Experimental and numerical analyses of gas–solid-multiphase jet in cross-flow

2012 ◽  
Vol 227 (1) ◽  
pp. 61-79 ◽  
Author(s):  
Yao Fu ◽  
Tong Wang ◽  
Chuangang Gu
Keyword(s):  
Flow Field ◽  
Transient Flow ◽  
Cross Flow ◽  
Jet Flow ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Calculation Methods ◽  
Mean Flow ◽  
Eddy Simulation ◽  
Reynolds Averaged Navier Stokes

In this article, jet influence on a gas–solid-multiphase channel flow was experimentally and numerically studied. The jet flow was found to have a diameter-selective controlling effect on the particles’ distribution. Jet flow formed a gas barrier in the channel for particles. While tiny particles could travel around and large particles could travel through, only particles on the 10 -µm scale were obviously affected. Three different calculation methods, Reynolds averaged Navier–Stokes, unsteady Reynolds averaged Navier–Stokes, and detached eddy simulation, were used to simulate this multiphase flow. By comparing the calculation results to the experimental results, it is found that all the three calculation methods could capture the basic phenomenon in the mean flow field. Nevertheless, there exist great differences in the transient flow field and particle distribution.

scholarly journals Comparative Study on CFD Turbulence Models for the Flow Field in Air Cooled Radiator

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1687
Author(s):  
Chao Yu ◽  
Xiangyao Xue ◽  
Kui Shi ◽  
Mingzhen Shao ◽  
Yang Liu
Keyword(s):  
Flow Field ◽  
Transient Flow ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Compartment Model ◽  
Navier Stokes ◽  
Engine Compartment ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Relevant Calculation

This paper compares the performances of three Computational Fluid Dynamics (CFD) turbulence models, Reynolds Average Navier-Stokes (RANS), Detached Eddy Simulation (DES), and Large Eddy Simulation (LES), for simulating the flow field of a wheel loader engine compartment. The distributions of pressure fields, velocity fields, and vortex structures in a hybrid-grided engine compartment model are analyzed. The result reveals that the LES and DES can capture the detachment and breakage of the trailing edge more abundantly and meticulously than RANS. Additionally, by comparing the relevant calculation time, the feasibility of the DES model is proved to simulate the three-dimensional unsteady flow of engine compartment efficiently and accurately. This paper aims to provide a guiding idea for simulating the transient flow field in the engine compartment, which could serve as a theoretical basis for optimizing and improving the layout of the components of the engine compartment.

Numerical investigation of vortex-induced vibration of an elastically mounted circular cylinder with One-degree of freedom at high Reynolds number using different turbulent models

2018 ◽  
Vol 233 (2) ◽  
pp. 443-453 ◽  
Author(s):  
Niaz Bahadur Khan ◽  
Zainah Ibrahim
Keyword(s):  
Reynolds Number ◽  
Flow Direction ◽  
Cross Flow ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Flow Around Cylinder ◽  
Reynolds Averaged Navier Stokes ◽  
Turbulent Models

This study presents numerical investigation for flow around cylinder at Reynolds number = 104 using different turbulent models. Numerical simulations have been conducted for fixed cylinder case at Reynolds number = 104 and for cylinder free to oscillate in cross-flow direction, at Reynolds number O (104), mass–damping ratio = 0.011 and range of frequency ratio wt = 0.4–1.4 using two-dimensional Reynolds-averaged Navier–Stokes equations. In the literature, the study has been conducted using detached eddy simulation, large eddy simulation and direct numerical simulation which are comparatively expensive in terms of computational cost. This study utilizes the Reynolds-averaged Navier–Stokes shear stress transport k-ω and realizable k-ε models to investigate the flow around fixed cylinder and flow around cylinder constrained to oscillate in cross-flow direction only. Hydrodynamic coefficients, vortex mode shape and maximum amplitude ( Ay/ D) extracted from this study are compared with detached eddy simulation, large eddy simulation and direct numerical simulation results. Results obtained using two-dimensional Reynolds-averaged Navier–Stokes shear stress transport k-ω model are encouraging, while realizable k-ε model is unable to capture the entire response branches. In addition, broad range of “lock-in” region is observed due to delay in capturing the transition from upper to lower branch during two-dimensional realizable k-ε analyses.

