Flow Computations of Rib-Roughened Cooling Channels With RANS and Scale Resolving Simulation Models

2017 ◽  
Author(s):  
İlhan Görgülü ◽  
Ender Hepkaya
Keyword(s):  
Numerical Simulations ◽  
Experimental Studies ◽  
Flow Simulation ◽  
Turbulence Models ◽  
Simulation Models ◽  
Reynolds Stress Model ◽  
Industrial Applications ◽  
Test Case ◽  
Detached Eddy Simulation ◽  
Eddy Simulation

In this research, experimental studies conducted by Casarsa [1] were used as test case to validate flow simulation methods. In the numerical simulations, four RANS turbulence models (k-ε, k-ω, V2-f and Reynolds Stress Model) and a URANS model which are widely used in industrial applications were employed for preliminary analyses. In addition, Scale-Adaptive Simulation (SAS), Detached Eddy Simulation (DES) and Large Eddy Simulation (LES) models are conducted to examine the capabilities of Scale Resolving Simulation (SRS) models. All numerical simulations were performed on two different grid resolutions. Relevance of the grid resolutions to the applied SRS methodologies have been assessed both with crude estimations obtained from the RANS simulations and examination of LES solutions. Findings were presented at various parallel and perpendicular planes with respect to the side walls and different over and inter-rib space locations in the form of mean and root mean square (rms) velocity profiles. In all comparisons, SRS results revealed an inarguable superiority over RANS models as expected. Among the SRS models, SAS model has been considered as the most promising industrial purpose model because of providing similar quality results by allowing higher time steps and coarser grid resolutions.

scholarly journals Prediction of flow and dispersion in cross–ventilated buildings

2019 ◽  
Vol 128 ◽  
pp. 05002
Author(s):  
Ali Cemal Benim ◽  
Michael Diederich ◽  
Ali Nahavandi
Keyword(s):  
Computational Analysis ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Turbulence Structure ◽  
Detached Eddy Simulation ◽  
Mean Velocity ◽  
Eddy Simulation ◽  
Large Eddy ◽  
The Mean ◽  
Grid Independence

The present paper presents a detailed computational analysis of flow and dispersion in a generic isolated single–zone buildings. First, a grid generation strategy is discussed, that is inspired by a previous computational analysis and a grid independence study. Different turbulence models are appliedincluding two-equation turbulence models, the differential Reynolds Stress Model, Detached Eddy Simulation and Zonal Large Eddy Simulation. The mean velocity and concentration fields are calculated and compared with the measurements. A satisfactory agreement with the experiments is not observed by any of the modelling approaches, indicating the highly demanding flow and turbulence structure of the problem.

scholarly journals Turbulence Modeling a Review for Different Used Methods

2021 ◽  
Vol 39 (1) ◽  
pp. 227-234
Author(s):  
Khelifa Hami
Keyword(s):  
Turbulence Modeling ◽  
Stokes Equations ◽  
Turbulence Models ◽  
Simulation Models ◽  
Navier Stokes ◽  
Future Research ◽  
Detached Eddy Simulation ◽  
Navier Stokes Equations ◽  
Eddy Simulation ◽  
Complicated Geometries

This contribution represents a critical view of the advantages and limits of the set of mathematical models of the physical phenomena of turbulence. Turbulence models can be grouped into two categories, depending on how turbulent quantities are calculated: direct numerical simulations (DNS) and RANS (Reynolds Averaged Navier-Stokes Equations) models. The disadvantage of these models is that they require enormous computing power, inaccessible, especially for large and complicated geometries. For this reason, hybrid models (combinations between DNS and RANS methods) have been developed, for example, the LES (“Large Eddy Simulation”) or DES (“Detached Eddy Simulation”) models. They represent a compromise - are less precise than DNS, but more precise than RANS models. The results presented in this contribution will allow and facilitate future research in the field the choice of the model approach necessary for the case studies whatever their difficulty factor.

scholarly journals Turbulence Models for Simulation of the Flow in a Rotor-Stator Cavity

2019 ◽  
Vol 213 ◽  
pp. 02104
Author(s):  
Lucie Zemanová ◽  
Pavel Rudolf
Keyword(s):  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Operating Conditions ◽  
Narrow Gap ◽  
Detached Eddy Simulation ◽  
Axial Thrust ◽  
Eddy Simulation ◽  
Adaptive Simulation ◽  
Large Eddy

