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.

LES and Hybrid RANS/LES of a Fundamental Trailing Edge Slot

2014 ◽  
Author(s):  
Elizaveta Ivanova ◽  
Gregory M. Laskowski
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Numerical Study ◽  
Mixing Layer ◽  
Detached Eddy Simulation ◽  
Trailing Edge ◽  
Adiabatic Wall ◽  
Mean Velocity ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

This paper presents the results of a numerical study on the predictive capabilities of Large Eddy Simulation (LES) and hybrid RANS/LES methods for heat transfer, mean velocity, and turbulence in a fundamental trailing edge slot. The geometry represents a landless slot (two-dimensional wall jet) with adjustable slot lip thickness. The reference experimental data taken from the publications of Kacker and Whitelaw [1] [2] [3] [4] contains the adiabatic wall effectiveness together with the velocity and the Reynolds-stress profiles for various blowing ratios and slot lip thicknesses. The simulations were conducted at three different lip thickness and several blowing ratio values. The comparison with the experimental data shows a general advantage of LES and hybrid RANS/LES methods against unsteady RANS. The predictive capability of the tested LES models (dynamic ksgs-equation [5] and WALE [6]) was comparable. The Improved Delayed Detached Eddy Simulation (IDDES) hybrid method [7] also shows satisfactory agreement with the experimental data. In addition to the described baseline investigations, the influence of the inlet turbulence boundary conditions and their implication for the initial mixing layer and heat transfer development were studied for both LES and IDDES.

Experimental and Numerical Investigations of the Heat Transfer and Flow Field in a Trailing Edge Cooling Geometry: Part 2 — LES and Hybrid RANS/LES Study

2015 ◽  
Author(s):  
Elizaveta Ivanova ◽  
Gustavo Ledezma ◽  
Guanghua Wang ◽  
Gregory M. Laskowski
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Future Research ◽  
Detached Eddy Simulation ◽  
Trailing Edge ◽  
Validation Data ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Adiabatic Cooling ◽  
Les Model

This paper presents the results of a numerical study on the predictive capabilities of Large Eddy Simulation (LES) and hybrid RANS/LES methods for heat transfer in the trailing edge (TE) geometry experimentally investigated in Part 1. The experimental validation data includes 2D wall contours and laterally-averaged values of adiabatic cooling effectiveness. The simulations were conducted at three different blowing ratio values. The comparison with the experimental data shows a general advantage of LES and hybrid RANS/LES methods against steady-state RANS. The results obtained by means of the WALE LES model and the Improved Delayed Detached Eddy Simulation (IDDES) hybrid RANS/LES method were comparable. The presented grid dependence study shows the importance of adequate grid resolution for the predictive capabilities of trailing edge cooling LES. Furthermore, the importance of considering TE slot lands simulation quality in the numerical method assessment is discussed. Potential directions of future research needed to improve simulation reliability are outlined.

Turbulence modelling techniques for aeroelastic problems: results and comments from the Second AIAA Aeroelastic Prediction Workshop

2017 ◽  
Vol 89 (5) ◽  
pp. 683-691 ◽  
Author(s):  
Marcello Righi
Keyword(s):  
Navier Stokes ◽  
Test Case ◽  
Detached Eddy Simulation ◽  
Special Flow ◽  
Content Type ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Large Eddy ◽  
Modelling Techniques

Purpose The quality of aeroelastic predictions strongly depends on the quality of aerodynamic predictions. At the boundary of a typical flight envelope, special flow conditions may arise, which challenge the conventional Reynolds-averaged Navier–Stokes (RANS) approach beyond reasonable limits. Design/methodology/approach Test Case 3 of the Second AIAA Aeroelastic Prediction Workshop is a representative test case, where the flow over a supercritical wing separates downstream of the shock waves and generates large turbulent lengthscales. Findings In this study, RANS predictions are compared to those obtained in this particular test case with the more sophisticated hybrid RANS–large eddy simulation (LES) approach, in particular with the Spalart–Allmaras–delayed detached eddy simulation model. Results are indeed closer to experimental data. Originality/value However, the costs associated with this approach are much higher. It is argued that adopting hybrid RANS–LES modelling is not a simple model switch.

Impact of the trailing edge shape of a downstream dummy vehicle on train aerodynamics subjected to crosswind

2020 ◽  
pp. 095440972091503 ◽  
Author(s):  
Xiaoshuai Huo ◽  
Tanghong Liu ◽  
Miao Yu ◽  
Zhengwei Chen ◽  
Zijian Guo ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Detached Eddy Simulation ◽  
Trailing Edge ◽  
Wind Tunnel Tests ◽  
Eddy Simulation ◽  
Pressure Distributions ◽  
Delayed Detached Eddy Simulation ◽  
Yaw Angle ◽  
Train Aerodynamics ◽  
The Impact

Wind tunnel tests for trains under large yaw angles are usually limited due to the width of the wind tunnel. Therefore, the leading car and a downstream dummy vehicle model are often employed instead of a real train, but there are no clear regulations regarding the shape of the end of the dummy vehicle. This paper studied the impact of the trailing edge shape of the downstream dummy vehicle on train aerodynamics subjected to crosswind based on the shear-stress-transport k-ω turbulence model of the delayed detached eddy simulation. Three types of end shapes, namely the rectangular end shape, the arc end shape, and the streamlined end shape were chosen for comparison, and the simulation results of the three-car-group train were selected as the benchmark. First, the reliability of the numerical method was validated by wind tunnel tests. Then, the aerodynamic coefficients under yaw angles of 0°–60° and the surface pressure distributions and flow structures around the train under the yaw angle of 60° of the head cars with different end shapes were compared and analyzed.

Low-Memory Reduced-Order Modelling With Dynamic Mode Decomposition Applied on Unsteady Wheel Aerodynamics

2017 ◽  
Author(s):  
Marco Kiewat ◽  
Lukas Haag ◽  
Thomas Indinger ◽  
Vincent Zander
Keyword(s):  
Rotation Frequency ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
Test Case ◽  
Detached Eddy Simulation ◽  
Weighting Method ◽  
Reduced Order ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Mode Decomposition

Wheel aerodynamics has a major impact on the overall aerodynamic performance of a vehicle. Different vortex excitation mechanisms are responsible for the induced forces on the geometry. Due to the high degree of complexity, it is difficult to gain further insight into the vortex structures at the rotating wheel. Therefore, wheel aerodynamics is usually investigated using temporally averaged flow fields. This work presents an approach to apply a recently introduced low-memory variant of Dynamic Mode Decomposition (DMD), namely Streaming Total DMD (STDMD), to investigate temporally resolved simulations in greater detail. The performance of STDMD is shown to be comparable to conventional DMD for a rotating generic closed wheel simulation test case. By creating a Reduced-Order Model (ROM) using a comparably small amount of DMD modes, the amount of complexity in the flow field can be drastically reduced. Orthonormal basis compression, amplitude ordering and a newly introduced amplitude weighting method are analyzed for creating a suitable ROM of DMD modes. A combination of compression and ordering by eigenvalue-weighted amplitude is concluded to be best suited and applied to the Delayed Detached Eddy Simulation (DDES) of the rotating generic closed wheel and a production vehicle rim wheel. The most dominant flow structures are captured at frequencies between 18Hz and 176Hz. Leading modes for both geometries are found close to the wheel rotation frequency and multiples of that frequency. The modes are identified as recirculation modes and vortex shedding.

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