Blunt Trailing Edge Research Articles

Investigation on transition characteristics of hydrofoil boundary layer based on algebraic local-correlation-based transition modeling model

Hydrofoil shapes are used for the marine turbine blades to capture kinetic energy from water currents effectively. Predicting transitions is a critical concern when studying the hydrofoil boundary layer. This paper analyzed the transitional behavior of the boundary layer in the National Advisory Committee of Aeronautics (NACA) hydrofoil, NACA0009, with a blunt trailing edge using the Algebraic Local-Correlation-based Transition Modeling (Algebraic LCTM) model. First, through sensitivity analysis, the effects of the maximum y+ (the dimensionless distance y to the wall), grid expansion ratio, number of normal and streamlined grids, and timescale on transition prediction were studied. The results indicate that finer y+ value and appropriate grid expansion ratios can improve the accuracy of transition prediction, while the influence of timescale on the prediction results is relatively small within the range of Courant number theory values. Second, further analysis was conducted on the transition prediction performance under different Reynolds numbers. It was found that the model predictions were consistent with experimental values at low Reynolds numbers, but the predicted transition position was advanced at high Reynolds numbers, mainly because of the significant disparity in eddy viscosity coefficients within the free flow field. In the study of leading-edge roughness bands' impact on boundary layer transition for hydrofoil, the introduction of roughness significantly expedited the transition process. The Algebraic LCTM model outperformed the gamma (γ) transition model, reducing prediction errors by 5–40% for boundary layer parameters and maintaining errors between 0.005 and 4% for wake vortex shedding frequency, as opposed to the γ model's 0–23%. The results of this study provide a theoretical basis for hydrofoil design.

Wake Three-Dimensionality of Profiled Blunt Trailing Edge Bodies with Varying Chord Length

This paper investigates experimentally the structure of turbulent blunt trailing edge body wakes with varying boundary-layer thicknesses controlled through the freestream velocity and the chord length. The intrinsic effect of transition to turbulence on the vortex-shedding frequency, strength, and its three-dimensional structure is explored. At large-scales, the vortex shedding is characterized by significant phase variations along the span, which vary stochastically and are punctuated by vortex dislocations when the phase differences grow large. These features of the vortex shedding are quantitatively examined in a streamwise–spanwise plane of the wake with particle image velocimetry. When the point of transition shifts upstream due to an increasing Reynolds number, greater phase variations in the vortex shedding along the span and more frequent dislocation events are produced. These changes are linked to the spanwise correlation of the streamwise velocity in the wake. In the turbulent boundary-layer regime, it is found that the phase drift does not change significantly. The decline in the spanwise correlation with increasing boundary-layer thickness in this regime is instead linked to the relative strength of the vortex shedding compared to the random turbulent fluctuations in the wake.

Wake Dynamics of Complex Turning Vanes Using Time-Resolved Particle Image Velocimetry Measurements

Abstract The use of turning vanes spans multiple engineering disciplines such as aerospace, ocean, and biomedical to effectively turn an otherwise uniform flowfield and achieve desired downstream flow angles. The presented work investigates the wake dynamics generated by sets of complex turning vanes which contained nonaxisymmetric geometries, spanwise variations in turning angle, and multiple vane junctions. Time-resolved particle image velocimetry (TR-PIV) measurements were performed to collect three-component velocity data downstream of the vane pack geometries. As the vanes contained blunt trailing edges (TEs), large-scale periodic structures (von Kármán vortices) dominated the unsteady wakes. Two postprocessing methods, proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD), were employed to extract the wake energy or enstrophy content, corresponding spatial modes, and associated frequencies. This was completed for various parameters such as Reynolds number, vane turning angle, and vane trailing edge thickness. Spatial POD analyses showed that zero-turning vanes contained similar dynamics to that of a circular cylinder, and the total wake energy distributions were affected by freestream velocity. A spectral POD analysis in the wake of vane junctions found that the junction flow contained significant coherent content and gave some insight into the mean flow. Finally, vane parameters such as turning angle and TE thickness were found to play a large role in modifying the enstrophy content of the large-scale shedding modes.

