Nonlinear spectral dynamic analysis of guyed towers. Part II: Manitoba towers case study

2004 ◽  
Vol 31 (6) ◽  
pp. 1061-1076 ◽  
Author(s):  
A M Horr ◽  
A Yibulayin ◽  
P Disney
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Complex Geometry ◽  
Spectral Element ◽  
Wind Loading ◽  
Space Structures ◽  
Loading Test ◽  
Large Space ◽  
Post Buckling ◽  
Guyed Towers

Dynamic response of large complex space structures under wind loading is important in terms of performance and safety. Conventional method of wind loading calculation has been used successfully in codes to analyze large space structures. The method can be applied by approximating the air pressure, induced by wind, on the surfaces of structures. Although this replaces a wind loading test using complicated wind tunnel tests for any structural systems, the accuracy of the method, in the case of complex geometry guyed tower structures, is a matter of consideration. Hence, it is desirable to search for a procedure with more accuracy and reliability. In this respect, attention is paid to the advanced spectral element method and the computational fluid dynamics. Using the proposed formulation, a material and geometric nonlinear dynamic analyses have been performed to simulate post-buckling behaviours and also collapse modes for series of Manitoba Hydro's guyed towers under extreme wind loading conditions. Key words: computational fluid dynamics, wind loading, collapse mode, nonlinear analysis, post-buckling.

Computational Wind Tunnel Analyses for Large Domes Using CFD Theory

2003 ◽  
Vol 18 (2) ◽  
pp. 85-104
Author(s):  
A.M. Horr ◽  
M. Safi ◽  
S.A. Alavinasab
Keyword(s):  
Wind Tunnel ◽  
Complex Geometry ◽  
Complex Structure ◽  
Wind Tunnel Test ◽  
Wind Loading ◽  
Space Structures ◽  
Loading Test ◽  
Large Space ◽  
Large Space Structures ◽  
Computational Fluid Dynamics Cfd

Dynamic response of large complex dome structures under wind loading is important in terms of performance and safety. Conventional methods of wind loading calculation have been used successfully in codes to analyse large space structures. The method can be performed by approximating the air pressure, induced by wind, on the surfaces of structures. Although this replaces a wind loading test using a complicated wind tunnel test for any structural systems, the accuracy of the method, in the case of complex geometry structures, is a matter of consideration. Hence, it is desirable to search for a procedure with more accuracy and reliability. In this respect, attention is paid to advanced computational fluid dynamics (CFD), which benefits from the accurate mathematical differential equations. The use of the advanced CFD analysis can help engineers to design a complex structure, like a large dome, with a lower cost and lower weight. Using a computer program, the proposed formulation has been used to create a computational wind tunnel to derive the pressure loading on structures.

Nonlinear spectral dynamic analysis of guyed towers. Part I: Theory

2004 ◽  
Vol 31 (6) ◽  
pp. 1051-1060 ◽  
Author(s):  
A M Horr
Keyword(s):  
Dynamic Analysis ◽  
Nonlinear Dynamic ◽  
Spectral Element Method ◽  
Spectral Element ◽  
Space Structures ◽  
Large Space ◽  
Analysis And Design ◽  
Large Space Structures ◽  
Guyed Towers ◽  
Element Method

One of the important parameters in the analysis and design of large space structures is to account for the dynamic forces induced by wind and the subsequent progressive collapse. During the past two decades, problems of extreme loading conditions have been considered by some authors, and special attention has been devoted to the collapse modes. Nonlinear time history dynamic analysis, involving the post-buckling characteristics of the space structures, may be analyzed using the conventional finite element method. However, to guarantee stability and accuracy of the solution, the number of elements used to model the structure may be very large. In this respect, the nonlinear spectral element method (SEM) is developed for analyzing dynamic problems in large space structures. Through use of a computer program, the proposed method has been used to obtain the nonlinear dynamic response of guyed power transmission towers under severe wind loading condition. Key words: nonlinear dynamic analysis, space structures, guyed towers, spectral element method.

Computational Fluid Dynamics Modelling of a Load Sensing Proportional Valve

2019 ◽  
Author(s):  
Alessandro Corvaglia ◽  
Giorgio Altare ◽  
Roberto Finesso ◽  
Massimo Rundo
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Steady State ◽  
Complex Geometry ◽  
Ansys Fluent ◽  
Proportional Valve ◽  
Fluid Forces ◽  
Load Sensing ◽  
Cfd Models ◽  
Dynamics Modelling

Abstract In this paper, two 3D CFD models of a load sensing proportional valve are contrasted. The models were developed with two different software, Simerics PumpLinx® and ANSYS Fluent®. In both cases the mesh was dynamically modified based on the fluid forces acting on the local compensator. In the former, a specific template for valves was used, in the latter a user-defined function was implemented. The models were validated in terms of flow rate and pressure drop for different positions of the main spool by means of specific tests. Two configurations were tested: with the local compensator blocked and free to regulate. The study has brought to evidence the reliability of the CFD models in evaluating the steady-state characteristics of valves with complex geometry.