A Comparative Study of DES and URANS in a Two-Pass Internal Cooling Duct With Normal Ribs

2005 ◽  
Author(s):  
Aroon K. Viswanathan ◽  
Danesh K. Tafti
Keyword(s):  
Heat Transfer ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Internal Cooling ◽  
Detached Eddy Simulation ◽  
Mean Flow ◽  
Streamline Curvature ◽  
Eddy Simulation ◽  
Flow And Heat Transfer ◽  
Developing Flow

The capabilities of the Detached Eddy Simulation (DES) and the Unsteady Reynolds Averaged Navier-Stokes (URANS) versions of the 1988 κ-ω model in predicting the turbulent flow field and the heat transfer in a two-pass internal cooling duct with normal ribs is presented. The flow is dominated by the separation and reattachment of shear layers; unsteady vorticity induced secondary flows and strong streamline curvature. The techniques are evaluated in predicting the developing flow at the entrance to the duct and downstream of the 180° bend, fully-developed regime in the first pass, and in the 180° bend. Results of mean flow quantities, secondary flows, friction and heat transfer are compared to experiments and Large-Eddy Simulations (LES). DES predicts a slower flow development than LES, while URANS predicts it much earlier than LES computations and experiments. However it is observed that as fully developed conditions are established, the capability of the base model in predicting the flow and heat transfer is enhanced by switching to the DES formulation. DES accurately predicts the flow and heat transfer both in the fully-developed region as well as the 180° bend of the duct. URANS fails to predict the secondary flows in the fully-developed region of the duct and is clearly inferior to DES in the 180° bend.

Detached-Eddy Simulations and Reynolds-Averaged Navier-Stokes Simulations of Delta Wing Vortical Flowfields

2002 ◽  
Vol 124 (4) ◽  
pp. 924-932 ◽  
Author(s):  
Scott Morton ◽  
James Forsythe ◽  
Anthony Mitchell ◽  
David Hajek
Keyword(s):  
Vortex Breakdown ◽  
Delta Wing ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Fighter Aircraft ◽  
Eddy Simulation ◽  
Reynolds Averaged Navier Stokes ◽  
High Reynolds

An understanding of vortical structures and vortex breakdown is essential for the development of highly maneuverable vehicles and high angle of attack flight. This is primarily due to the physical limits these phenomena impose on aircraft and missiles at extreme flight conditions. Demands for more maneuverable air vehicles have pushed the limits of current CFD methods in the high Reynolds number regime. Simulation methods must be able to accurately describe the unsteady, vortical flowfields associated with fighter aircraft at Reynolds numbers more representative of full-scale vehicles. It is the goal of this paper to demonstrate the ability of detached-eddy Simulation (DES), a hybrid Reynolds-averaged Navier-Stokes (RANS)/large-eddy Simulation (LES) method, to accurately predict vortex breakdown at Reynolds numbers above 1×106. Detailed experiments performed at Onera are used to compare simulations utilizing both RANS and DES turbulence models.

On the Investigation of Flow around the Square Cylinder Based on Different LES Models

2012 ◽  
Vol 594-597 ◽  
pp. 2676-2679
Author(s):  
Zhe Liu
Keyword(s):  
Flow Characteristics ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Square Cylinder ◽  
Rans Model ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Reynolds Averaged Navier Stokes ◽  
Les Model

Although the conventional Reynolds-averaged Navier–Stokes (RANS) model has been widely applied in the industrial and engineering field, it is worthwhile to study whether these models are suitable to investigate the flow filed varying with the time. With the development of turbulence models, the unsteady Reynolds-averaged Navier–Stokes (URANS) model, detached eddy simulation (DES) and large eddy simulation (LES) compensate the disadvantage of RANS model. This paper mainly presents the theory of standard LES model, LES dynamic model and wall-adapting local eddy-viscosity (WALE) LES model. And the square cylinder is selected as the research target to study the flow characteristics around it at Reynolds number 13,000. The influence of different LES models on the flow field around the square cylinder is compared.