Performance enhancement of a semi-active flapping foil energy harvester via airfoil with modified trailing edge and jet flap

This paper aims to numerically study effectiveness of the use of a suitable combination of an airfoil with modified trailing edge and jet flap in enhancing the energy harvesting performance of a semi-active flapping foil. The configuration of the proposed airfoil is created by referring to the method of generating a blunt trailing edge airfoil. The most promising airfoil profile is obtained by only thickening the rear part of the original airfoil to reach a thickness of 2% chord, which can apparently promote the energy capturing capability of a semi-active flapping foil when compared with its conventional counterpart with a sharp trailing edge airfoil. Furthermore, a jet flap, an active flow control technique, is then applied on the aft portion of the modified airfoil and the effectiveness of this combination is assessed by a comparison with that of the passive flow control device, Gurney flap. The present findings suggest that this combination can be much more effective than a Gurney flap in significantly increasing the energy harvesting efficiency of the semi-active flapping foil over a wide range of operating conditions, and also has the advantage of structural integrity, which make it more suitable for harsh environment applications.

Hybrid LES/RANS Simulations of Compressible Flow in a Linear Cascade of Flat Blade Profiles

The paper reports on 3D numerical simulations of unsteady compressible airflow in a blade cascade consisting of flat profiles using a hybrid LES/RANS approach including a transition model. As a first step towards simulation of blade flutter in turbomachinery, various incidence angle offsets of the middle blade were modeled. All simulations were run for the flow regime characterized by outlet isentropic Mach number Mis=0.5 and zero incidence. The results of the LES/RANS simulations (pressure and Mach number distributions) were compared to a baseline RANS model, and to experimental data measured in a high-speed wind tunnel. The numerical results show that both methods overpredict flow separation taking place at the leading edge. In this regard, the hybrid LES/RANS method does not provide superior results compared to the traditional RANS simulations. Nevertheless, the LES/RANS results also capture vortex shedding from the blunt trailing edge. The frequency of the trailing edge vortex shedding in CFD simulations matches perfectly the spectral peak recorded during wind tunnel measurements.

Numerical investigation of the cavitation effects on the wake dynamics behind a blunt trailing edge hydrofoil

The influence of cavitation on the wake behind a NACA 0009 hydrofoil with a truncated trailing edge has been numerically investigated using a homogeneous mixture model coupled with a controlled decay SST γ-Reθt turbulence model. Using optimal definitions of the inlet turbulent intensity and the empirical condensation and vaporization coefficients of the cavitation model, simulated results have shown a good agreement with experimental data. Notably, the numerical results exhibit negligible deviations of less than 0.7% in vortex shedding frequencies for different cavitation levels. If the size of the vortex cavitation grows, a substantial increase in both lift and drag coefficients on the hydrofoil is observed. Furthermore, the influence of cavitation on the trajectories of vortex centers and the morphology of the primary shedding vortices has been revealed using a vortex identification method. The findings highlight that the cavitation development enhances the advected velocity of the shedding vortices while decreasing the streamwise inter-vortex spacing. Consequently, both factors are found to contribute to the increase of the vortex-shedding frequency behind the NACA 0009 hydrofoil with the truncated trailing edge when cavitation appears and develops.

Noise Control of Blunt Flat-Plate Using Slit and Dielectric Barrier Discharge Plasma

This paper investigates the combination of a slit at the blunt trailing edge of the flat plate and dielectric barrier discharge plasma to control the vortex shedding of the plate and its associated tonal noise. The noise and flow characteristics of the plate were measured using a far-field microphone array and the particle image velocimetry technique, respectively. The results show that the vortex shedding and the tonal noise can be significantly suppressed by the slit alone, with an average noise reduction of approximately 10 dB in the test Reynolds number. In addition, installing a plasma actuator inside the slit further suppresses the vortex shedding and reduces tonal noise. However, the additional control efficiency of the plasma decreases with increasing wind speeds, with a further 8 dB reduction at a wind speed of U∞=10 m/s (corresponding to an inducing blowing rate BR of 4.5%). However, only an additional 1.5 dB noise reduction is achieved at U∞=20 m/s (BR=2.25%). The particle image velocimetry snapshots were analyzed by proper orthogonal decomposition. The measurements clearly show the variation in vortex shedding at the trailing edge of the plate, revealing the underlying flow mechanisms that lead to the observed noise variations and frequency changes.

