scholarly journals Low-Cost Eddy-Resolving Simulation in the Near-Field of an Annular Swirling Jet for Spray Drying Applications

2021 ◽  
Vol 5 (4) ◽  
pp. 80
Author(s):  
Jairo Andrés Gutiérrez Suárez ◽  
Alexánder Gómez Mejía ◽  
Carlos Humberto Galeano Urueña
Keyword(s):  
Spray Drying ◽  
Laser Doppler Anemometry ◽  
Low Cost ◽  
Near Field ◽  
Computational Cost ◽  
Individual Performance ◽  
Industrial Applications ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Swirling Jet

Spray drying is one of many industrial applications that use annular swirling jets. For this particular application, the flow characteristics in the near-field of the jet are fundamental to obtaining high-quality dried products. In this article, an annular swirling jet configuration is numerically studied using three low-cost eddy-resolving turbulence methods: detached-eddy simulation (DES), delayed-DES (DDES) and scale-adaptive simulation (SAS). To focus in industrial applicability, very coarse grids are used. The individual performance of these models is assessed through a comparison with laser-Doppler anemometry (LDA) measurements and large-eddy simulation (LES) data from available studies. Results show that all the three turbulence models are suitable for performing industrial cost-effective simulations, capable of reproducing LES results of mean velocities and first-order turbulence statistics at a fraction of the computational cost. Differences in the results of the evaluated models were minor; however, the simulation with DDES still provided a better reproduction of experimental results, especially in the very-near field of the jet, as it enforced RANS behavior near the inlet walls and a better transition from modeled to resolved scales.

scholarly journals Near-Field Simulations of Film Cooling with a Modified DES Model

Inventions ◽  
2020 ◽  
Vol 5 (1) ◽  
pp. 13
Author(s):  
Feiyan Yu ◽  
Savas Yavuzkurt
Keyword(s):  
Film Cooling ◽  
Eddy Viscosity ◽  
Near Field ◽  
Computational Cost ◽  
Vortex Pair ◽  
Anisotropy Ratio ◽  
Detached Eddy Simulation ◽  
Film Cooling Effectiveness ◽  
Eddy Simulation ◽  
Des Model

Modeling the heat transfer characteristics of highly turbulent flow in gas turbine film cooling is important for providing better insights and engineering solutions to the film cooling problem. This study proposes a modified detached eddy simulation (DES) model for better film cooling simulations. First, spatially varying anisotropic eddy viscosity is found from the results of the large eddy simulation (LES) of film cooling. Then the correlation for eddy viscosity anisotropy ratio has been established based on the LES results and is proposed as the modification approach for the DES model. The modified DES model has been tested for the near-field film cooling simulations under different blowing ratios. Detailed comparisons of the centerline and 2D film cooling effectiveness indicate that the modified DES model enhances the spanwise spreading of the temperature field. The DES model leads to deviations of 62.4%, 39.8%, and 33.5% from the experimental centerline effectiveness under blowing ratios of 0.5, 1.0, and 1.5, respectively, while the modified DES reduces the deviations to 51.5%, 26.7%, and 28.9%. The modified DES model provides a promising approach for film cooling numerical simulations. It embraces the advantage of LES in resolving detailed vortical structure dynamics with a moderate computational cost. It also significantly improves the original DES model on the spanwise counter rotating vortex pair (CRVP) spreading, mixing, and effectiveness prediction.

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.

Unsteady RANS and detached eddy simulation of the multiphase flow in a co-current spray drying

2015 ◽  
Vol 23 (9) ◽  
pp. 1421-1428 ◽  
Author(s):  
Jolius Gimbun ◽  
Noor Intan Shafinas Muhammad ◽  
Woon Phui Law
Keyword(s):  
Multiphase Flow ◽  
Spray Drying ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Unsteady Rans

Simulation of near-field dispersion of pollutants using detached-eddy simulation

2014 ◽  
Vol 100 ◽  
pp. 308-320 ◽  
Author(s):  
M. Lateb ◽  
C. Masson ◽  
T. Stathopoulos ◽  
C. Bédard
Keyword(s):  
Near Field ◽  
Detached Eddy Simulation ◽  
Eddy Simulation

Sensitivity Analysis and Multiobjective Optimization for LES Numerical Parameters

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
J.-C. Jouhaud ◽  
P. Sagaut ◽  
B. Enaux ◽  
J. Laurenceau
Keyword(s):  
Large Eddy Simulation ◽  
Surrogate Model ◽  
Low Cost ◽  
Linear Interpolation ◽  
Industrial Applications ◽  
Small Subset ◽  
Eddy Simulation ◽  
Subgrid Model ◽  
Large Eddy ◽  
Optimal Linear

Accuracy and reliability of large-eddy simulation data in a really complex industrial geometry are invesigated. An original methodology based on a response surface for LES data is introduced. This surrogate model for the full LES problem is built using the Kriging technique, which enables a low-cost optimal linear interpolation of a restricted set of large-eddy simulation (LES) solutions. Therefore, it can be used in most realistic industrial applications. Using this surrogate model, it is shown that (i) optimal sets of simulation parameters (subgrid model constant and artificial viscosity parameter in the present case) can be found; (ii) optimal values, as expected, depend on the cost functional to be minimized. Here, a realistic approach, which takes into account experimental data sparseness, is introduced. It is observed that minimization of the error evaluated using a too small subset of reference data may yield a global deterioration of the results.

