Freely Vibrating Two Side-by-Side Square Columns With Combined Translational Motions

2016 ◽  
Author(s):  
Meng-Zhao Guan ◽  
Rajeev K. Jaiman ◽  
Chang-Wei Kang ◽  
Teck-Bin Arthur Lim
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Low Reynolds Number ◽  
Wake Flow ◽  
Stationary Condition ◽  
Arbitrary Lagrangian Eulerian ◽  
Mesh Motion ◽  
Moderate Reynolds Number ◽  
Flow Induced Vibrations ◽  
Low Reynolds

This paper presents a set of numerical simulations of flow-induced vibrations (FIV) and coupled wake flow behind two identical square columns in a side-by-side configuration. To observe the four regimes as a function of different gap ratios, the computational results of the configuration at low Reynolds number Re=ρfUDμf in stationary condition are firstly compared with existing experimental data of moderate Reynolds number. We next investigate the configuration of elastically mounted square columns, which are free to oscillate in both streamwise and transverse directions. The simulations are performed by the Petrov-Galerkin finite-element method and Arbitrary Lagrangian-Eulerian technique to account for the fluid mesh motion. The four regimes of stationary side-by-side configuration follow the same trend of the experimental data conducted at moderate Reynolds number, while the ranges of each regime differ due to the turbulent wake properties. For the freely vibrating condition, all the simulations are computed at low Reynolds number (Re = 200), mass ratio equal to 10m*=Mmf and reduced velocity in the range of Ur ∈ [1,50] where Ur=UfND and in free-damping condition ζ = C2KM = 0. The four regimes in vibrating condition are investigated as a function of gap ratios g* = g/D, which is the ratio of spacing between the inner column surfaces to the diameter of the column. The effects of reduced velocity on the force variations, the vibration amplitudes and the vorticity contours are analyzed systematically to understand the underlying FIV physics of side-by-side columns in the four regimes. Finally, we present a FIV study of the full semi-submersible model at moderate Reynolds number Re = 20,000 which can be considered as the application of side-by-side configuration.

A Numerical Investigation of Transonic Axial Compressor Rotor Flow Using a Low-Reynolds-Number k–ε Turbulence Model

1999 ◽  
Vol 121 (1) ◽  
pp. 44-58 ◽  
Author(s):  
T. Arima ◽  
T. Sonoda ◽  
M. Shirotori ◽  
A. Tamura ◽  
K. Kikuchi
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Turbulence Model ◽  
Low Reynolds Number ◽  
Axial Compressor ◽  
Numerical Results ◽  
Speed Condition ◽  
Transonic Axial Compressor ◽  
Low Reynolds ◽  
Design Speed

We have developed a computer simulation code for three-dimensional viscous flow in turbomachinery based on the time-averaged compressible Navier–Stokes equations and a low-Reynolds-number k–ε turbulence model. It is described in detail in this paper. The code is used to compute the flow fields for two types of rotor (a transonic fan NASA Rotor 67 and a transonic axial compressor NASA rotor 37), and numerical results are compared to experimental data based on aerodynamic probe and laser anemometer measurements. In the case of Rotor 67, calculated and experimental results are compared under the design speed to validate the code. The calculated results show good agreement with the experimental data, such as the rotor performance map and the spanwise distribution of total pressure, total temperature, and flow angle downstream of the rotor. In the case of Rotor 37, detailed comparisons between the numerical results and the experimental data are made under the design speed condition to assess the overall quality of the numerical solution. Furthermore, comparisons under the part-speed condition are used to investigate a flow field without passage shock. The results are well predicted qualitatively. However, considerable quantitative discrepancies remain in predicting the flow near the tip. In order to assess the predictive capabilities of the developed code, computed flow structures are presented with the experimental data for each rotor and the cause of the discrepancies is discussed.

Vortex Flow Behind a Heaving Elastic Flat Plate

2008 ◽  
Author(s):  
Masaki Fuchiwaki ◽  
Kazuhiro Tanaka
Keyword(s):  
Reynolds Number ◽  
Flat Plate ◽  
Vortex Flow ◽  
Low Reynolds Number ◽  
Vertical Direction ◽  
Vortex Street ◽  
Wake Flow ◽  
Piv Measurement ◽  
Low Reynolds ◽  
Accelerating Flow