Optimal Design of Anti-Icing Blunt Trailing-Edge Wind Wheel for H-Type Vertical Axis Wind Turbine Under Operating Conditions

Abstract A novel optimization method is developed for the design of an anti-icing blunt trailing-edge wind wheel of H-type vertical axis wind turbine (VAWT) based on the quasi-steady-state icing. The parametric expression of the airfoil is given using the mean camber and thickness functions, the blunt trailing-edge is constructed by the rotation and zoom of coordinates, and then through the aerodynamic design theory, the geometry control equations of the blunt trailing-edge wind wheel are established. The icing process using Solution and Icing modules is repeated at equal interval azimuths to obtain the ice on the wind wheel per revolution. The optimization model is solved using particle swarm optimization (PSO) algorithm integrated with computational fluid dynamics (CFD) method to maximize the wind energy utilization in both ice-free and icing conditions. Significant improvements are realized for flow and aerodynamic characteristics, confirming that the optimization method provides important guidance for an anti-icing design of VAWT blades.

Mode decomposition and simulation of cloud cavity behaviors around a composite hydrofoil

Numerical investigation of the cavity dynamics around a composite hydrofoil with a blunt trailing edge in the cloud cavitating flow is carried out using a tightly coupled fluid–structure interaction method. The hydrofoil is made of a carbon-fiber-reinforced polymers with a ply angle of −45∘(CFRP −45). The results of a stainless-steel hydrofoil with the same geometry and conditions are used as a reference. Simulation results have been validated carefully against experimental data. Several fundamental mechanisms are dictated through simulation results and mode decomposition, including the multistage shedding process, the influence of the bend–twist coupling effect on cavity behaviors, cavitation–vortex interaction, and kinematics of coherent structures. The main reason for the generation of a secondary re-entrant jet is that the primary cloud cavity collapse leads to high pressure, which spreads to the residual sheet cavity closure and then induces a high-pressure gradient. The negative bend–twist coupling effect causes the CFRP −45 hydrofoil to exhibit a smaller cloud cavity scale and non-uniform re-entrant jet strength in the spanwise direction compared to the stainless-steel hydrofoil. Modal decomposition via proper orthogonal decomposition and dynamic mode decomposition indicates that the dominant coherent structures in the cloud cavitating flow include the large-scale cloud cavity, rotating structures due to the re-entrant jet, attached cavity, and small-scale vortex in the wake. The results obtained in this study provide physical insight into the understanding of the mechanisms relevant to complex cloud cavitating flow around a composite hydrofoil.

Computational and Experimental Investigation of FX 63-137 Airfoil at Low Reynolds Numbers

In this study, the capability of the present day RANS based CFD solver in predicting the characteristics of the FX 63-137 airfoil at a low Reynolds number is carried out. The Reynolds number considered in the present work varies between 0.08 to 0.2 million. Computational simulations were carried out on both sharp trailing edge and blunt trailing edge FX 63-137 airfoils. The comparison between the two FX 63-137 airfoils brings out the effect of the trailing edge on the aerodynamic coefficients. Experimental tests were conducted on the FX 63-137 airfoil for these low Reynolds numbers at the MART facility of CSIR-NAL to validate the CFD simulations. Further, the present MART tunnel data is compared against the experimental data available in the literature. This comparison will show the differences in the experimental results between the tunnels and how the CFD simulations compare against them.

Aerodynamic noise reduction of a blunt flat plate by trailing-edge blowing

This study investigates the influence of air blowing on the aerodynamic noise generated by a flat plate with a blunt trailing edge. The uniform blowing was applied through evenly spaced holes along the span at the base of the flat plate. Acoustic pressure measurements were conducted in an anechoic wind tunnel using a free-field microphone at Reynolds numbers ranging from 2.8×105 to 6.5×105. Particle image velocimetry measurements were performed to obtain time-resolved evolution and statistics of the flow velocity field, providing a detailed understanding of the noise reduction mechanisms. The results demonstrated that air blowing effectively reduces both the amplitude and bandwidth of tonal and broadband noise within a limited frequency range. This phenomenon was attributed to the stabilization of separated shear layers over a longer distance by air blowing and a decrease in turbulent kinetic energy in the near-wake region. It was shown that air blowing suppresses the tonal peak of vertical velocity fluctuations and narrows the wake width, which accounts for the increase of vortex shedding frequency and a potential drag reduction. Generally, the effects of air blowing on vortex shedding at the blunt trailing edge are analogous to those of a splitter plate. The unaffected convective velocity of the large-scale vortex structures and the enhanced spanwise coherence in the vortex formation region provide further evidence to this analogy.

