Numerical Modeling of LES Based Turbulent Flow Induced Vibration

2003 ◽  
Author(s):  
Matthew T. Pittard ◽  
Jonathan D. Blotter
Keyword(s):  
Turbulent Flow ◽  
Flow Rate ◽  
Fluid Transport ◽  
Pipe Wall ◽  
Navier Stokes ◽  
Flow Induced Vibration ◽  
Flow Models ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Pipe Vibration

Flow-induced vibration caused by fully developed pipe flow has been recognized, but not fully investigated under turbulent conditions. This paper focuses on the development of a numerical, fluid-structure interaction (FSI) model that will help define the relationship between pipe wall vibration and the physical characteristics of turbulent flow. Commercial FSI software packages are based on Reynolds Averaged Navier-Stokes (RANS) fluid models which do not compute the instantaneous fluctuations in turbulent flow. This paper presents an FSI approach based on Large Eddy Simulation (LES) flow models that compute the instantaneous fluctuations in turbulent flow. The results based on the LES models indicate that these fluctuations contribute to the pipe vibration. It is shown that there is a near quadratic relationship between the standard deviation of the pressure field on the pipe wall and the flow rate. It is also shown that a strong relatonship between pipe vibration and flow rate exists. This research has a direct impact on the geothermal, nuclear, and other fluid transport industries.

Large Eddy Simulation of Single-Sided Ventilated Room With Different Location of Windows

2014 ◽  
Author(s):  
A. Idris ◽  
B. P. Huynh
Keyword(s):  
Large Eddy Simulation ◽  
Flow Pattern ◽  
Flow Rate ◽  
Natural Ventilation ◽  
Air Flow ◽  
Navier Stokes ◽  
Eddy Motion ◽  
Eddy Simulation ◽  
Continuity Equations ◽  
Large Eddy

The natural ventilation contributes the improvement of internal thermal comfort and internal air quality when applied properly. An investigation of single-sided double opening was performed to a 3-dimensional rectangular-box room using a commercial Computational Fluid Dynamics (CFD) software package of ESI group. Sixteen models with different location of double-openings were investigated. The large eddy simulation (LES) turbulence model was used to predict the air’s flow rate and air flow pattern. The governing equations for large eddy motion was obtained by filtering the Navier-Stokes and continuity equations. From the overall results, the lowest and the highest air flow rates were obtained to be 1.14 × 10−3 m3/s and 2.12 × 100 m3/s respectively. The location & arrangement of opening influences the air flow rate and air flow pattern.

Detection of memory loss of symmetry in the blockage of a turbulent flow within a duct

2017 ◽  
Vol 28 (06) ◽  
pp. 1750079 ◽  
Author(s):  
F. Rodrigues Santos ◽  
G. da Silva Costa ◽  
A. T. da Cunha Lima ◽  
M. P. de Almeida ◽  
I. C. da Cunha Lima
Keyword(s):  
Turbulent Flow ◽  
Numerical Solutions ◽  
Stokes Equations ◽  
Memory Loss ◽  
Point Of View ◽  
Navier Stokes ◽  
Turbulent Model ◽  
Navier Stokes Equations ◽  
Eddy Simulation ◽  
Large Eddy

This paper aims to detect memory loss of the symmetry of blockades in ducts and how far the information on the asymmetry of the obstacles travels in the turbulent flow from computational simulations with OpenFOAM. From a practical point of view, it seeks alternatives to detect the formation of obstructions in pipelines. The numerical solutions of the Navier–Stokes equations were obtained through the solver PisoFOAM of the OpenFOAM library, using the large Eddy simulation (LES) for the turbulent model. Obstructions were placed near the duct inlet and, keeping the blockade ratio fixed, five combinations for the obstacles sizes were adopted. The results show that the information about the symmetry is preserved for a larger distance near the ducts wall than in mid-channel. For an inlet velocity of 5[Formula: see text]m/s near the walls the memory is kept up to distance 40 times the duct width, while in mid-channel this distance is reduced almost by half. The maximum distance in which the symmetry breaking memory is preserved shows sensitivity to Reynolds number variations in regions near the duct walls, while in the mid channel that variations do not cause relevant effects to the velocity distribution.

