Large Eddy Simulation Technique Research Articles

Prediction and analysis of aeroacoustic characteristics of a real-size high-speed train running in open field using compressible Large Eddy Simulation and vortex sound source

With the rapid advancement of technology, high-speed trains have been requested to increases their speeds. Aerodynamic noise generated from the external flow fields around these trains has become a critical factor to be addressed during a design phase. Accurate prediction of flow-induced noise in high-speed trains requires high-resolution sound source generation in the near-field and precise noise propagation analysis in the acoustic field without numerical dissipation. This necessitates the appropriate design of grids, taking into account aerodynamic noise generation and propagation in conjunction with the length scales of the relevant components of a real-size train. To tackle this challenge, the present research employs a three-dimensional compressible Large Eddy Simulation (LES) technique with high-resolution grids to simultaneously calculate the external flow and acoustic fields of a real-size high-speed train consisting of five cars running in an open field. A comprehensive analysis is conducted to evaluate the contributions of major components, namely, a cap, pantograph, bogie, intercoach, and HVAC cover, which are well-known as significant contributors to high-speed train flow-induced noise. The study utilizes the vortex sound source approach to analyze the generation mechanism of flow-induced noise for each component, providing valuable insights that could potentially aid in reducing aerodynamic noise.

On the coupling between wall-modeled LES and immersed boundary method towards applicative compressible flow simulations

The current work presents an innovative numerical technique for high-Reynolds/high-Mach number compressible flow simulations in complex configurations. In particular, the research combines a novel wall-modeled large-eddy simulation technique with a sharp-interface immersed boundary method in the framework of high-order numerical schemes. The proposed approach enables the best from wall modeling and the immersed boundary. The first is concerned with accurately dealing with wall flows while avoiding direct control of near-wall resolution; the second is related to efficiently treating arbitrarily complex geometries in Cartesian grids. In particular, the paper extends a well-established wall model already presented by the research group to arbitrarily-shaped bounds. The method yields a minimally invasive technique that switches between wall-resolved and wall-modeled large-eddy simulations according to the local near-wall resolution. Thus, easily fitting aerodynamic simulation needs. After discussing the numerical procedure, the paper provides several benchmarks to demonstrate the validity of the proposed approach. In particular, literature-available direct numerical datasets are mined to compare acquired outcomes. The results’ accuracy is found to be remarkable from low-Mach-channel and -pipe flow configurations up highly-compressible flows concerning the spatial deployment of the boundary layer over a flat plate and the shock-wave/boundary-layer interaction over a compression ramp. Thus, the proposed method appears to be a promising framework for dealing with engineering-relevant flow simulations along with the efficient path of Cartesian meshes combined with massively parallel GPU-accelerated architectures.

Flow Around a Pile Under Highly Non-linear Waves Using an Unstructured Finite-Volume Technique

This study has coupled a wave generating model with the existing in-house 3D Large Eddy Simulation (LES) hydrodynamic model. The primary focus is to simulate the hydrodynamics around a circular cylinder under non-linear waves. To accurately capture the behaviour of non-linear waves, a relaxation method is implemented on an unstructured grid, and its effectiveness is examined in a numerical wave tank with a vertical cylinder. To validate the accuracy of the proposed model, we compare the simulation results with experimental data, specifically analysing the transmission of the wave surface across the cylinder and examining the phased-averaged pressure distribution. The simulations also consider the shedding of lee-wake vortices, and the results are extensively discussed. Significantly, this paper represents the first known investigation of hydrodynamics under non-linear waves using the large-eddy simulation technique on unstructured grids. This approach opens up new possibilities for studying complex wave-structure interactions with improved accuracy and realism.

CFD simulation of an axial discharge rotor-stator mixer: LES versus RANS predictions

The large eddy simulation (LES) technique is used to model the turbulent flow of water in a two-stage, axial discharge, in-line rotor-stator mixer. The WALE sub-grid scale model is employed, and the resulting filtered velocity field is ensemble averaged to predict the mean velocity, turbulent kinetic energy, energy dissipation rate, and energy production rate. The results of these 3-D sliding mesh simulations are compared to analogous RANS predictions on similar meshes using the realizable k-ε turbulence model. Stator slot flow rate and rotor torque/power draw are also monitored. RANS and LES predict similar mean velocity profiles, flow rate and rotor torque. LES predicts higher turbulent kinetic energy, but lower dissipation rate compared to RANS. Results from a coarse and refined computational mesh are compared to discuss the significance of resolving smaller scales for LES. The effect of operating conditions on throughput, power draw, and other quantities of practical utility are also discussed. It was found that prediction of macroscopic quantities such as flow rate and power draw can be done efficiently using either RANS or LES on a relatively course mesh while capturing turbulence quantities requires a well refined LES simulation.