Partially Averaged Navier–Stokes (PANS) Method for Turbulence Simulations: Flow Past a Circular Cylinder

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Sunil Lakshmipathy ◽  
Sharath S. Girimaji
Keyword(s):  
Circular Cylinder ◽  
Navier Stokes ◽  
Length Scale ◽  
Detached Eddy Simulation ◽  
Mean Flow ◽  
Closure Model ◽  
Variable Resolution ◽  
Eddy Simulation ◽  
Flow Past ◽  
High Reynolds

The objective of this study is to evaluate the capability of the partially averaged Navier–Stokes (PANS) method in a moderately high Reynolds number (ReD 1.4×105) turbulent flow past a circular cylinder. PANS is a bridging closure model purported for use at any level of resolution ranging from Reynolds-averaged Navier–Stokes to direct numerical simulations. The closure model is sensitive to the length-scale cut-off via the ratios of unresolved-to-total kinetic energy (fk) and unresolved-to-total dissipation (fε). Several simulations are performed to study the effect of the cut-off length-scale on computed closure model results. The results from various resolutions are compared against experimental data, large eddy simulation, and detached eddy simulation solutions. The quantities examined include coefficient of drag (Cd), Strouhal number (St), and coefficient of pressure distribution (Cp) along with the mean flow statistics and flow structures. Based on the computed results for flow past circular cylinder presented in this paper and analytical attributes of the closure model, it is reasonable to conclude that the PANS bridging method is a theoretically sound and computationally viable variable resolution approach for practical flow computations.

Detached-Eddy Simulation of Flow Around the NREL Phase-VI Blade

2002 ◽  
Author(s):  
J. Johansen ◽  
N. N. So̸rensen ◽  
J. A. Michelsen ◽  
S. Schreck
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Simulation Model ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Reynolds Averaged Navier Stokes ◽  
Nrel Phase Vi

The Detached-Eddy Simulation model implemented in the computational fluid dynamics code, EllipSys3D, is applied on the flow around the NREL Phase-VI wind turbine blade. Results are presented for flow around a parked blade at fixed angle of attack and a blade pitching along the blade axis. Computed blade characteristics are compared with experimental data from the NREL/NASA Ames Phase-VI unsteady experiment. The Detached-Eddy Simulation model is a method for predicting turbulence in computational fluid dynamics computations, which combines a Reynolds Averaged Navier-Stokes method in the boundary layer with a Large Eddy Simulation in the free shear flow. The present study focuses on static and dynamic stall regions highly relevant for stall regulated wind turbines. Computations do predict force coefficients and pressure distributions fairly good and results using Detached-Eddy Simulation show considerably more three-dimensional flow structures compared to conventional two-equation Reynolds Averaged Navier-Stokes turbulence models, but no particular improvements are seen on the global blade characteristics.

scholarly journals Numerical Simulation and Characteristic Analysis of Ship's Air Flow Field

2018 ◽  
Vol 36 (6) ◽  
pp. 1037-1044
Author(s):  
Jiahao Guo ◽  
Xiaoping Zhu ◽  
Zhou Zhou ◽  
Xiaoping Xu
Keyword(s):  
Flow Field ◽  
Velocity Fluctuation ◽  
Air Flow ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Reasonable Accuracy ◽  
Characteristic Analysis ◽  
Eddy Simulation ◽  
Flight Deck ◽  
The Ideal

The air flow field of ship was simulated by using computational fluid dynamics technology to analyze its prime characteristics with reasonable accuracy. The different results of Reynolds-Averaged Navier-Stokes (RANS) method and Detached Eddy Simulation (DES) were compared, and the calculation traits of these methods were discussed. The results show that the air flow field of ship is unsteady. The accuracy of RANS simulation is insufficient for capturing this unsteady phenomenon. However, DES can catch this with better accuracy and expresses a comparatively great conformity with experimental data. Then, the aircraft carrier's flow field was calculated by DES. The characteristics of vortexes and velocity fluctuation on the ideal landing track were discussed in different wind directions. Those simulations indicate that there are complicated vortexes produced by blunt edges of the island and deck in the flow field. Those vortexes interact and mainly exist in the rear of flight deck and its adjacent air wake. Moreover, they cause a conspicuous and periodical velocity fluctuation on the ideal landing track as time goes on.