Wave effects on the hydroelastic response of a surface-piercing hydrofoil. Part 1. Fully wetted and ventilated flows

This work describes the effects of waves on the hydroelastic response of a hydrofoil in fully wetted and ventilated flows. In the absence of vaporous cavitation (described in Part 2 of this paper series), shallow long-period non-breaking waves delayed ventilation inception because velocity fluctuations prevent the formation of a stably separated region of flow at the foil's leading edge. Aerated von Kármán vortex shedding occurred from the blunt trailing edge, producing vortex-induced vibration of the hydrofoil at a near-constant Strouhal number. Regular waves led to near sinusoidal oscillations of the load and deformations at the wave encounter frequency, while the mean response and the dynamic response at other frequency peaks corresponding to hydrodynamic and structural modes remained mostly unaffected. Significant dynamic load amplification was observed at a submerged aspect ratio of 2 for cases with low angles of attack because of coalescence between the second and third wetted structural modes; at high angles of attack, the amplitude of the load fluctuations and flow-induced vibrations reduced because energy was diverted away from the coalescence frequencies to the nearby vortex shedding frequency. In both calm water and wave conditions, transition from fully wetted to fully ventilated flow resulted in sudden and significant reduction in the load coefficients, as well as foil deflections. An impulse-like signature was observed in the time-frequency spectra during these transitions. In many of the cases, transition to fully ventilated flow also led to substantially reduced amplitudes in the load and deformation fluctuations.

Effect of Wavy Leading Edges on Airfoil Trailing-Edge Bluntness Noise

Among the several noise-generation mechanisms of airfoil self-noise, trailing-edge bluntness noise is an important noise source, which is caused by the vortex shedding at blunt trailing edges. A numerical study on airfoil trailing-edge bluntness noise control using the bio-inspired wavy leading edges is presented in this paper. The high-fidelity, improved, delayed, detached eddy simulation (IDDES) method was used to calculate the flow field, and the acoustic analogy method was used for noise prediction. For both the blunt-trailing-edge airfoils, a baseline airfoil with a straight leading edge and a bio-inspired airfoil with a wavy leading edge were used in this study. The chord-based Reynolds number was 400,000, and there was no angle of attack. The numerical results show that the trailing-edge bluntness noise of the baseline airfoil was significantly reduced by the wavy leading edges. The sound pressure level reduction was about 3.7 dB at the characteristic frequency, and the maximum sound pressure level reduction was as high as 35 dB. The trailing-edge bluntness noise was decreased at all directional angles. The maximum overall sound pressure level reduction was 6.3 dB at 0°. In addition, by analyzing the pressure fluctuations, wake characteristics, turbulent vortex structures and spanwise correlation and coherence of the flow field, the noise-reduction mechanisms of the bio-inspired airfoil are deeply revealed.

Structured porous blunt trailing edge with uniform and non-uniform parameters for vortex shedding noise reduction

Aiming at reducing the blunt trailing edge noise of flat plate, three-dimensional structured porous media with uniform and non-uniform porosities are designed. Acoustics and flow measurement using far-field microphone and particle image velocimetry (PIV) respectively have been implemented in the anechoic wind tunnel to investigate the mechanisms of noise reduction and flow manipulation. The chord-based inflow Reynolds numbers range from 4.8 × 105 to 1.5 × 106. The present work reveals that the regularized structured porous media could provide an effective noise reduction for the blunt trailing edge of flat plate similar to conventional randomized porous media (e.g. metal foam). When the uniform porosity is larger than 0.73, the tonal noise is suppressed significantly and the overall sound pressure level is decreased by 10 dB at least. However, some unexpected additional noise in the mid-to-high frequencies (1500–9000 Hz) occurs, which is associated with primary flow interactions inside the pore structures (cavity resonance). Further, four non-uniform porosity cases are studied to explore the optimization of porosity distribution. Not only is the tonal noise significantly reduced but also the additional noise is lower than that of uniform cases, which indicates that non-uniform porosity has more potential advantages for noise reduction. It is interestingly discovered that for the non-uniform porous trailing edge, the volume-average porosity and distribution trend play important roles respectively in suppressing the tonal noise and the additional mid-to-high-frequency noise. The PIV results demonstrate that 3D printed structured porous media can significantly weaken the vortex intensity of the shear layer and delay the generation of vortex shedding downstream, which are the critical underlying mechanisms for noise reduction. The porosity of uniform cases and the volume-average porosity of non-uniform cases are closely associated with the vortex shedding and the high-values benefit of suppression. And the analysis of wake velocity spectrum indicates that the additional noise is not correlated to the wake flow, but the cavity resonance might be the main reason.