Dispersion of expectorated cough droplets with seasonal influenza in an office

We do not fully grasp viral droplet transmission processes in ventilated interior environments. The core focus of our research is to investigate the effectiveness of the protected occupied zone ventilation (POV) through computational fluid dynamics models in a simplified office setting. The large-eddy simulation technique with the Eulerian–Lagrangian model was implemented to address complicated indoor processes such as turbulence, flow–aerosol interaction, and ventilation impact. We computationally investigated the effects of desk partitions and the POV on cough droplets in an office. The ventilation approach was tested using two distinct exhaust layouts and four different ventilation rates (1.0, 1.2, 1.5, and 1.8 m/s). A comparative analysis of the ventilation flow fields, topologies, and particle directions has been studied. The findings indicate that the plane jet's ventilation rates influence the protected occupied zone ventilation performance. The ventilation rates distributed the virus droplets around the room, but compared to the up-exhaust cases, the down-exhaust cases appeared to have better shielded the healthy person. This pattern could indicate that the placement of the exhaust outlet in ventilation systems significantly influences indoor aerosol dispersion. The results also show that substantial flow streams may carry tiny particles (≤70 μm) throughout their path. Large particles (≥100 μm) could not go far in cough gas clouds. Most viral particles deposit on solid surfaces in various work sites per specific ventilation rates. Office workers need to be very cautious around these hazardous areas.

Study on Hydrodynamics of Fish-Friendly Open-Channel Flow

To elucidate the hydrodynamic characteristics of a fish-friendly open channel, a three-dimensional numerical hydrodynamic model is constructed in this study employing the Large-eddy Simulation (LES) technique. The reliability of this numerical model is thoroughly validated by incorporating periodic boundaries in the flow direction, allowing for the recurrent development of water flow within the computational domain and utilizing experimental data from a flume. The results demonstrate that the fish-friendly channel is partitioned into a high-velocity mainstream zone and a low-velocity habitat zone. The time-averaged flow velocity in the mainstream zone is approximately 2.0 times the cross-sectional average flow velocity. In the low-velocity habitat zone, the average hourly flow velocity and turbulence are at a relatively low level, rendering the zone suitable for fish habitation and the incubation of adhesive fish eggs. A significant vortex structure is present in the mixing layer at the junction of the main flow area and the habitat area, which not only markedly increases the turbulence intensity but also serves as the primary driver of momentum exchange within the open channel.

On the robustness and accuracy of large-eddy simulation in predicting complex internal flow of a gas-turbine combustor

The objective of this study is to evaluate the effects of numerical and model setups on the large-eddy simulation (LES) predictive capability for the internal flow of a propulsion-relevant configuration. The specific focus is placed on assessing the LES technique with lower mesh resolutions, which is of technological relevance to practical industrial design. A set of Riemann flux formulations and commonly used subgrid-scale models are considered in this work to produce a hierarchy of LES setups with different dissipation effects (both numerically and physically). The LES results obtained from different setups are compared qualitatively in terms of the key flow characteristics and evaluated quantitatively against the experimental measurements. The error landscape is generated to reveal the predictive qualities of different LES setups. The study shows that the choice of numerical flux formulation plays a prominent role in governing the general flow patterns, while the effect of subgrid-scale model is mainly manifested in transient flow characteristics, such as vortex breakdown and swirl-induced vortical structures. Based on the error analysis, it is found that lower dissipative LES setup is not always beneficial to the LES accuracy. This is in contrast to the commonly accepted understanding in literature for the LES, which was established solely with canonical flow configurations.