Lattice Boltzmann Method Based on Large-Eddy Simulation (LES) Used to Investigate the Unsteady Turbulent Flow on Series of Cavities

2020 ◽  
Author(s):  
Insaf Mehrez ◽  
Ramla Gheith ◽  
Fethi Aloui
Keyword(s):  
Boltzmann Equation ◽  
Turbulent Flow ◽  
Turbulent Flows ◽  
Lattice Boltzmann ◽  
Turbulence Modeling ◽  
Stokes Equations ◽  
Numerical Study ◽  
Navier Stokes ◽  
Eddy Simulation ◽  
Large Eddy

Abstract A numerical study is proposed to analyze the turbulent flow structures. This paper aims to determine the effect of the series of the cavities. The configuration is similar to that represented by two walls with infinite width, one of which is mobile and the other is fixed. The series of cavity are placed on the fixed wall. The objectives are to study the aero acoustic capabilities of LBM and to build and to assess the efficiency of the Lattice Boltzmann Equation (LBE) as a new computational tool to perform the Large-Eddy Simulations (LES) for turbulent flows. In the first part, the background of LBM is presented and the construction of Navier-Stokes equations from Boltzmann equation is discussed. The LBM-LES model for solving transition is developed and turbulence modeling is implemented. In the second part, the dynamics of the flows in the vicinity of cavities with symmetric or asymmetric edges are considered, to then discuss the oscillation phenomenon. The effect of the geometric of the cavity and the Reynolds numbers were studied to investigate the fluid flow dynamics. We were focusing on the dynamics of asymmetric deep cavity flows, to put forward the topology of the cavity flow and to highlight the effects of dissymmetry and aspect ratio.

Towards Large-Eddy Simulation of Turbulent Flow in a Centrifugal Impeller

2011 ◽  
Author(s):  
Gorazd Medic ◽  
Jinzhang Feng ◽  
Liwei Chen ◽  
Om Sharma
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flow ◽  
Eddy Viscosity ◽  
Turbulence Models ◽  
Scale Model ◽  
Navier Stokes ◽  
Centrifugal Impeller ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Large Eddy

Large-eddy simulation (LES) using wall-adapting local eddy-viscosity (WALE) subgrid scale model has been applied towards elucidating the complex turbulent flow physics in a centrifugal impeller. Several canonical cases of increased complexity were analyzed to better understand the advantages and challenges of applying the LES framework to the aforementioned target problem. These include turbulent flow in a rotating channel, a straight and a curved duct. Results obtained with LES are compared in detail with two-equation eddy-viscosity Reynolds Averaged Navier-Stokes (RANS) turbulence models widely used in industry, as well as, for some of the canonical cases, with hybrid RANS/LES approaches such as the detached eddy simulation (DES) and scale-adaptive simulation (SAS). Finally, LES has been applied to turbulent flow in NASA CC3 centrifugal impeller with grids of increased resolution (up to 100 million computational cells per passage).

Steady-State and Unsteady Simulations of a High Velocity Jet Into a Venturi Shaped Pipe

2014 ◽  
Author(s):  
Bernhard Semlitsch ◽  
Estelle Laurendeau ◽  
Mihai Mihăescu
Keyword(s):  
Steady State ◽  
Flow Field ◽  
Large Eddy Simulation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Navier Stokes ◽  
Jet Pump ◽  
Eddy Simulation ◽  
Large Eddy