Detached Eddy Simulation of the Turbulent Flow in a Stirred Tank

2011 ◽  
Vol 236-238 ◽  
pp. 1487-1491 ◽  
Author(s):  
Feng Ling Yang ◽  
Shen Jie Zhou ◽  
Gui Chao Wang
Keyword(s):  
Kinetic Energy ◽  
Turbulent Flow ◽  
Computational Cost ◽  
Stirred Tank ◽  
Detached Eddy Simulation ◽  
Mean Velocity ◽  
Eddy Simulation ◽  
Energy Profiles ◽  
Les Model ◽  
Des Model

In the present work, detached eddy simulation (DES) of the turbulent flow in an unbaffled stirred tank agitated by a six-pitched-blade turbine was carried out. The sliding mesh (SM) approach was applied to simulate the rotation of the impeller. For comparison, the computations based on the large eddy simulation (LES) model and RANS equations closed with Reynolds stress model (RSM) were also performed. The instantaneous velocity fluctuations, mean velocity and turbulent kinetic energy profiles were analyzed and compared with the laser doppler velocimetry (LDV) results from literature. Results show that DES model can capture the unsteady turbulent flow characteristics accurately. The mean velocity and turbulent kinetic energy profiles by the DES model are in good agreements with the LES results and the LDV data. Besides, the computational cost of DES is only about 80% of LES. By contrast, the results obtained by RSM are not so good. It can be concluded that the DES model can produce as similarly good predictions as LES with less computational cost, and can work as an alternative of the LES model in predicting the hydrodynamics in the stirred tanks.

Comparison of RANS and Detached Eddy Simulation Results to Wind-Tunnel Data for the Surface Pressures Upon a Class 43 High-Speed Train

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Justin A. Morden ◽  
Hassan Hemida ◽  
Chris. J. Baker
Keyword(s):  
Wind Tunnel ◽  
Surface Pressure ◽  
High Speed ◽  
Model Comparison ◽  
Computational Cost ◽  
Full Scale ◽  
Cost Comparison ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Wind Tunnel Data

Currently, there are three different methodologies for evaluating the aerodynamics of trains; full-scale measurements, physical modeling using wind-tunnel, and moving train rigs and numerical modeling using computational fluid dynamics (CFD). Moreover, different approaches and turbulence modeling are normally used within the CFD framework. The work in this paper investigates the consistency of two of these methodologies; the wind-tunnel and the CFD by comparing the measured surface pressure with the computed CFD values. The CFD is based on Reynolds-Averaged Navier–Stokes (RANS) turbulence models (five models were used; the Spalart–Allmaras (S–A), k-ε, k-ε re-normalization group (RNG), realizable k-ε, and shear stress transport (SST) k-ω) and two detached eddy simulation (DES) approaches; the standard DES and delayed detached eddy simulation (DDES). This work was carried out as part of a larger project to determine whether the current methods of CFD, model scale and full-scale testing provide consistent results and are able to achieve agreement with each other when used in the measurement of train aerodynamic phenomena. Similar to the wind-tunnel, the CFD approaches were applied to external aerodynamic flow around a 1/25th scale class 43 high-speed tunnel (HST) model. Comparison between the CFD results and wind-tunnel data were conducted using coefficients for surface pressure, measured at the wind-tunnel by pressure taps fitted over the surface of the train in loops. Four different meshes where tested with both the RANS SST k-ω and DDES approaches to form a mesh sensitivity study. The four meshes featured 18, 24, 34, and 52 × 106 cells. A mesh of 34 × 106 cells was found to provide the best balance between accuracy and computational cost. Comparison of the results showed that the DES based approaches; in particular, the DDES approach was best able to replicate the wind-tunnel results within the margin of uncertainty.

scholarly journals Effect of Local Grid Refinement on Performance of Scale-Resolving Models for Simulation of Complex External Flows

Aerospace ◽  
2019 ◽  
Vol 6 (8) ◽  
pp. 86 ◽  
Author(s):  
Amne ElCheikh ◽  
Michel ElKhoury
Keyword(s):  
Computational Cost ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Pollutant Dispersion ◽  
Uniform Grid ◽  
Grid Refinement ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Uniform Grids ◽  
Large Eddy

