Water Hammer (With FSI): Exact Solution — Parallelization and Application

2014 ◽  
Author(s):  
Kelvin Loh ◽  
Arris S. Tijsseling
Keyword(s):  
Exact Solution ◽  
Water Hammer ◽  
Structural Behaviour ◽  
Internal Fluid ◽  
Optimal Damping ◽  
Fluid Transients ◽  
Simple Recursion ◽  
Water Hammer Effect ◽  
Fully Coupled

The 1D fully coupled Fluid-Structure Interaction (FSI) model can adequately describe the water hammer effect on the fluid, and the structural behaviour of the pipe. This paper attempts to increase the capability of using an exact solution of the 1D FSI problem applied to a straight pipe with a valve. The work builds upon a simple recursion algorithm to obtain exact solutions. This paper describes the attempts to parallelize the time-consuming algorithm and presents an optimization case study. The algorithm has been parallelized using a Master-Slave MPI model for scalability. The applicability of this all has been explored by an optimization case study, which seeks the optimal damping coefficient of a dashpot connected to the valve to reduce the structural stresses in the pipe wall and the pressure in the fluid. Thus, an external damper is used to mitigate internal fluid transients.

scholarly journals Digital surveying and 3D modelling structural shape pipelines for instability monitoring in historical buildings: a strategy of versatile mesh models for ruined and endangered heritage

ACTA IMEKO ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 84
Author(s):  
Raffaella De Marco ◽  
Sandro Parrinello
Keyword(s):  
Laser Scanner ◽  
Structural Behaviour ◽  
Structural Shape ◽  
Built Heritage ◽  
Levels Of Detail ◽  
Aerial Vehicle ◽  
The Church ◽  
Mesh Models

Cultural heritage and the attendant variety of built heritage demands a scientific approach from European committees: one related to the difficulties in its protection and management. This is primarily due to the lack of emergency protocols related to the structural knowledge and documentation pertaining to architecture and its ruins, specifically in terms of the goals of protection and intervention for endangered heritage affected by mechanical instabilities. Here, we focus on a rapid and reliable structural documentation pipeline for application to historical built heritage, and we introduce a case study of the Church of the Annunciation in Pokcha, Russia, while we also review the incorporation of integrated 3D survey products into reality-based models. This practice increases the possibility of systematising data through methodological phases and controlling the quality of numerical components into 3D polygonal meshes, with millimetric levels of detail and triangulation through the integration of terrestrial laser scanner and unmanned aerial vehicle survey data. These models are aimed at emphasising morphological qualities related to structural behaviour, thus highlighting areas of deformation and instability of the architectural system for analysis via computational platforms in view of obtaining information related to tensional behaviour and emergency risks.

Rational Polynomial Transfer Function Approximations for Fluid Transients in Lines

2003 ◽  
Author(s):  
Patompong Wongputorn ◽  
David A. Hullender ◽  
Robert L. Woods
Keyword(s):  
Exact Solution ◽  
Transmission Lines ◽  
Transfer Functions ◽  
Viscous Friction ◽  
Total System ◽  
Nonlinear Frequency ◽  
Maximum Frequency ◽  
Rational Polynomial ◽  
Curve Fit ◽  
Fluid Transients

This paper introduces a simple approach utilizing MATLAB® computational tools for generating rational polynomial transfer functions for fluid transients in both liquid and gas fluid transmission lines. These transfer functions are obtained by curve fitting in the frequency domain the exact solution to the distributed parameter laminar flow “Dissipative Model” for fluid transients that includes nonlinear frequency dependent viscous friction terms as well as heat transfer effects in gas lines. These transfer functions are formulated so they are applicable to arbitrary line terminations and so they can be inserted directly into SIMULINK® models for time domain simulation and analysis of a total system of which the fluid lines are only internal components. The inputs to the algorithm are the internal radius and length of the line; the kinematic viscosity, density, Prandtl number, and speed of sound of the fluid; and the maximum frequency to which an accurate curve fit of the exact solution is desired. This maximum frequency normally is equal to or greater than the bandwidth of the other components in the total system to be analyzed or the maximum frequency associated with the input. The simplicity of use and accuracy in the results of the exact solution representations are demonstrated for examples of a blocked fluid line and of a line terminating into a tank. The computational algorithms are available for download from the Author’s web site. This is the first of two papers pertaining to transfer functions for fluid transients. The second paper pertains to formulating simulation diagrams for total systems containing fluid lines represented by rational polynomial transfer functions.

Analytical structural behaviour of elastic flapping wings under the actuator effect

2018 ◽  
Vol 122 (1254) ◽  
pp. 1176-1198
Author(s):  
H. Zare ◽  
Seid H. Pourtakdoust ◽  
A. Bighashdel
Keyword(s):  
Conceptual Understanding ◽  
Body Motion ◽  
Flapping Wings ◽  
Inertial Forces ◽  
Structural Behaviour ◽  
Initial Value ◽  
Sinusoidal Motion ◽  
Structural Responses ◽  
First Time

ABSTRACTThe effect of inertial forces on the Structural Dynamics (SD) behaviour of Elastic Flapping Wings (EFWs) is investigated. In this regard, an analytical modal-based SD solution of EFW undergoing a prescribed rigid body motion is initially derived. The formulated initial-value problem is solved analytically to study the EFW structural responses, and sensitivity with respect to EFWs’ key parameters. As a case study, a rectangular wing undergoing a prescribed sinusoidal motion is simulated. The analytical solution is derived for the first time and helps towards a conceptual understanding of the overall EFW's SD behaviour and its analysis required in their designs. Specifically, the EFW transient and steady response in on-off servo condition is also attended.