CFD Study of Propeller Cavitation With Hull-Propeller Interaction

2019 ◽  
Author(s):  
Chang Wei Kang ◽  
Xiuqing Xing
Keyword(s):  
Free Surface ◽  
Flow Field ◽  
High Performance ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Simulation Accuracy ◽  
Eddy Simulation ◽  
Marine Industry ◽  
Propeller Blades ◽  
Cfd Method

Abstract Propeller cavitation is the root cause for noise, hull vibration, as well as erosion on the propeller blades and appendages. Although it is a common practice for marine industry to predict the propeller cavitation by model tests, numerical simulation of propeller performance and the hull-propeller interaction has become feasible with the advancement of high performance computing. In this study, numerical studies of the flow field details around the ship hull with a rotating propeller are performed using Computational Fluid Dynamics (CFD) method by solving the unsteady Reynolds Averaged Navier-Stokes (RANS) equations. The numerical model is developed with commercial software package STAR-CCM+ for the cavitation prediction by considering the hull/propeller interactions and the free surface. Rotating propeller is modeled with an overset mesh, while κ-ω turbulence model is chosen instead of large eddy simulation (LES) or detached eddy simulation (DES) for higher computational efficiency while maintaining satisfied simulation accuracy. Cavitation bubble growth and collapse are estimated using Schnerr-Sauer cavitation model based on Rayleigh-Plesset equation. Simulation results suggest that the model developed in this study is capable to capture the flow field details under the effect of hull-propeller interactions and the free surface. This includes the cavitation emerging position, extinction position, as well as the cavitation patterns on the blade surface at various angular positions. The cavitation induced pressure oscillations on the hull at 1st to 3rd harmonics of Blade Passing Frequency (BPF) are also analyzed. The pressure fluctuation result can provide pressure load information for hull vibration evaluations in future.

scholarly journals Компьютерное моделирование течения в микрофакельных горелочных устройствах с асимметричной подачей топлива

2018 ◽  
Vol 28 (8) ◽  
pp. 117-121
Author(s):  
N. M. Fialko ◽  
V. G. Prokopov ◽  
S. O. Alioshko ◽  
M. Z. Abdulin ◽  
K. V. Rokitko ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Reynolds Averaged Navier Stokes

Выявлены основные закономерности изотермического течения топлива и окислителя в микрофакельном горелочном устройстве с односторонней подачей топлива. Получены данные компьютерного моделирования с использованием подхода DES (Detached Eddy Simulation), представляющего собой комбинацию моделей RANS (Reynolds Averaged Navier-Stokes) и LES (Large Eddy Simulation) в разных областях пространства. Установлены эффекты влияния длины закрылка, расположенного на торцевой поверхности стабилизаторов пламени, на различные характеристики течения. Показано, что наличие закрылков приводит к существенному изменению вихревой структуры в следе за стабилизаторами. Оценено влияние длины закрылков на такие параметры течения, как протяженность зоны обратных токов в закормовой области стабилизаторов пламени, уровень среднеквадратичных пульсаций скорости в данных зонах и пр. Установлено, что с увеличением длины закрылков существенно возрастает протяженность зоны обратных токов за стабилизатором. Выявлено также, что чем короче закрылки, тем больше превышает их длину протяженность зоны обратных токов. Выполнен анализ пространственного распределения пульсаций скорости в рассматриваемом горелочном устройстве при наличии и отсутствии закрылков на торцевых поверхностях стабилизаторов пламени. Показано, что наиболее высокий уровень данных пульсаций наблюдается вблизи границы зоны обратных токов, удаленной от торца стабилизатора. Установлено, что уровень среднеквадратичных пульсаций скорости является наиболее высоким в условиях отсутствия закрылка и снижается при увеличении его длины.

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