Numerical simulations are crucial for fast and accurate estimations of the flow characteristics in many engineering applications such as atmospheric boundary layers around buildings, external aerodynamics around vehicles, and pollutant dispersion. In the simulation of flow over urban-like obstacles, it is crucial to accurately resolve the flow characteristics with reasonable computational cost. Therefore, Large Eddy Simulations on non-uniform grids are usually employed. However, an undesirable accumulation of energy at grid-refinement interfaces was observed in previous studies using non-uniform grids. This phenomenon induced oscillations in the spanwise velocity component, mainly on fine-to-coarse grid interfaces. In this study, the two challenging test cases of flow over urban-like cubes and flow over a 3-D circular cylinder were simulated using three different scale-resolving turbulence models. Simulations were performed on uniform coarse and fine grids on one hand, and a non-uniform grid on the other, to assess the effect of mesh density and mesh interfaces on the models’ performance. Overall, the proposed One-Equation Scale-Adaptive Simulation (One-Equation SAS) showed the least deviation from the experimental results in both tested cases and on all grid sizes and types when compared to the Shear Stress Transport-Improved Delayed Detached Eddy Simulation (IDDES) and the Algebraic Wall-Modeled Large Eddy Simulation (WMLES).

scholarly journals Turbulence Modeling Effects on the CFD Predictions of Flow over a Detailed Full-Scale Sedan Vehicle

Fluids ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 148 ◽  
Author(s):  
Chunhui Zhang ◽  
Charles Patrick Bounds ◽  
Lee Foster ◽  
Mesbah Uddin
Keyword(s):  
Turbulence Modeling ◽  
Computational Cost ◽  
Turbulence Models ◽  
Relative Magnitude ◽  
Full Scale ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Rans Turbulence Models ◽  
Rans Models

In today’s road vehicle design processes, Computational Fluid Dynamics (CFD) has emerged as one of the major investigative tools for aerodynamics analyses. The age-old CFD methodology based on the Reynolds Averaged Navier–Stokes (RANS) approach is still considered as the most popular turbulence modeling approach in automotive industries due to its acceptable accuracy and affordable computational cost for predicting flows involving complex geometries. This popular use of RANS still persists in spite of the well-known fact that, for automotive flows, RANS turbulence models often fail to characterize the associated flow-field properly. It is even true that more often, the RANS approach fails to predict correct integral aerodynamic quantities like lift, drag, or moment coefficients, and as such, they are used to assess the relative magnitude and direction of a trend. Moreover, even for such purposes, notable disagreements generally exist between results predicted by different RANS models. Thanks to fast advances in computer technology, increasing popularity has been seen in the use of the hybrid Detached Eddy Simulation (DES), which blends the RANS approach with Large Eddy Simulation (LES). The DES methodology demonstrated a high potential of being more accurate and informative than the RANS approaches. Whilst evaluations of RANS and DES models on various applications are abundant in the literature, such evaluations on full-car models are relatively fewer. In this study, four RANS models that are widely used in engineering applications, i.e., the realizable k - ε two-layer, Abe–Kondoh–Nagano (AKN) k - ε low-Reynolds, SST k - ω , and V2F are evaluated on a full-scale passenger vehicle with two different front-end configurations. In addition, both cases are run with two DES models to assess the differences between the flow predictions obtained using RANS and DES.

Numerical Implementation of Detached-Eddy Simulation on a Passenger Vehicle and Some Experimental Correlation

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
L. Sterken ◽  
S. Sebben ◽  
L. Löfdahl
Keyword(s):  
Flow Characteristics ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Wake Flow ◽  
Computational Time ◽  
Detached Eddy Simulation ◽  
Passenger Vehicle ◽  
Ansys Fluent ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

This study presents an implementation of delayed detached-eddy simulation (DDES) on a full-scale passenger vehicle for three configurations with the use of commercial software harpoon (mesher) and ansys fluent (solver). The methodology aims to simulate the flow accurately around complex geometries at relevantly high Re numbers for use in industrial applications, within an acceptable computational time. Geometric differences between the three configurations ensure significant drag changes that have a strong effect on the wake formation behind the vehicle. Therefore, this paper focuses on the analysis of the base wake region. At first, the paper evaluates the performance of the DDES, where it verifies the different operating conditions of the flow around the vehicle with respect to the DDES definition. In a second step, the numerical results are correlated with force measurements and time-averaged flow field investigations, conducted in the Volvo Cars aerodynamic wind tunnel (WT). The comparison confirms a good agreement between the experiments and the simulations. The resolved flow scales obtained by DDES give a further insight into differences in the wake flow characteristics between the configurations related to their contribution to drag.

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