for design validation. Physical modelling procedures, facilities and limitations are discussed and a design methodology is outlined.

Identifying Physico-Chemical Laws from the Robotically Collected Data

2019 ◽  
Author(s):  
Liwei Cao ◽  
Danilo Russo ◽  
Vassilios S. Vassiliadis ◽  
Alexei Lapkin
Keyword(s):  
Experimental Data ◽  
Numerical Models ◽  
Predictor Variable ◽  
Physical Models ◽  
Training Data ◽  
Mixed Integer ◽  
Physico Chemical ◽  
Data Points ◽  
Future Work ◽  
The Relationship

<p>A mixed-integer nonlinear programming (MINLP) formulation for symbolic regression was proposed to identify physical models from noisy experimental data. The formulation was tested using numerical models and was found to be more efficient than the previous literature example with respect to the number of predictor variables and training data points. The globally optimal search was extended to identify physical models and to cope with noise in the experimental data predictor variable. The methodology was coupled with the collection of experimental data in an automated fashion, and was proven to be successful in identifying the correct physical models describing the relationship between the shear stress and shear rate for both Newtonian and non-Newtonian fluids, and simple kinetic laws of reactions. Future work will focus on addressing the limitations of the formulation presented in this work, by extending it to be able to address larger complex physical models.</p><p><br></p>

scholarly journals Computational Fluid Dynamics Modeling of Rotating Annular VUV/UV Photoreactor for Water Treatment

Processes ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 79
Author(s):  
Minghan Luo ◽  
Wenjie Xu ◽  
Xiaorong Kang ◽  
Keqiang Ding ◽  
Taeseop Jeong
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Water Treatment ◽  
Cfd Modeling ◽  
Flow Mode ◽  
Oh Radicals ◽  
Dynamics Modeling ◽  
Rotational Movement ◽  
Contaminant Degradation ◽  
Wide Range

The ultraviolet photochemical degradation process is widely recognized as a low-cost, environmentally friendly, and sustainable technology for water treatment. This study integrated computational fluid dynamics (CFD) and a photoreactive kinetic model to investigate the effects of flow characteristics on the contaminant degradation performance of a rotating annular photoreactor with a vacuum-UV (VUV)/UV process performed in continuous flow mode. The results demonstrated that the introduced fluid remained in intensive rotational movement inside the reactor for a wide range of inflow rates, and the rotational movement was enhanced with increasing influent speed within the studied velocity range. The CFD modeling results were consistent with the experimental abatement of methylene blue (MB), although the model slightly overestimated MB degradation because it did not fully account for the consumption of OH radicals from byproducts generated in the MB decomposition processes. The OH radical generation and contaminant degradation efficiency of the VUV/UV process showed strong correlation with the mixing level in a photoreactor, which confirmed the promising potential of the developed rotating annular VUV reactor in water treatment.

scholarly journals An Alternative Statistical Model for Predicting Salinity Variations in Estuaries

2020 ◽  
Vol 12 (24) ◽  
pp. 10677
Author(s):  
Ronghui Ye ◽  
Jun Kong ◽  
Chengji Shen ◽  
Jinming Zhang ◽  
Weisheng Zhang
Keyword(s):  
Statistical Model ◽  
River Discharge ◽  
Numerical Models ◽  
Low Cost ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Large River ◽  
Physical Models ◽  
Long Term Effects ◽  
Salinity Variations

Accurate salinity prediction can support the decision-making of water resources management to mitigate the threat of insufficient freshwater supply in densely populated estuaries. Statistical methods are low-cost and less time-consuming compared with numerical models and physical models for predicting estuarine salinity variations. This study proposes an alternative statistical model that can more accurately predict the salinity series in estuaries. The model incorporates an autoregressive model to characterize the memory effect of salinity and includes the changes in salinity driven by river discharge and tides. Furthermore, the Gamma distribution function was introduced to correct the hysteresis effects of river discharge, tides and salinity. Based on fixed corrections of long-term effects, dynamic corrections of short-term effects were added to weaken the hysteresis effects. Real-world model application to the Pearl River Estuary obtained satisfactory agreement between predicted and measured salinity peaks, indicating the accuracy of salinity forecasting. Cross-validation and weekly salinity prediction under small, medium and large river discharges were also conducted to further test the reliability of the model. The statistical model provides a good reference for predicting salinity variations in estuaries.

Sign in / Sign up

Export Citation Format

Share Document