Modelling of the flow in the cavities between rotor and stator in turbomachines (e.g. pumps or turbines) is a task of great interest. Correctly evaluated pressure and velocity fields enable calculation of the disk losses and therefore assessment of efficiency. It is also crucial for determination of axial thrust and thus design of the bearings. The study demonstrates abilities of various turbulence models to describe the flow in a narrow gap between rotating and stationary disks. Numerical simulations were performed in order to find out the ability of particular models to capture unstable structures appearing during specific operating conditions as well as to calculate the velocity profiles precisely. Large Eddy Simulation (LES), Scale Adaptive Simulation (SAS), Detached Eddy Simulation (DES), Reynolds stress model (RSM) and SST k – ω model were used. Obtained results were also compared with experimental measurement published by Viazzo et al. [1]

Selection of Suitable Turbulence Models for Numerical Modelling of Hydrocyclones

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
Mohsen Karimi ◽  
Guven Akdogan ◽  
Ali Dehghani ◽  
Steven Bradshaw
Keyword(s):  
Swirling Flow ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Boussinesq Hypothesis ◽  
Large Eddy ◽  
Comprehensive Survey ◽  
Computational Fluid Dynamics Cfd ◽  
Les Model

The capability of Computational Fluid Dynamics (CFD) alternates the interest of researcher from the empirical models into the numerical approaches for studying hydrocyclones. This paper presents a comprehensive survey on the influences of turbulence model options in the 3D simulation of the hydrocyclone flow pattern. The required grid resolution was selected through a grid independency study. Four categories of turbulence models involving models based on the Boussinesq hypothesis, the Reynolds Stress Model (RSM), the Large Eddy Simulation (LES) model, and the Detached Eddy Simulation (DES) model were investigated for prediction of velocity components within the hydrocyclone. The methodology was validated by experimental data. The results confirm that both RSM and LES models are efficient turbulent model choices for the simulation of swirling flow of hydrocyclones.

Large Eddy Simulation of the Heat Transfer Due to Swirling and Non-Swirling Jet Impingement

2008 ◽  
Author(s):  
Naseem Uddin ◽  
S. O. Neumann ◽  
B. Weigand
Keyword(s):  
Heat Transfer ◽  
Turbulence Models ◽  
Jet Impingement ◽  
Impinging Jet ◽  
Test Case ◽  
Complex Flow ◽  
Free Jet ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Target Wall

Turbulent impinging jet is a complex flow phenomenon involving free jet, impingement and subsequent wall jet development zones; this makes it a difficult test case for the evaluation of new turbulence models. The complexity of the jet impingement can be further amplified by the addition of the swirl. In this paper, results of Large Eddy Simulations (LES) of swirling and non-swirling impinging jet are presented. The Reynolds number of the jet based on bulk axial velocity is 23000 and target-to-wall distance (H/D) is two. The Swirl numbers (S) of the jet are 0,0.2, 0.47. In swirling jets, the heat transfer at the geometric stagnation zone deteriorates due to the formation of conical recirculation zone. It is found numerically that the addition of swirl does not give any improvement for the over all heat transfer at the target wall. The LES predictions are validated by available experimental data.

Combination of DES and DDES with a Correlation Based Transition Model

2013 ◽  
Vol 444-445 ◽  
pp. 374-379 ◽  
Author(s):  
Lei Qiao ◽  
Jun Qiang Bai ◽  
Jun Hua ◽  
Chen Wang
Keyword(s):  
Present Article ◽  
Test Case ◽  
Transition Model ◽  
Detached Eddy Simulation ◽  
Combined Model ◽  
Trailing Edge ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Stall Angle ◽  
Edge Separation

The present article describes the combination of the correlation based transition model of Menter et al. with the Detached Eddy Simulation (DES) and Delayed Detached Eddy Simulation (DDES) methodology. The interaction between transition model and DES or DDES method was investigated by T3A test case. The grid sensitivity of the combined methodology is discussed and the resolution is given. Then, the simulation of flow over foil of medium thick at stall angle was performed. The combined methodology produce results that have better agreement with experiment comparing to RANS transition model or fully turbulent DES/DDES alone. And the DDES based combined model shows a better agreement with experiment in the simulation of trailing edge separation comparing to DES based combined model.

