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1

Guan, Lixian, and Dan Zhao. "Numerical prediction nonlinear heat-driven acoustics behaviours in standing-wave thermoacoustic engines using stress-blended Eddy simulation method." Journal of the Acoustical Society of America 153, no. 3_supplement (2023): A38. http://dx.doi.org/10.1121/10.0018072.

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The present work investigated a standing-wave heat-driven thermoacoustic engine (SWTAE) system by capturing its nonlinear thermoacoustic features with three-dimensional (3D) unsteady Reynolds-Averaged Navier-Stokes (URANS) and hybrid URANS/LES (large Eddy simulation) models such as detached-Eddy simulations (DES) and stress-blended Eddy simulation (SBES) models. The comparison studies show that the prediction of the acoustic power of SWTAE using URANS is about 21.0% lower than that using LES, while the results from SBES and DES are relatively in good agreement with LES. Comparative studies of
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2

Giri, Ajay Adhyanth, Laurence Morgan, Yan Wu, et al. "Aerodynamic model comparison for an X-shaped vertical-axis wind turbine." Wind Energy Science 9, no. 2 (2024): 453–70. https://doi.org/10.5194/wes-9-453-2024.

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This article presents a comparison study of different aerodynamic models for an X-shaped verticalaxis wind turbine and offers insight into the 3D aerodynamics of this rotor at fixed pitch offsets. The study compares six different numerical models: a double-multiple streamtube (DMS) model, a 2D actuator cylinder (2DAC) model, an inviscid free vortex wake model (from CACTUS), a free vortex wake model with turbulent vorticity (from QBlade), a blade-resolved unsteady Reynolds-averaged Navier–Stokes (URANS) model, and a lattice Boltzmann method (from PowerFLOW). All models, except URANS and P
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Giri Ajay, Adhyanth, Laurence Morgan, Yan Wu, et al. "Aerodynamic model comparison for an X-shaped vertical-axis wind turbine." Wind Energy Science 9, no. 2 (2024): 453–70. http://dx.doi.org/10.5194/wes-9-453-2024.

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Abstract. This article presents a comparison study of different aerodynamic models for an X-shaped vertical-axis wind turbine and offers insight into the 3D aerodynamics of this rotor at fixed pitch offsets. The study compares six different numerical models: a double-multiple streamtube (DMS) model, a 2D actuator cylinder (2DAC) model, an inviscid free vortex wake model (from CACTUS), a free vortex wake model with turbulent vorticity (from QBlade), a blade-resolved unsteady Reynolds-averaged Navier–Stokes (URANS) model, and a lattice Boltzmann method (from PowerFLOW). All models, except URANS
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4

Baungaard, M., M. P. Van Der Laan, M. Kelly, and E. L. Hodgson. "Simulation of a conventionally neutral boundary layer with two-equation URANS." Journal of Physics: Conference Series 2767, no. 5 (2024): 052013. http://dx.doi.org/10.1088/1742-6596/2767/5/052013.

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Abstract Simulating conventionally neutral boundary layers (CNBLs) with the unsteady Reynolds-Averaged Navier-Stokes (URANS) technique is investigated in this paper using a modified two-equation linear eddy viscosity turbulence model. For CNBLs over a flat and uniform surface, as typically used as the inflow to wind farm simulations, the governing equations of URANS can be solved with a one-dimensional solver, which makes the simulation of a typical CNBL five to six orders of magnitude faster than with large-eddy simulation (LES) approaches. However, URANS on the other hand requires more model
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5

Klimczyk, Witold, and Adam Sieradzki. "Airofil Tonal Noise Prediction Using Urans." Transactions on Aerospace Research 2023, no. 4 (2023): 1–17. http://dx.doi.org/10.2478/tar-2023-0019.

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Abstract To examine the feasibility of the laminar boundary layer (LBL), vortex shedding (VS) tonal noise modelling using unsteady Reynolds-averaged Navier–Stokes (URANS) was investigated for the non-symmetric S834 airfoil. A transition SST turbulence model was used to model the laminar-turbulent transition and its vital influence on the laminar bubble and hydrodynamic instabilities generation. The influence of turbulence on the unsteady vortex patterns was investigated. Hence, the hybrid aeroacoustic analysis with Lighthill analogy was conducted to obtain the acoustic pressure field. The appr
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6

Saha, A. K., and Sumanta Acharya. "Flow and Heat Transfer in an Internally Ribbed Duct With Rotation: An Assessment of Large Eddy Simulations and Unsteady Reynolds-Averaged Navier-Stokes Simulations." Journal of Turbomachinery 127, no. 2 (2004): 306–20. http://dx.doi.org/10.1115/1.1861917.

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Large eddy simulations (LES) and unsteady Reynolds averaged Navier-Stokes (URANS) simulations have been performed for flow and heat transfer in a rotating ribbed duct. The ribs are oriented normal to the flow and arranged in a staggered configuration on the leading and trailing surfaces. The LES results are based on a higher-order accurate finite difference scheme with a dynamic Smagorinsky model for the subgrid stresses. The URANS procedure utilizes a two equation k-ε model for the turbulent stresses. Both Coriolis and centrifugal buoyancy effects are included in the simulations. The URANS co
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7

Wu, Huajie, and Shanwen Zhang. "Flow field analysis of Ahmed model based on URANS." Journal of Physics: Conference Series 1983, no. 1 (2021): 012021. http://dx.doi.org/10.1088/1742-6596/1983/1/012021.