Hydraulic descaling improvement, findings of jet structure on water hammer effect

2007 ◽  
Vol 104 (2) ◽  
pp. 84-90 ◽  
Author(s):  
M. Raudensky ◽  
A. Horak ◽  
J. Horsky ◽  
M. Pohanka ◽  
P. Kotrbacek
Keyword(s):  
Water Hammer ◽  
Jet Structure ◽  
Water Hammer Effect

FHS Semi: A Semisubmersible Design for Dry Tree Applications

2009 ◽  
Author(s):  
Alaa M. Mansour
Keyword(s):  
Gulf Of Mexico ◽  
Water Depth ◽  
Time Domain ◽  
Frequency Range ◽  
Integration Technique ◽  
Natural Period ◽  
Ballast Tank ◽  
New Feature ◽  
Fully Coupled

In this paper the performance of a new conceptual semisubmersible design that provides motion response similar to a Spar is investigated. The new invention introduces a new feature which is the Free-Hanging Solid Ballast Tank, hence the name FHS Semi. The use of the free-hanging Solid Ballast Tank (SBT) significantly increases the heave natural period while controlling the heave response in the wave frequency range and, therefore, enables the use of the FHS Semi in dry tree applications. The new design’s quayside integration technique and its interface with the top tensioned risers are presented in this paper. Case study for the new design to support a 32,000 ST payload including 15 Top Tensioned Risers (TTRs) in an ultra-deepwater of 8,000 ft water depth is considered. Frequency domain and fully coupled time-domain hydrodynamic analyses have been performed and numerical results are presented to illustrate the new semisubmersible design response in extreme Gulf of Mexico hurricane events.

Fluid Transients in a Pipeline With One Open End

2008 ◽  
Author(s):  
Robert A. Leishear
Keyword(s):  
Water Hammer ◽  
Atmospheric Conditions ◽  
Air Entrapment ◽  
Complex Interactions ◽  
Fluid Transients ◽  
Pipe Line ◽  
Multi Phase Flow ◽  
Time Required ◽  
Multi Phase ◽  
Transparent Tube

Water hammer during multi-phase flow is rather complex, but in some cases an upper limit to the pressure surge magnitude during water hammer can be estimated. In the case considered here, a two mile long pipeline with a single high point was permitted to partially drain. Due to gravitational effects, air bubbles up through the pipe line to its highest point, but the time required for air to reach the top of the pipe is rather long. Consequently, some transients caused by valve operations are affected by air entrapment and some are not. The intent of this research was to investigate the complex interactions between air, water vapor, and liquid during water hammer in a long pipe with one end of the pipe open to atmospheric conditions. To understand the system dynamics, experimental data was obtained from a long pipeline with an open end and also from a short, transparent tube. Transient calculations were performed for valve closures and pump operations as applicable. The limitations of available calculation techniques were considered in detail.

New Designs in Fuel Dispensing System to Reduce Water Hammer

2013 ◽  
Author(s):  
Y. J. Liu ◽  
Z. Y. Wang ◽  
Z. Y. Huang ◽  
J. Lumkes
Keyword(s):  
Working Conditions ◽  
Rate Control ◽  
Water Hammer ◽  
Service Station ◽  
Start Up ◽  
Flow Rate Control ◽  
The Impact ◽  
Water Hammer Effect ◽  
Rapid Pressure ◽  
Nozzle Structure

Dispensers are used for refueling vehicles at the service station. During the refueling process, the velocity of fluid changes rapidly in several working conditions, which results in a rapid pressure increasing or a water hammer effect occurring. Water hammer, often causes leakage or failure of dispensers, occurs due to pump start-up and shut-down, valves opening or closing during the refueling process. This paper experimentally characterized and theoretically calculated the impact of water hammer on the dispensers at the service station. New designs of nozzle structure and new flow-rate control modes are made to reduce the water hammer in the fuel dispensing system. Eventually, all the water hammers are reduced significantly during the refueling process under the new design modes.

Viscous Dispersion in Water Hammer

1960 ◽  
Vol 82 (4) ◽  
pp. 759-763 ◽  
Author(s):  
M. L. Walker ◽  
E. T. Kirkpatrick ◽  
W. T. Rouleau
Keyword(s):  
Exact Solution ◽  
Upper Bound ◽  
Pressure Wave ◽  
Practical Interest ◽  
Water Hammer ◽  
Inviscid Fluid ◽  
Uniform Velocity ◽  
Step Discontinuity

When a column of fluid moving with uniform velocity is instantaneously stopped at the downstream end a pressure wave is propagated upstream. In an inviscid fluid the wave is a step discontinuity, and the pressure so calculated serves as an easily obtained upper bound for all practical “water-hammer” problems, the exact solution of which may be either difficult or impossible to obtain. This paper describes an analysis of viscous dispersion in relation to the upper bound. The conclusion is reached that in problems of practical interest the bound is not significantly changed by the dispersive effects of viscosity.

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