Passively enhanced VIV responses of side-by-side cylinders at moderate Reynolds number

Stationary upstream cylinders were used to enhance the response of vortex-induced vibration (VIV) of side-by-side (SBS) cylinders at Reynolds number Re = 1000. A modified direct-forcing immersed boundary (DFIB) with a large eddy simulation (LES) technique was employed to get the numerical solution. The VIV responses and VIVACE (vortex-induced vibration for aquatic clean energy) efficiency were investigated for various reduced velocities (UR∗) at a constant mass-damping (m∗ζ). Furthermore, the influence of diameter (d∗) and spacing (s∗) of stationary upstream cylinders on the enhancement of amplitude response and VIVACE efficiency were analysed. The optimal upstream cylinder diameter and spacing were d∗ = 0.4 - 0.6 and s∗⩽ 0.4. Within these ranges, the enhancement of amplitude response and efficiency was observed for UR∗⩾ 5.0, while the decrease in amplitude response and efficiency for UR∗ = 4.0 – 4.5 was minimized.

Effects of various backward-facing steps on flow characteristics and sediment behaviors

The study of flow over various steps behind the hydraulic structures, such as weirs, dams, spillways, barrages, and flood gates, is still of particular interest to researchers due to the complexity of flow characteristics and sediment behaviors at near-bed region. This study investigates the effect of various inclined backward-facing step (BFS) angles on near-bed turbulent flow structures and bedload transport rate in surface jet flow regime. A combined numerical technique of large eddy simulation and discrete element method, based on the open sources package OpenFOAM, is employed. The validation of the numerical model shows a good agreement between the simulation results and observed data obtained from different experiments. The simulation results reveal that the flow does not form a separation zone when the BFS angle is less than 20°, wherein the near-bed turbulence intensity is insufficient to induce substantial sediment movements. As the step angle is increased to a certain value (20°), the separation flow is formed. Consequently, the near-bed turbulence intensity is significantly increased due to the splat effect, and the sediment flux is also drastically increased. As the BFS angle further increases to 30° and 90°, the reattachment length is extended without notable changes in maximum turbulence intensity near the bed. The peaks of the mean bedload transport rate are located further downstream along the extended reattachment length. The quadrant analysis for bedload transport is performed to quantify the interactions between the flow and sediment movement. The results demonstrate that the sweep event plays significant role in moving most sediment to downstream of the reattachment point. On the other hand, right upstream of the reattachment point, the burst becomes the dominant turbulence event to move the majority of the sediment backward in the upstream direction.

On a model-based approach to improve intranasal spray targeting for respiratory viral infections

The nasopharynx, at the back of the nose, constitutes the dominant initial viral infection trigger zone along the upper respiratory tract. However, as per the standard recommended usage protocol (“Current Use”, or CU) for intranasal sprays, the nozzle should enter the nose almost vertically, resulting in sub-optimal nasopharyngeal drug deposition. Through the Large Eddy Simulation technique, this study has replicated airflow under standard breathing conditions with 15 and 30 L/min inhalation rates, passing through medical scan-based anatomically accurate human airway cavities. The small-scale airflow fluctuations were resolved through use of a sub-grid scale Kinetic Energy Transport Model. Intranasally sprayed droplet trajectories for different spray axis placement and orientation conditions were subsequently tracked via Lagrangian-based inert discrete phase simulations against the ambient inhaled airflow field. Finally, this study verified the computational projections for the upper airway drug deposition trends against representative physical experiments on sprayed delivery performed in a 3D-printed anatomic replica. The model-based exercise has revealed a new “Improved Use” (or, IU) spray usage protocol for viral infections. It entails pointing the spray bottle at a shallower angle (with an almost horizontal placement at the nostril), aiming slightly toward the cheeks. From the conically injected spray droplet simulations, we have summarily derived the following inferences: (a) droplets sized between 7–17 μm are relatively more efficient at directly reaching the nasopharynx via inhaled transport; and (b) with realistic droplet size distributions, as found in current over-the-counter spray products, the targeted drug delivery through the IU protocol outperforms CU by a remarkable 2 orders-of-magnitude.