A Computational Fluid Dynamics (CFD) Study of Material Transport and Deposition in Aerosol Jet Printing (AJP) Process

2018 ◽  
Author(s):  
Roozbeh (Ross) Salary ◽  
Jack P. Lombardi ◽  
Darshana L. Weerawarne ◽  
Prahalada K. Rao ◽  
Mark D. Poliks
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Gas Flow ◽  
Complex Geometry ◽  
Sensor Data ◽  
Cfd Model ◽  
Material Transport ◽  
Jet Printing ◽  
Computational Fluid Dynamics Cfd ◽  
Aerosol Jet Printing

The objective of this work is to forward a 3D computational fluid dynamics (CFD) model to explain the aerodynamics behind aerosol transport and deposition in aerosol jet printing (AJP). The CFD model allows for: (i) mapping of velocity fields as well as particle trajectories; and (ii) investigation of post-deposition phenomena of sticking, rebounding, spreading, and splashing. The complex geometry of the deposition head was modeled in the ANSYS-Fluent environment, based on a patented design as well as accurate measurements, obtained from 3D X-ray CT imaging. The entire volume of the geometry was subsequently meshed, using a mixture of smooth and soft quadrilateral elements, with consideration of layers of inflation to obtain an accurate solution near the walls. A combined approach — based on the density-based and pressure-based Navier-Stokes formation — was adopted to obtain steady-state solutions and to bring the conservation imbalances below a specified linearization tolerance (10−6). Turbulence was modeled, using the realizable k-ε viscose model with scalable wall functions. A coupled two-phase flow model was set up to track a large number of injected particles. The boundary conditions were defined based on experimental sensor data. A single-factor factorial experiment was conducted to investigate the influence of sheath gas flow rate (ShGFR) on line morphology, and also validate the CFD model.

scholarly journals Computational Fluid Dynamics Analysis of Particle Deposition Induced by a Showerhead Electrode in a Capacitively Coupled Plasma Reactor

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1004
Author(s):  
Ho Jun Kim ◽  
Jung Hwan Yoon
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Particle Deposition ◽  
Complex Geometry ◽  
Plasma Reactor ◽  
Electrode Spacing ◽  
Plasma Discharges ◽  
Capacitively Coupled ◽  
Computational Fluid Dynamics Analysis ◽  
Capacitively Coupled Plasma

Defect formation in the deposition of thin films for semiconductors is not yet sufficiently understood. In a showerhead-type capacitively coupled plasma (CCP) deposition reactor, the showerhead acts as both the gas distributor and the electrode. We used computational fluid dynamics to investigate ways to enhance cleanliness by analyzing the particle deposition induced by the showerhead electrode in a CCP reactor. We analyzed particle transport phenomena using a three-dimensional complex geometry, whereas SiH4/He discharges were simulated in a two-dimensional simplified geometry. The process volume was located between the RF-powered showerhead and the grounded heater. We demonstrated that the efficient transportation of particles with a radius exceeding 1 μm onto the heater is facilitated by acceleration inside the showerhead holes. Because the available space in which to flow inside the showerhead is constricted, high gas velocities within the showerhead holes can accelerate particles and lead to inertia-enhanced particle deposition. The effect of the electrode spacing on the deposition of particles generated in plasma discharges was also investigated. Smaller electrode spacing promoted the deposition of particles fed from the showerhead on the heater, whereas larger electrode spacing facilitated the deposition of particles generated in plasma discharges on the heater.

scholarly journals Prediction of fire loading on the structures using computational fluid dynamics

2020 ◽  
Vol 313 ◽  
pp. 00033
Author(s):  
Romana Erdelyiová ◽  
Lucia Figuli ◽  
Matúš Ivančo
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Structure Design ◽  
Gas Temperature ◽  
Fire Load ◽  
Fire Dynamics ◽  
Large Space ◽  
Space Objects ◽  
Fire Loading ◽  
A Performance

The development of a fire in a large-space fire section differs significantly from the development in a small fire section. In large-space objects, to design structures under the fire load often proceeds through a performance-based approach. Advanced methods can be used in all parts of the design in predicting of the scatter of temperature field, in calculating of the heat transfer to the structure and in assessing of the mechanical behaviour of the structure or its part under the fire load. The prediction of the gas temperature in the fire compartment is crucial for the structure design. The paper is focused on selection of different fire scenarios in the large-space building. The aim is to provide background for structural design in a fire using a performance-based design. The problem is solved by using FDS (Fire Dynamics Simulator) software based on the CFD (Computational Fluid Dynamics) method.