An unsteady flow in a low Reynolds number region attracts attention in recent years. Various experiments/numerical analyses have been conducted in wake flow fields of objects with unsteady motions in low Reynolds number regions have been studied and reported recently. The authors clarified vortical structures in a wake of a rigid airfoil (NACA0010) with pitching, heaving and an unsteady motion with these motions combined quantitatively. The purpose of this study is to evaluate quantitatively the vortex flow formed in the wake of a flat airfoil whose edge deforms elastically by a PIV measurement by giving a heaving motion to the flat plate in a low Reynolds number region. A clear thrust producing vortex street equivalent to the airfoil shape can be formed by giving elasticity to the latter part of a rigid flat airfoil. vortices forming the thrust producing vortex street is extremely large and their vorticity is equivalent to that of NACA0010. In the mainstream of a vortex street forming a propulsion power generating vortex street, the vortex interval in the vertical direction is comparatively large and an interference of the vortices rolling up from the pressure and suction sides is small therefore the accelerating flow induced by these vortices becomes as large as the mainstream. The dynamic thrust acting on the elastic flat plate is greater than that of NACA0010. Because vortices with high vorticity roll up and these vortices are aligned with a comparatively large vortex interval in the vertical direction therefore a large accelerating flow is induced in the wake.

Free Jet in Confined Combustion Chamber: Numerical Model for Industrial Application in Low NOx Burners

2005 ◽  
Author(s):  
Emanuela Colombo ◽  
Fabio Inzoli ◽  
Enrico Malfa
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Reynolds Number ◽  
Combustion Chamber ◽  
Fluid Dynamic ◽  
Low Reynolds Number ◽  
Turbulence Models ◽  
Dynamic Features ◽  
Low Reynolds ◽  
High Reynolds

The present work is focused on the prediction of the fluid dynamics behaviour for natural gas burners characterized by low NOx emissions. The fluid dynamics in the combustion chamber is investigated in order to look for the condition under which it is possible to obtain a diluted combustion. The experimental data used as reference come from two set of tests related to different isothermal flow behaviour: high Reynolds number (Re = 68000) and lower Reynolds number (Re = 5427). Many turbulence models are examined in order to validate high and low Reynolds case. The k-ω models implemented by Wilcox in 1998 seems to properly predict the fluid dynamics behaviour of the jet for high Reynolds numbers, while, for low Reynolds jets, a modification needs to be introduced. The numerical analysis for low Reynolds number, based on an unstructured 2D axial symmetrical grid, shows that no two-equation turbulence models fit the experimental data for low Reynolds jet. Based on the evidence that at low Reynolds number the hypothesis of homogeneous isotropic small turbulence eddy is not valid a modification of k-ω turbulence model’s closure constant has been proposed. This leads to a better agreement with the experimental data. The results demonstrate that great attention needs to be taken and invested in the identification of the turbulence models used in CFD and in the proper tunneling (of the closure coefficient for the turbulence model) that need to be computed case by case accordingly with the specific turbulence level and fluid dynamic features of the jet itself.

Unsteady Flow Separation and High Performance of Airfoil with Local Flexible Structure at Low Reynolds Number

2014 ◽  
Vol 16 (3) ◽  
pp. 699-717 ◽  
Author(s):  
Peng-Fei Lei ◽  
Jia-Zhong Zhang ◽  
Wei Kang ◽  
Sheng Ren ◽  
Le Wang
Keyword(s):  
Reynolds Number ◽  
Unsteady Flow ◽  
Flow Separation ◽  
High Performance ◽  
Energy Transport ◽  
Low Reynolds Number ◽  
Flexible Structure ◽  
Arbitrary Lagrangian Eulerian ◽  
Aeroelastic System ◽  
Low Reynolds

AbstractThe unsteady flow separation of airfoil with a local flexible structure (LFS) is studied numerically in Lagrangian frames in detail, in order to investigate the nature of its high aerodynamic performance. For such aeroelastic system, the characteristic-based split (CBS) scheme combined with arbitrary Lagrangian-Eulerian (ALE) framework is developed firstly for the numerical analysis of unsteady flow, and Galerkin method is used to approach the flexible structure. The local flexible skin of airfoil, which can lead to self-induced oscillations, is considered as unsteady perturbation to the flow. Then, the ensuing high aerodynamic performances and complex unsteady flow separation at low Reynolds number are studied by Lagrangian coherent structures (LCSs). The results show that the LFS has a significant influence on the unsteady flow separation, which is the key point for the lift enhancement. Specifically, the oscillations of the LFS can induce the generations of moving separation and vortex, which can enhance the kinetic energy transport from main flow to the boundary layer. The results could give a deep understand of the dynamics in unsteady flow separation and flow control for the flow over airfoil.

