Modeling of Fluid Interaction Produced by Water Hammer

2011 ◽  
Vol 1 (1) ◽  
pp. 29-41 ◽  
Author(s):  
Kaveh Hariri Asli ◽  
Faig Bakhman Ogli Naghiyev ◽  
Soltan Ali Ogli Aliyev ◽  
Hoosein Hariri Asli
Keyword(s):  
Method Of Characteristics ◽  
Transient Flow ◽  
Practical Investigations ◽  
Computationally Efficient ◽  
Hydraulic Simulation ◽  
Computational Performance ◽  
Difference Form ◽  
Large Water ◽  
Water Transmission ◽  
Fluid Interaction

This paper compares the computational performance of two numerical methods for two models of Transient Flow. One model was defined by method of the Eulerian based expressed in a method of characteristics “MOC”, finite difference form. The other model was defined by method of Regression. Each method was encoded into an existing hydraulic simulation model. Results indicated that the accuracy of the methods was comparable but that the “MOC” was more computationally efficient for analysis of large water transmission line. Practical investigations in this article have shown mainly this tendency.

Modeling of Fluid Interaction Produced by Water Hammer

2013 ◽  
pp. 27-39
Author(s):  
Kaveh Hariri Asli ◽  
Faig Bakhman Ogli Naghiyev ◽  
Soltan Ali Ogli Aliyev ◽  
Hoosein Hariri Asli
Keyword(s):  
Transient Flow ◽  
Practical Investigations ◽  
The Other ◽  
Computationally Efficient ◽  
Hydraulic Simulation ◽  
Computational Performance ◽  
Difference Form ◽  
Large Water ◽  
Water Transmission ◽  
Fluid Interaction

This paper compares the computational performance of two numerical methods for two models of Transient Flow. One model was defined by method of the Eulerian based expressed in a method of characteristics “MOC”, finite difference form. The other model was defined by method of Regression. Each method was encoded into an existing hydraulic simulation model. Results indicated that the accuracy of the methods was comparable but that the “MOC” was more computationally efficient for analysis of large water transmission line. Practical investigations in this article have shown mainly this tendency.

Influence of velocity head on filling transients in a branched pipeline

2018 ◽  
Vol 35 (7) ◽  
pp. 2502-2513 ◽  
Author(s):  
Ling Wang ◽  
Fujun Wang ◽  
Bryan William Karney ◽  
Ahmad Malekpour ◽  
Zhengwei Wang
Keyword(s):  
Method Of Characteristics ◽  
Energy Equation ◽  
Transient Flow ◽  
Numerical Results ◽  
Velocity Head ◽  
Piezometric Head ◽  
Content Type ◽  
High Point ◽  
Hydraulic Transient ◽  
Column Separation

Purpose The velocity head is usually neglected in the energy equation for a pipeline junction when one-dimensional (1D) hydraulic transient flow is solved by method of characteristics. The purpose of this paper is to investigate the effect of velocity head on filling transients in a branched pipeline by an energy equation considering velocity head. Design/methodology/approach An interface tracking method is used to locate the air–water interface during pipeline filling. The pressured pipe flow is solved by a method of characteristics. A discrete gas cavity model is included to permit the occurrence of column separation. A universal energy equation is built by considering the velocity head. The numerical method is provisionally verified in a series pipeline and the numerical results and experimental data accord well with each other. Findings The numerical results show that some differences in filling velocity and piezometric head occur in the branched pipeline. These differences arise because the velocity head in the energy equation can become an important contributor to the hydraulic response of the system. It is also confirmed that a local high point in the profile is apt to experience column separation during rapid filling. Significantly, the magnitude of overpressure and cavity volume induced by filling transients at the local high point is predicted to increase with the velocity in the pipes. Originality/value The velocity head in the energy equation for a pipeline junction could play an important role in the prediction of filling velocity, piezometric head and column separation phenomenon, which should be given more attention in 1D hydraulic transient analysis.

scholarly journals Computationally-Efficient Distributed Algorithms of Navigation of Teams of Autonomous UAVs for 3D Coverage and Flocking

Drones ◽  
2021 ◽  
Vol 5 (4) ◽  
pp. 124
Author(s):  
Taha Elmokadem ◽  
Andrey V. Savkin
Keyword(s):  
Obstacle Avoidance ◽  
Precision Agriculture ◽  
Control Strategies ◽  
Autonomous Underwater Vehicles ◽  
Three Dimensional ◽  
Problem Formulation ◽  
Computationally Efficient ◽  
Control Approach ◽  
Computational Performance ◽  
Coverage Problems

This paper proposes novel distributed control methods to address coverage and flocking problems in three-dimensional (3D) environments using multiple unmanned aerial vehicles (UAVs). Two classes of coverage problems are considered in this work, namely barrier and sweep problems. Additionally, the approach is also applied to general 3D flocking problems for advanced swarm behavior. The proposed control strategies adopt a region-based control approach based on Voronoi partitions to ensure collision-free self-deployment and coordinated movement of all vehicles within a 3D region. It provides robustness for the multi-vehicle system against vehicles’ failure. It is also computationally-efficient to ensure scalability, and it handles obstacle avoidance on a higher level to avoid conflicts in control with the inter-vehicle collision avoidance objective. The problem formulation is rather general considering mobile robots navigating in 3D spaces, which makes the proposed approach applicable to different UAV types and autonomous underwater vehicles (AUVs). However, implementation details have also been shown considering quadrotor-type UAVs for an example application in precision agriculture. Validation of the proposed methods have been performed using several simulations considering different simulation platforms such as MATLAB and Gazebo. Software-in-the-loop simulations were carried out to asses the real-time computational performance of the methods showing the actual implementation with quadrotors using C++ and the Robot Operating System (ROS) framework. Good results were obtained validating the performance of the suggested methods for coverage and flocking scenarios in 3D using systems with different sizes up to 100 vehicles. Some scenarios considering obstacle avoidance and robustness against vehicles’ failure were also used.