A jet pump consists mainly of a convergent-divergent Venturi shaped duct where a primary stream is applied with the role of entraining a secondary jet. Due to their simple and reliable concept, jet pumps are used in miscellaneous applications. Performance optimization of a jet pump has to be performed for various operation conditions. Thus, numerically robust and cheap models, able to predict accurately the performance parameters of such devices are necessary. Reynolds Averaged Navier-Stokes based formulations are computationally efficient to predict the performance of a jet pump. However, these simulations rely on turbulence closure coefficients, which need to be validated with experimental observations. Large Eddy Simulation solves the most energetic structures in the flow field and it can be used to capture the flow dynamics. On the experimental side, confined geometries challenge the investigation capabilities to capture the flow field accurately and in all the details. The flow field in the jet pump is investigated using Large Eddy Simulation approach and a steady state Reynolds Averaged Navier-Stokes formulation. The flow field solutions obtained with the two numerical tools are compared. A reasonable agreement for the velocity and pressure contours could be achieved. However, the turbulence kinetic energy distribution and the entrained mass flow rate are predicted to be distinct. The difference in entrained mass flow rate leads to differences in jet pump efficiency estimation.

NUMERICAL STUDY OF DETONATION PROPAGATION IN VISCOUS TURBULENT FLOW IN A DUCT

2020 ◽  
Author(s):  
V. A. SABELNIKOV ◽  
◽  
V. V. VLASENKO ◽  
S. BAKHNE ◽  
S. S. MOLEV ◽  
...  
Keyword(s):  
Complex Geometry ◽  
Numerical Study ◽  
Navier Stokes ◽  
Detonation Waves ◽  
Detonation Propagation ◽  
Eddy Simulation ◽  
Detonation Structure ◽  
Classical Studies ◽  
Large Eddy ◽  
Physical Effects

Gasdynamics of detonation waves was widely studied within last hundred years - analytically, experimentally, and numerically. The majority of classical studies of the XX century were concentrated on inviscid aspects of detonation structure and propagation. There was a widespread opinion that detonation is such a fast phenomenon that viscous e¨ects should have insigni¦cant in§uence on its propagation. When the era of calculations based on the Reynolds-averaged Navier- Stokes (RANS) and large eddy simulation approaches came into effect, researchers pounced on practical problems with complex geometry and with the interaction of many physical effects. There is only a limited number of works studying the in§uence of viscosity on detonation propagation in supersonic §ows in ducts (i. e., in the presence of boundary layers).

Constrained large-eddy simulation of turbulent flow over rough walls

2021 ◽  
Vol 6 (4) ◽  
Author(s):  
Wen Zhang ◽  
Minping Wan ◽  
Zhenhua Xia ◽  
Jianchun Wang ◽  
Xiyun Lu ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flow ◽  
Eddy Simulation ◽  
Rough Walls ◽  
Large Eddy

scholarly journals Comparative Study of Different Turbulence Models for Cavitational Flows around NACA0012 Hydrofoil

2021 ◽  
Vol 9 (7) ◽  
pp. 742
Author(s):  
Minsheng Zhao ◽  
Decheng Wan ◽  
Yangyang Gao
Keyword(s):  
Angle Of Attack ◽  
Large Angle ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Specific Information ◽  
Cloud Cavitation ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Shedding Frequency ◽  
Reynolds Average

The present work focuses on the comparison of the numerical simulation of sheet/cloud cavitation with the Reynolds Average Navier-Stokes and Large Eddy Simulation(RANS and LES) methods around NACA0012 hydrofoil in water flow. Three kinds of turbulence models—SST k-ω, modified SST k-ω, and Smagorinsky’s model—were used in this paper. The unstable sheet cavity and periodic shedding of the sheet/cloud cavitation were predicted, and the simulation results, namelycavitation shape, shedding frequency, and the lift and the drag coefficients of those three turbulence models, were analyzed and compared with each other. The numerical results above were basically in accordance with experimental ones. It was found that the modified SST k-ω and Smagorinsky turbulence models performed better in the aspects of cavitation shape, shedding frequency, and capturing the unsteady cavitation vortex cluster in the developing and shedding period of the cavitation at the cavitation number σ = 0.8. At a small angle of attack, the modified SST k-ω model was more accurate and practical than the other two models. However, at a large angle of attack, the Smagorinsky model of the LES method was able to give specific information in the cavitation flow field, which RANS method could not give. Further study showed that the vortex structure of the wing is the main cause of cavitation shedding.

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