104 Application of CFD Simulation for Development Cyclone Samplers

Abstract Aerosol sampling is one of the largest and growing application areas of small-scale cyclone separators. A series of limit values are already or will be reduced in the future and therefore there is a need for samplers operating at larger flow rates that can collect the required amount of particles for analysis at lower aerosol concentrations. Therefore, the main goal of this work was to develop and validate a Computational Fluid Dynamics (CFD) model that can be used for simulation and optimisation of cyclone samplers. For aerosol flow modelling the Euler-Lagrange method was applied where the continuous phase is treated in an Eulerian manner, whereas the dispersed phase is treated in a Lagrangian approach. For a proper simulation of the flow field, the Large Eddy Simulation (LES) technique was used. A dynamic Smagorinsky-Lilly model was applied to calculate subgrid-scale turbulence. The developed model was validated on two cyclone samplers, a 9.5 mm in diameter sampling cyclone of the HD design and a 23 mm in diameter FSP 10 cyclone. For that, the simulated performance characteristics, such as a cut-size, a slope of the penetration curve, and the pressure drop, were compared with the experimental measurements. The simulation results agree well with experimental data. The deviation in cut-size, the slope of the penetration curve, and the pressure drop between the experimental data and LES simulations of the HD cyclone do not exceed 7%, 18.4%, and 10.3% respectively. Regarding the FSP10 cyclone, the deviations in cyclone performance characteristics are even lower.

Vortex-induced vibration of two circular cylinders in a side-by-side arrangement at moderate Reynolds number: A numerical study

Vortex-induced vibration (VIV) of two transversely vibrating cylinders in a side-by-side (SBS) arrangement is numerically investigated using a combination of direct-forcing immersed boundary and large eddy simulation techniques. The VIV responses of vibrating SBS cylinders at two reduced velocities (UR* = 4.0 and 6.0) are studied for a range of gap ratio 1.0 ≤g*≤ 3.0. Moreover, the influence of mass ratio, damping ratio, and Reynolds number in the amplitude response and efficiency of VIVACE (Vortex-Induced Vibration for Aquatic Clean Energy) from vibrating SBS cylinders are investigated at moderate Reynolds numbers (Re = 1000 and 10 000). The optimal gap ratio for UR* = 4.0 is in the range of 1.0 ≤g*≤ 1.2. Larger than this range, the VIV responses are close to single-cylinder responses. At UR* = 6.0, all gap ratios show lower responses than a single-cylinder case. The vibrating SBS cylinder with a larger damping ratio results in higher maximum VIVACE efficiency with a narrower UR* range for significant efficiency. With almost the same amplitude response, the SBS cylinders with a lower mass ratio result in lower VIVACE efficiency. Using the same mass-damping parameters, it appears that a low mass ratio could be desirable to increase the UR* range of significant VIVACE efficiency and pick the proper damping ratio to reach a high value of maximum VIVACE efficiency. The effect of flow conditions on the amplitude response and VIVACE efficiency of vibrating SBS cylinders with the same VIV parameters is not significant.

On the effects of hybrid surface wettability on the structure of cavitating flow using implicit large eddy simulation

BackgroundSupercavitation flow is characterized by the presence of a supercavity, which can be unstable and cause unwanted motion or even loss of control of an object. To address this issue, flow control techniques are often employed. These techniques aim to manipulate the flow of liquid around the object and improve stability and control. Some of these methods include using control surfaces, injecting fluids, or more advanced techniques such as active flow control or smart materials. MethodThe aim of this study is to use computational methods to investigate the behaviour of supercavitation flow over a Clark-Y hydrofoil with different contact angle patterns (hybrid wettability) inspired by the Namib desert beetle. The hybrid wettability consists of six distinct patterns with a 160-degree contact angle for superhydrophobic surfaces and a five-degree contact angle for superhydrophilic surfaces. To predict the dynamic and unsteady behaviours of the supercavitation flow with a cavity number of 0.4, the implicit large eddy simulation (ILES) technique and Kunz mass transfer model are used. The compressive volume of fluid technique is used in conjunction with dynamic adaptive mesh refinement to track the interface between the vapour and liquid phases. The simulations are conducted using the interPhaseChangeFoam two-phase flow solver within the OpenFOAM framework. This study analyses the time-averaged and instantaneous fluid dynamic properties of the supercavitation flow of the hydrofoil with a hybrid surface, including pressure, velocity, vorticity fields, wake flow, recirculation zone, and liquid volume fraction. In addition, it examines the instantaneous cavity leading edge and flow separation, the vortical flow structure, vorticity stretching and dilatation, spanwise flow details, the creation of a low-pressure zone behind the hybrid hydrofoil, streamwise velocity fluctuations, and the cavity dynamics over an entire cycle. FindingsThe results show that the contact angle has a significant effect on the structure of the supercavitation flow. Specifically, the use of a superhydrophobic surface on the pressure side and trailing edge of a hydrofoil, along with a superhydrophilic surface on the leading edge, can reduce the thickness of the wake zone, the length of the cloud cavity, and flow instability. Additionally, this approach can delay the onset of cavitation.