PIV validation of different turbulence models used for numerical simulation of a centrifugal pump diffuser

2018 ◽  
Vol 35 (1) ◽  
pp. 2-17 ◽  
Author(s):  
Ling Zhou ◽  
Ling Bai ◽  
Wei Li ◽  
Weidong Shi ◽  
Chuan Wang
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Turbulence Models ◽  
Detached Eddy Simulation ◽  
Piv Measurements ◽  
Content Type ◽  
Rotating Speed ◽  
Eddy Simulation ◽  
Image Velocimetry ◽  
Velocity Flow

Purpose The purpose of this study is to validate the different turbulence models using in the numerical simulation of centrifugal pump diffuser. Computational fluid dynamics (CFD) has become the main method to study the pump inner flow patterns. It is important to understand the differences and features of the different turbulence models used in turbomachinery. Design/methodology/approach The velocity flow fields in a compact return diffuser under different flow conditions are studied and compared between CFD and particle image velocimetry (PIV) measurements. Three turbulence models are used to solve the steady flow field using high-quality fine structured grids, including shear stress transport (SST) k-w model, detached-eddy simulation (DES) model and SST k-w model with low-Re corrections. Findings SST k-w model with low-Re correction gives better results compared to DES and SST k-w model, and gives a good predication about the vortex core position under strong part-loading conditions. Originality/value A special test rig is designed to carry out the 2D PIV measurements under high rotating speed of 2850 r/min, and the PIV results are used to validate the CFD results.

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.

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.

Vortex-Induced Motion of a Square Cylinder at Moderate Reynolds Numbers

2016 ◽  
Author(s):  
Chih-Hua Wu ◽  
Shengwei Ma ◽  
Chang-Wei Kang ◽  
Teck-Bin Arthur Lim ◽  
Rajeev Kumar Jaiman ◽  
...  
Keyword(s):  
Vortex Shedding ◽  
Bluff Body ◽  
Computational Cost ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Spanwise Direction ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Cylinder Length ◽  
Induced Motion

Bluff body structures exposed to ocean current can undergo vortex-induced motion (VIM) for certain geometric and physical conditions. Recently, the study of VIM has been gaining attention for many engineering applications, in particular offshore structures such as buoys, FPSOs, semi-submersibles, Spars and TLPs. The present work is a part of a systematic effort to investigate the VIM response of multi-columns floating platform. In real sea condition, floating platforms are in high Reynolds numbers region and flow patterns around structures are turbulent in nature. For the purpose of investigating and simulating accurately the nonlinear dynamic processes of vortex shedding, transport and wake interactions with the bluff body, the fundamental study of VIM around a square column at moderate Reynolds numbers (1500 ≤ Re ≤ 14000) is firstly investigated. In the present work, the transient flow pattern around a free vibrating square cylinder at moderate Reynolds numbers is numerically investigated by an open source CFD toolbox, OpenFOAM. Good consistency and agreement are found between the present numerical findings and that of experiments. The cylinder, with a blockage area of 4.2%, is mounted on an elastic support for free vibration in the transverse direction. Hybrid RANS-LES turbulence models are considered here for accurate prediction of massively separated turbulent wake flow while maintaining the reasonable computational cost. Three hybrid turbulence models, the DDES (Delayed Detached Eddy Simulation, the k-ω SST-DES (Detached Eddy Simulation), and the k–ω SST-SAS (Scale Adaptive Simulation), are studied and their results are compared with the reported experimental measurements. It is shown that the result of simulation with the k–ω SST-SAS model is closer to the reported literature than the other two and therefore, subsequently adopted for all the simulations of our study in this paper. The scaling effect of cylinder length in the spanwise direction is also studied with the objective to reduce the computational cost. From the comparison with the recent experimental measurements, the discrepancy between the present simulations of reducing cylinder length and the experiment increases only when Re ≥ 4000. This might stem from the increase in wavelength of some vortex shedding modes and turbulence intensity variation in the spanwise direction near the cylinder as Re ≥ 4000. The detailed flow patterns, 3D vortex structures (based on Q-criterion) and vortex-shedding modes are presented in this work as well.

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