Computational Fluid Dynamics Investigation of Supercritical Water Flow and Heat Transfer in a Rod Bundle With Grid Spacers

2016 ◽  
Vol 2 (3) ◽  
Author(s):  
Malwina Gradecka ◽  
Roman Thiele ◽  
Henryk Anglart
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Water Flow ◽  
Supercritical Water ◽  
Complex Geometry ◽  
Inlet Section ◽  
Fluid Temperature ◽  
Rod Bundle ◽  
Flow And Heat Transfer

This paper presents a steady-state computational fluid dynamics approach to supercritical water flow and heat transfer in a rod bundle with grid spacers. The current model was developed using the ANSYS Workbench 15.0 software (CFX solver) and was first applied to supercritical water flow and heat transfer in circular tubes. The predicted wall temperature was in good agreement with the measured data. Next, a similar approach was used to investigate three-dimensional (3D) vertical upward flow of water at supercritical pressure of about 25 MPa in a rod bundle with grid spacers. This work aimed at understanding thermo- and hydrodynamic behavior of fluid flow in a complex geometry at specified boundary conditions. The modeled geometry consisted of a 1.5-m heated section in the rod bundle, a 0.2-m nonheated inlet section, and five grid spacers. The computational mesh was prepared using two cell types. The sections of the rods with spacers were meshed using tetrahedral cells due to the complex geometry of the spacer, whereas sections without spacers were meshed with hexahedral cells resulting in a total of 28 million cells. Three different sets of experimental conditions were investigated in this study: a nonheated case and two heated cases. The nonheated case, A1, is calculated to extract the pressure drop across the rod bundle. For cases B1 and B2, a heat flux is applied on the surface of the rods causing a rise in fluid temperature along the bundle. While the temperature of the fluid increases along with the flow, heat deterioration effects can be present near the heated surface. Outputs from both B cases are temperatures at preselected locations on the rods surfaces.

Computational Fluid Dynamics (CFD) Simulation of Liquid-Liquid Mixing in Mixer Settler

2012 ◽  
Vol 57 (1) ◽  
pp. 173-178 ◽  
Author(s):  
M. Shabani ◽  
A. Mazahery
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Process Simulation ◽  
Chemical Process ◽  
Cfd Simulation ◽  
Complex Geometry ◽  
Physical Parameters ◽  
Cfd Model ◽  
Liquid Mixing ◽  
Computational Fluid Dynamics Cfd

Computational Fluid Dynamics (CFD) Simulation of Liquid-Liquid Mixing in Mixer Settler Mixer-settlers are widely used inmetallurgical, mineral and chemical process. One of the greatest challenges in the area of hydrometallurgy process simulation is agitation made by impeller inside mixer-settler which yet presents one of the most common operations. Computational fluid dynamics (CFD) model has been developed to predict the effect of different physical parameters including temperature and density on the mixing characteristics of the system. It is noted that non-isotropic nature of flow in a mixer-settler, the complex geometry of rotating impellers and the large disparity in geometric scales present are some of the factors which contribute to the simulation difficulty. The experimental data for different velocity outlet was also used in order to validate the model.

Parametric Numerical Simulation of Mean Wind Loading on Stadium Cantilevered Roofs

2011 ◽  
Vol 243-249 ◽  
pp. 989-994
Author(s):  
Ying Sun ◽  
Bo Xiang ◽  
Bin Lin ◽  
Yue Wu
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Computational Fluid Dynamics ◽  
Empirical Equation ◽  
Ventilation Rate ◽  
Wind Loading ◽  
Incoming Flow ◽  
Wind Force ◽  
Roof Structure ◽  
The Mean

Studies on the characteristics of the mean wind load acting on the cantilevered roofs are carried out systematically by CFD (Computational Fluid Dynamics) numerical simulation. The influences of some factors, including the incoming flow condition, inclination angle of roofs and the ventilation rate above grandstand, on mean wind loading are investigated. It is found that the terrain type and grandstand type are not significantly influence the mean wind loads on the roof structure; The wind force acting on roof is increased with roof pitch; Sub-roof venting is found to reduce uplifts by no more than 12%; Introducing a similar shaped grandstand upstream is found to significantly decrease the wind loading. Based on these results, an empirical equation for the calculation of mean wind loading is derived for the reference of designers.

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