Large eddy simulation of flow around two side-by-side circular cylinders at Reynolds number 3900

This paper investigates the flow dynamics around two circular cylinders in a side-by-side arrangement with different spacing ratios (T/D, T is the center-to-center cylinder spacing and D is the diameter) under a subcritical Reynolds number condition (Re = 3900). A three-dimensional (3D) numerical model was developed with Large Eddy Simulation (LES) technique. The model was well validated against published data of flow around a single cylinder at Re = 3900. Numerical simulations were conducted for flow around two side-by-side circular cylinders with T/D = 1.2, 1.5, 1.75, 2, 2.5, 3, 3.5, and 4. Based on the LES results, three wake regimes were identified: single bluff body regime (T/D = 1.2), biased flow regime (T/D = 1.5–2), and parallel vortex streets regime (T/D = 2.5–4). In the single bluff body regime with T/D = 1.2, the stable deflection of gap flow is also observed which indicates that there may exist a transition state from the single bluff body regime to the biased flow regime. In biased flow regime, the pairing and merging process of the outer vortices with the inner vortices are analyzed. The occurrence of the flip-flopping phenomenon is found to be related to the merging tendency between gap-side vortices in narrow wake region and free-flow-side vortices in wide wake region, and the relative phase of gap side vortices in transient state. In the parallel vortex streets regime, the phase relation of the vortex shedding process was analyzed. The time proportions of the in-phase mode and anti-phase mode are found to be varied with spacing ratio. As the spacing ratio increases, the wakes behind the cylinders lose their dependency on the anti-phase mode. The results of the present study were compared with the existing results at other Reynolds numbers. It is found that vortex shedding manner during the flip-over transitions is closely related to the spacing ratios and is independent of the Reynolds number.

Turbulent Inflow Generation for Large-Eddy Simulation of Winds around Complex Terrain

Accurate turbulent inflow conditions are needed to broaden the application of the large-eddy simulation technique to predict winds around arbitrarily complex terrain. We investigate the concept of buoyancy perturbations with colored noise to trigger turbulence in upstream flows approaching complex terrain regions. Random perturbations are imposed on the source term in the pseudo-temperature transport equation. These perturbations are effective within three-dimensional boxes and scaled using a bulk Richardson number defined for each box. We apply the turbulent inflow generation technique to predict winds around the Askervein and Bolund Hills under neutrally stratified conditions. We find that a common value for the bulk Richardson number works well for a variety of flow problems. Additionally, we show that the height of the perturbation box plays an important role in the accuracy of the predictions around complex terrain. We consistently obtained good results for both simulation cases when the perturbation box height was made a fraction of the Obukhov length scale.

Modal Decomposition Analysis of Bluff-Body Stabilized Lean Premixed CH4/H2/air Flames Based on LES Data

Unsteady flow and flame dynamics of bluff body stabilized CH4/H2/air premixed flames are investigated numerically with LES and modal decomposition techniques. Energy ranked and frequency dependent modes are identified with proper orthogonal (POD), spectral proper orthogonal (SPOD) and dynamic mode decompositions (DMD). Flow and flame coherent structures are extracted based on the axial velocity and heat release rate contours. Two cases, namely 100% CH4/air (V-flame) and 43.4% CH4 + 56.6% H2/air (M-flame), are selected for the analysis. Each case is acoustically excited in large eddy simulation (LES) with harmonic excitation signals at distinct frequencies and with a broadband excitation signal, to produce snapshots for modal decomposition analysis. In POD, the frequencies of the relevant modes are extracted with the discrete Fourier transform (DFT) of time coefficients, while in SPOD and DMD the extracted modes are frequency dependent by nature. Results are compared and commented.

Aerodynamic noise due to complex internal flow through cordless vacuum cleaner and suction tower station

Although the demands and sales of cordless vacuum cleaner are on the rise in the global home appliance markets, consumers face the inconvenience of short battery life and frequent emptying of the dust box. To solve this inconvenience, a station tower that can automatically charge the battery and empty the dust box has been developed. However, aerodynamic noise generated when the station tower sucks dust causes another inconvenience. The purpose of this study is to identify the major aerodynamic noise sources that occur when such a station tower is connected to a wireless vacuum cleaner and operate, and to develop a low-noise design based on this. First, the entire flow path of a cordless vacuum cleaner and a station tower was simulated using the unsteady compressible RANS equations. Then, the main aerodynamic noise sources were identified using the vortex sound sources. From these results, the flow region through the head throat of the cordless vacuum cleaner was identified one of the most significant aerodynamic noise sources. Based on the identified noise source mechanism, new throat design was proposed, and its validity was investigated using a high-resolution Large Eddy Simulation technique. It was found that the strength of vortex sound source of pipe flow through the new head throat was much less than the original one. Finally, the new design geometry was applied to create a prototype, and the sound pressure spectrum measured for the prototype was compared to the original, which showed that the radiated noise level of the new one was less than the original one.