scholarly journals Numerical Predictions of Uniform CO2 Corrosion in Complex Fluid Domains Using Low Reynolds Number Models

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1001
Author(s):  
Haijun Hu ◽  
Hao Xu ◽  
Changmeng Huang ◽  
Xing Chen ◽  
Xiufeng Li ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mass Transfer ◽  
Reynolds Number ◽  
Low Reynolds Number ◽  
Co2 Corrosion ◽  
Aqueous Corrosion ◽  
Corrosion Rates ◽  
Complex Fluid ◽  
Low Reynolds ◽  
Near Wall

To get the knowledge of local corrosion, thinning is useful for developing targeted inspection plans for pipe components in the oil/gas industry. Aiming at this object, this work presents a computer fluid dynamics (CFD) method to predict CO2 aqueous corrosion in complex fluid domains. The processes involved in CO2 aqueous corrosion, including flow dynamics, mass transfer, chemical reactions, and electrochemical reactions, are modeled and simulated by a commercial CFD software of Fluent V15.0 (Version, manufacturer, city, country). Mass transfer in the straight pipe flow and jet impinging flow are simulated using three low-Reynolds-number turbulent models (Abe–Kondoh–Nagano k − ε model, Change–Hsieh–Chenk k − ε model, and k − ε shear stress transport model). The flow domains are meshed by grids with the first near-wall node at the position at y+ = 0.1. Comparisons between simulations and experimental data show the Abe–Kondoh–Nagano model provides the best predictions of near-wall flow and mass transfer. Thus, it is used to predict CO2 aqueous corrosion. Corrosion rates of dissolved CO2 in straight pipes and a jet impinging are predicted. The predicted corrosion rates are compared with experimental data and results derived from commercial software, Multicorp V5.2.105. The results show that predicted corrosion rates are reasonable. The locations of the highest corrosion rate for a jet impinging system are revealed.

scholarly journals A Numerical Investigation of Transonic Axial Compressor Rotor Flow Using a Low Reynolds Number k-ε Turbulence Model

1997 ◽  
Author(s):  
Toshiyuki Arima ◽  
Toyotaka Sonoda ◽  
Masatoshi Shirotori ◽  
Atsuhiro Tamura ◽  
Kazuo Kikuchi
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Turbulence Model ◽  
Low Reynolds Number ◽  
Axial Compressor ◽  
Numerical Results ◽  
Speed Condition ◽  
Transonic Axial Compressor ◽  
Low Reynolds ◽  
Design Speed

We have developed a computer simulation code for three-dimensional viscous flow in turbomachinery based on the time-averaged compressible Navier-Stokes equations and a low Reynolds number k-ε turbulence model. It is described in detail in this paper. The code is used to compute the flow fields for two types of rotor (a transonic fan NASA Rotor 67 and a transonic axial compressor NASA rotor 37), and numerical results are compared to experimental data based on aerodynamic probe and laser anemometer measurements. In the case of Rotor 67, calculated and experimental results are compared under the design speed to validate the code. The calculated results show good agreement with the experimental data, such as the rotor performance map and the spanwise distribution of total pressure, total temperature, and flow angle downstream of the rotor. In the case of Rotor 37, detailed comparisons between the numerical results and the experimental data are made under the design speed condition to assess the overall quality of the numerical solution. Furthermore, comparisons under the part speed condition are used to investigate a flow field without passage shock. The results are well predicted qualitatively. However, considerable quantitative discrepancies remain in predicting the flow near the tip. In order to assess the predictive capabilities of the developed code, computed flow structures are presented with the experimental data for each rotor and the cause of the discrepancies is discussed.

Direct numerical simulation of flow-induced vibrations of a wavy cable at a low Reynolds number

2021 ◽  
Vol 117 ◽  
pp. 102926
Author(s):  
Hongbo Zhu ◽  
Huan Ping ◽  
Yan Bao ◽  
Dai Zhou ◽  
Shuai Huang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Direct Numerical Simulation ◽  
Low Reynolds Number ◽  
Flow Induced Vibrations ◽  
Low Reynolds

3943 Wake-flow Measurements of Rectangular Wing at Low Reynolds Number

2006 ◽  
Vol 2006.2 (0) ◽  
pp. 377-378
Author(s):  
Hisaya SUGIYAMA ◽  
Akira MATSUMOTO ◽  
Naoki SEKIYA
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Wake Flow ◽  
Flow Measurements ◽  
Low Reynolds
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