Study on the repair parameters for trailing‐edge bonding failure of wind turbine blade in service

AbstractA numerical analysis method of trailing edge deboning is proposed in this paper. Using this method, multiple repair parameters can be quantified by analyzing aerodynamic responses and structural characteristics of the trailing edge. This method can be applied to three types of trailing edge, including blunt trailing edge, transitional trailing edge, and pointed trailing edge. In this study, the repair parameters are divided into two types, including the internal parameters that can affect the bonding strength and the external parameters that can affect the stiffness and aerodynamic shape. The main research steps are as follows: First, a repair structure shell‐body model was developed. Second, static tensile tests were carried out using 49 specimens, covering two lap joint types and seven bonding thicknesses. Finally, nine different repaired trailing edge models were developed using Ansys/Fluent for each two two‐dimensional airfoil. A 30–40 m section of a 71 m blade was used to develop a three‐dimensional (3D) rotating model with the repaired trailing edge. The simulation results show that the two internal parameters, overlap length and the slope of adhesive joints, are the key to improving the bonding performance of the pointed trailing edge. In addition, the bonding thickness range of 1–10 mm is proved by the experiment results and numerical analysis to be sufficient for good bonding performance. Besides this, the influence of the repair height on the aerodynamic pressure distribution and lift coefficient is much greater than the repair width, and the torque and power of the repaired 3D blade model are 1.91% higher than that of the original blade. This should further help provide an effective theoretical basis for determining the repair plan for a wind turbine blade.

Parametrical study on separation-induced transition and vortex dynamics of a reversed pitching airfoil

The pitching airfoils, applied to the vertical axis turbines and propellers, are critical to extract more energy from the environment. At retreating side, when the airfoil blunt leading edge becomes the trailing edge, the transition and vortex dynamics are quite different from that at advancing side. The goal of the present work is to investigate the transition and vortex evolution over the reversed pitching airfoil, with main focus on the parametrical effect, including the mean pitching angle and pitching amplitude, reduced frequency and Reynolds number. The main results show that the flow structure on the reversed airfoil is more complex compared with that over the forward airfoil due to the earlier flow separation near the sharp leading edge. Then, the transition on the reversed airfoil firstly occurs within the separated shear layer near the sharp leading edge, and then the flow reattaches, leading to the generation of the leading-edge vortex. Near the blunt trailing edge, the second transition appears on two sides, resulting in the asymmetrical boundary layer as the incidence increases continuously. This event is totally different from that on the forward airfoil, shown by the transition always moving from the trailing edge to the leading edge. The flow unsteadiness of the reversed airfoil is mainly induced by the separated shear layer and leading-edge vortex, which is greatly affected by different parameters. Besides, the trajectory of some specific vortices also depends on the working conditions significantly. It is believed that this work can deepen the understandings of underlying flow physics of the reversed airfoils.

Flow and Noise Characteristics of Blunt-Trailing-Edge Flat Plate with an Upstream Cylinder

This paper experimentally studies the flow interaction and the associated noise between an upstream cylinder and a downstream finite-chord-length flat plate with a blunt trailing edge in an acoustic wind tunnel. The configuration of this cylinder–plate model varies by changing the cylinder diameter and the vertical gap between the cylinder and the flat-plate surface. Aerodynamic noise was measured using far-/near-field microphone arrays. The results show that, as compared to the single flat plate, the trailing-edge noise associated with the vortex shedding from the flat plate is significantly suppressed when the gap is : that is, when the cylinder is vertically close to the flat-plate surface. In addition, the corresponding vortex shedding frequency decreases visibly. The leading-edge interaction noise due to the cylinder wake impingement gradually loses its dominance with the increase of the vertical gap. Compared to the single cylinder, the vortex shedding frequency from the upstream cylinder in the cylinder–plate model is reduced slightly due to the acoustic feedback from the plate leading edge. Flow characteristics were measured using surface microphones and particle image velocimetry (PIV) techniques. The pressure fluctuations along the plate surface present the dominant frequencies at the leading edge and the trailing edge, respectively, and verify the changes in the peak frequency and its noise level. The PIV technique clearly shows the variation of the vortex–body interaction at the leading edge and the vortex shedding at the trailing edge, revealing the underlying flow mechanism responsible for the observed noise changes and frequency shifts.