Aeroelastic response of an elastically mounted 2-DOF airfoil and its gust-induced oscillations

The paper is concerned with numerical investigations on the effect of vertical wind gusts on airfoils in a parameter range relevant for Micro-Air Vehicles. Using a simplified substitute model instead of an elastic wing, a rigid but elastically mounted airfoil with two degrees of freedom (heave and pitch) is considered. The coupled problem is tackled by a partitioned fluid–structure interaction coupling scheme based on the large-eddy simulation (LES) technique and a rigid-body solver. In order to describe the effect of deterministic 1-cosine gusts of different gust lengths and gust strengths, the split velocity method (SVM) is incorporated into the simulation framework relying on the Arbitrary Lagrangian–Eulerian (ALE) formulation on temporally varying control volumes. First the flow fields and the corresponding aerodynamic forces during the direct airfoil–gust interaction are compared for a fixed and an elastically mounted airfoil. The intrinsic study on the elastic case includes nine different gust scenarios in the transitional Reynolds number regime in order to investigate the resulting flow fields and motion patterns and to answer the question whether limit-cycle oscillations (LCO) or even flutter can be induced. The results show that in seven of the studied cases, the airfoil–gust interaction leads to sustained heave and pitch oscillations of bounded amplitudes (i.e., LCO). Further investigations clarify that this can be physically attributed to the laminar separation taking place on the upper and lower surfaces of the airfoil. The two strongest gust cases, however, excite the airfoil to levels above its critical angle of attack and triggered a pitch-induced diverging flutter. An energy analysis of both characteristic scenarios (i.e., LCO and flutter) further elucidates the differences between both cases. The former case is driven by the heave motion, whereas the pitch DOF acts as an energy sink. Contrarily, in the case of flutter the pitching motion is powering the coupled system, whereas the heave motion dissipates energy.

스윙형 체크 밸브의 유체 유발 진동 저감을 위한 디스크 형상 연구

A check valve is installed in many pipe systems to allow flow only a certain direction. A swing-type check valve has been often utilized due to its lower pressure drop, reliable sealing, and a wide range of available sizes. However, repeated vibration of a disc during operation in an unsuitable velocity range leads to excessive wear of disc components. The present study provides the method of reducing flow-induced vibrational damage on a disc by attaching a pair of winglet-like structures to a disc. The attached structures are parameterized by two control parameters, the height(H) and the attached angle(θ). The vibration reduction performances for different combinations of the control parameters are investigated using computational fluid dynamics simulation with a large-eddy simulation technique.

Numerical Study on Flow and Noise Characteristics of an NACA0018 Airfoil with a Porous Trailing Edge

An airfoil with a porous trailing edge has a low noise emission; thus, using a porous medium is a good technique for further reduction of wind turbine noise. In this paper, to reduce airfoil trailing edge noise while minimizing the negative influence of a porous medium on aerodynamic performance, a new filling method is proposed such that a porous medium is only used in the suction side half of the trailing edge, which is more sensitive to the noise generation. The large eddy simulation (LES) technique for flow and the Ffowcs Williams and Hawkings (FW-H) method for acoustics are used. At a Reynolds number of 2.63 × 105 and various angles of attack, an NACA0018 airfoil profile with a porous trailing edge covering 20% of the chord is studied under two porous configurations, namely a fully porous and a suction-side porous trailing edge type. The results show that the flow direction, velocity magnitude, and their distributions along the boundary layer of the two porous airfoils are significantly modified due to the presence of the porous medium. The fluctuation of the pressure coefficient and the increase in the boundary layer thickness are significant at low angles of attack. As compared to the solid airfoil counterpart, the noise radiation from the newly proposed suction-side porous airfoil achieves a noise reduction of 4.3 dB at an angle of attack α = 0°, and a noise reduction of 4.07 dB at an angle of attack α = 2°.