Modeling Arbitrarily Shaped Liquid Pipelines Using a Segmented Transmission Line Model

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Travis Wiens
Keyword(s):  
Transmission Line ◽  
Method Of Characteristics ◽  
Previous Method ◽  
New Method ◽  
Transmission Line Model ◽  
Computationally Efficient ◽  
Time Step ◽  
Line Model ◽  
Order Of Magnitude ◽  
Variable Time Step

Abstract This paper presents a new method of simulating the dynamic flow and pressure of laminar liquid flow through pipes of arbitrarily changing cross section. This method uses a segmented model based on the previously presented tapered transmission line model (TLM). This new method is computationally efficient and has comparable accuracy to previous methods such as the method of characteristics (MOC), but allow for more flexibility in solution time-step (such as accommodating variable time-step solvers), which is required if the rest of the system model has stiff equations. For the sample geometry presented, the new model calculates the dynamic response an order of magnitude faster than the previous method of characteristics solution, with minimal loss of accuracy.

scholarly journals Numerical modeling transient flow in plastic pipes

2019 ◽  
Vol 286 ◽  
pp. 07001
Author(s):  
N. Achak ◽  
B. Bahrar ◽  
K. Gueraoui
Keyword(s):  
Numerical Modeling ◽  
Constitutive Equations ◽  
Method Of Characteristics ◽  
Transient Flow ◽  
Pipe Wall ◽  
Digital Processing ◽  
Numerical Code ◽  
Plastic Pipes ◽  
And Behavior ◽  
Good Agreement

We present a numerical code for calculating transient flow in plastic pipes, especially in the polyethylene pipe, to analysis effect of material viscoelasticity on water hammer phenomena. The set partial differential equations to be solved is obtained using conservation laws and behavior for the fluid and the pipe wall, associated with constitutive equations of the two media, and relationships compatibility of interfaces on velocities and stresses. A global digital processing is achieved using the method of characteristics. The results obtained are in good agreement with those found in the literature.

scholarly journals Three-Dimensional Hydromechanical Modeling during Shearing by Nonuniform Crust Movement

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Yuqing Zhao ◽  
You-Kuan Zhang ◽  
Xiuyu Liang
Keyword(s):  
Fluid Flow ◽  
Pore Pressure ◽  
Fault Zone ◽  
Numerical Models ◽  
Three Dimensional ◽  
Practical Investigations ◽  
Geological Formation ◽  
Distribution Of Stress ◽  
Coupling Processes ◽  
Fluid Interaction

Hydromechanical modeling of a geological formation under shearing by the nonuniform crust movement during 10000 years was carried out to investigate the solid stress and pore pressure coupling processes of the formation from the intact to the fractured or faulted. Two three-dimensional numerical models were built and velocities in opposite directions were applied on the boundaries to produce the shearing due to the nonuniform crust movement. The results show that the stress and pore pressure became more and more concentrated in and around the middle of the formation as time progresses. In Model I with no fault, stress and pore pressure are concentrated in the middle of the model during shearing; however, in Model II with a fault zone of weakened mechanical properties, they are more complex and concentrated along the sides of the fault zone and the magnitudes decreased. The distribution of stress determines pore pressure which in turn controls fluid flow. Fluid flow occurs in the middle in Model I but along the sides of the fault zone in Model II. The results of this study improve our understanding of the rock-fluid interaction processes affected by crustal movement and may guide practical investigations in geological formations.

Generating Simplified Trapping Probability Models From Simulation of Optical Tweezers System

2009 ◽  
Vol 9 (2) ◽  
Author(s):  
Ashis Gopal Banerjee ◽  
Arvind Balijepalli ◽  
Satyandra K. Gupta ◽  
Thomas W. LeBrun
Keyword(s):  
Optical Tweezers ◽  
Parameter Space ◽  
Computationally Efficient ◽  
Probability Models ◽  
Simplified Models ◽  
Simulation Data ◽  
Probability Estimates ◽  
Radial Basis ◽  
Difference Form ◽  
The Difference

This paper presents a radial basis function based approach to generate simplified models to estimate the trapping probability in optical trapping experiments using offline simulations. The difference form of Langevin’s equation is used to perform physically accurate simulations of a particle under the influence of a trapping potential and is used to estimate trapping probabilities at discrete points in the parameter space. Gaussian radial basis functions combined with kd-tree based partitioning of the parameter space are then used to generate simplified models of trapping probability. We show that the proposed approach is computationally efficient in estimating the trapping probability and that the estimated probability using the simplified models is sufficiently close to the probability estimates from offline simulation data.

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