The Effect of Trailing Edge Profile Modifications to Fluid-Structure Interactions of a Vertical Axis Tidal Turbine Blade

Renewable energy has become an essential energy alternative since the continual depletion of non-renewable energy resources and increasing environmental issues. Tidal energy is a promising future renewable resource which can be extracted using a vertical axis tidal turbine. Since it was proposed, a tidal turbine performance requires improvements which can be obtained by a blade’s trailing edge modification. Modifying the blade’s trailing edge profile is confirmed to be one way to improve a turbine’s work. However, the influence of a trailing edge modifications on a vertical axis tidal turbine blade’s interaction with fluid has not been fully understood, thus the fluid induced vibration as the fluid behaviour working on a vertical axis tidal turbine blade has not been completely discovered. In this paper, 2D fluid-structure interactions of modified vertical axis tidal turbine blades are examined and modelled using OpenFOAM. Three different modified blade profiles are proposed: sharp, rounded, and blunt. The modified profiles are employed to an original NACA 0012 blade and their influences on a vertical axis tidal turbine blade interaction are observed. The result discovers the fluid behaviour and fluid-induced vibrations at all positions (represented by 12 positions) over one turbine’s cycle. The results demonstrate the frequency domain blade velocities and time domain blade displacements for all modified blades. The fluid behaviour around the blade is confirmed by pressure distribution plots over the blade’s upper and lower surfaces. The results show that the blunt profile provides less frequent vibrations due to a reducing vorticity in the downstream fluid regime. However, the vibration amplitude that occurs on the blunt blade is higher than those of rounded and sharp profiles. Based on this research, the blunt trailing edge profile appears to be more favourable to be applied and used for vertical axis tidal turbine blades.

Influence Analysis of Simulation Parameters on Numerical Prediction of Compressible External Flow Field Based on NACA0012 Airfoil under Hypersonic Speed

Currently, the influence of numerical parameters on the prediction accuracy of the compressible external flow field characterized by a NACA0012 airfoil under hypersonic speed, especially the influence analyses of the trailing edge shape, the modeling methods, and the adopted data points on it are relatively sparse. In this paper, using three modeling approaches and two data point sources, six NACA0012 airfoils are designed including two types of trailing edge shapes. Unlike under the incompressible external flow field, the comparative analysis shows that though the optimal accuracy is obtained by the sharp trailing edge, the improper sharp trailing edge design could result in a greater error ratio than that of the blunt trailing edge. Similarly, the definition formula could provide the best performance, while in other cases, NACA4 is preferred and the selection between them depends on the adopted data point source. Furthermore, the increase in the number of the adopted two types of data points would lead to a decrease in prediction accuracy. According to the comparison among all the optimal total error ratios, the suggested configuration is the sharp trailing edge based on the definition formula adopting 200 points sourced from NACA4 + 16 m far-field distance + SA turbulence model + ROE flux type and the best result is 2.05%.

Aerodynamic and Acoustic Simulations of Thick Flatback Airfoils Employing High Order DES Methods

AbstractThe results of high fidelity aerodynamic and acoustic computations of thick flatback airfoils are reported in the present paper. The studies are conducted on a flatback airfoil having a relative thickness of 30% with the blunt trailing edge thickness of 10% relative to chord. Delayed Detached‐Eddy Simulation (DDES) approaches in combination with high order (5th) flux discretization WENO (Weighted Essentially Non‐Oscillatory) and Riemann solver are employed. Two variants of the DES length scale calculation methods are compared. The results are validated against experimental data with good accuracy. The studies provide guideline on the mesh and turbulence modeling selection for flatback airfoil simulations. The results indicate that the wake breakdown is strongly influenced by the spanwise resolution of the mesh, which directly contributes to the prediction accuracy especially for drag force and noise emission. The Reynolds normal stress and the Reynolds stress component have the largest contributions on the mixing process, while the contribution of the component is minimal. Proper orthogonal decomposition is further performed to gain deeper insights into the wake characteristics.