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8

Kamalov, Bagdaulet, Sagidolla Batay, Dinmukhamed Zhangaskhanov, Yong Zhao, and Eddie Yin Kwee Ng. "Arbitrary Hybrid Turbulence Modeling Approach for High-Fidelity NREL Phase VI Wind Turbine CFD Simulation." Fluids 7, no. 7 (2022): 236. http://dx.doi.org/10.3390/fluids7070236.

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Today, growth in renewable energy is increasing, and wind energy is one of the key renewable energy sources which is helping to reduce carbon emissions and build a more sustainable world. Developed countries and worldwide organizations are investing in technology and industrial application development. However, extensive experiments using wind turbines are expensive, and numerical simulations are a cheaper alternative for advanced analysis of wind turbines. The aerodynamic properties of wind turbines can be analyzed and optimized using CFD tools. Currently, there is a general lack of available
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9

Gavrilov, Andrey, and Yaroslav Ignatenko. "Numerical Simulation of Taylor—Couette—Poiseuille Flow at Re = 10,000." Fluids 8, no. 10 (2023): 280. http://dx.doi.org/10.3390/fluids8100280.

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A fully developed turbulent flow in a concentric annulus, Re =10,000, ri/ro=0.5, with an inner rotating cylinder in the velocity range N=Uω/Ub=0÷4, is studied via a large-eddy simulation. Also, for comparison, simulations by steady-state, unstatiounary RANS k-ω SST (URANS), and Elliptic Blending Model (EBM) were made. The main focus of this study is on the effect of high rotation on the mean flow, turbulence statistics, and vortex structure. Distribution of the tangential velocity and the Reynolds stress tensor change their behaviour at N>0.5∼1. With rotation increases, the production of ta
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10

Ehrle, Maximilian, Andreas Waldmann, Thorsten Lutz, and Ewald Krämer. "Simulation of transonic buffet with an automated zonal DES approach." CEAS Aeronautical Journal 11, no. 4 (2020): 1025–36. http://dx.doi.org/10.1007/s13272-020-00466-7.

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Abstract A study of transonic buffet on the NASA Common Research Model at flight Reynolds numbers is presented. The ability of two different hybrid RANS/LES models as well as the URANS approach for resolving three-dimensional buffet motion was evaluated by means of spectral analysis. Automated Zonal DES and URANS simulations show similar results in terms of buffet frequency and spanwise propagation of buffet cells, whereas the Delayed Detached Eddy Simulation results indicate a strong interaction between flow separation and shock motion. The extracted characteristic frequencies which are assoc
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11

Hakim, Samhuddin. "Analisa numerik karakteristik aliran di sekitar struktur bentuk menyilang menggunakan model uRANS." Dinamika : Jurnal Ilmiah Teknik Mesin 13, no. 1 (2021): 69. http://dx.doi.org/10.33772/djitm.v13i1.21645.

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Karakteristik aerostatik penampang struktur berbentuk menyilang diteliti secara numerik menggunakan model unsteady Reynold Average Navier-Stokes (uRANS) dua dimensi dengan model turbulensi SST k-w. Sudut aliran masuk yang berbeda digunakan untuk menyelidiki fitur aliran di sekitar struktur tersebut. Hasil penelitian menunjukkan bahwa tekanan dasar maksimum dicapai pada sudut serang (a) = 30 derajat di mana vortisitas negatif menggulung di belakang struktur relatif jauh dari benda. Gaya aerodinamika model dengan a= 30 derajat adalah kesepakatan yang masuk akal untuk hasil eksperimen. Frekuensi
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12

Purohit, Shantanu, Ijaz Fazil Syed Ahmed Kabir, and E. Y. K. Ng. "On the Accuracy of uRANS and LES-Based CFD Modeling Approaches for Rotor and Wake Aerodynamics of the (New) MEXICO Wind Turbine Rotor Phase-III." Energies 14, no. 16 (2021): 5198. http://dx.doi.org/10.3390/en14165198.

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This work presents a comparison study of the CFD modeling with two different turbulence modeling approaches viz. unsteady RANS and LES, on a full-scale model of the (New) MEXICO rotor wind turbine. The main emphasis of the paper is on the rotor and wake aerodynamics. Simulations are carried out for the three wind speeds considered in the MEXICO experiment (10, 15, and 24 ms−1). The results of uRANS and LES are compared against the (New) MEXICO experimental measurements of pressure distributions, axial, radial, and azimuth traverse of three velocity components. The near wake characteristics and
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13

Decaix, Jean, Vlad Hasmatuchi, Maximilian Titzschkau, and Cécile Münch-Alligné. "CFD Investigation of a High Head Francis Turbine at Speed No-Load Using Advanced URANS Models." Applied Sciences 8, no. 12 (2018): 2505. http://dx.doi.org/10.3390/app8122505.

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Due to the integration of new renewable energies, the electrical grid undergoes instabilities. Hydroelectric power plants are key players for grid control thanks to pumped storage power plants. However, this objective requires extending the operating range of the machines and increasing the number of start-up, stand-by, and shut-down procedures, which reduces the lifespan of the machines. CFD based on standard URANS turbulence modeling is currently able to predict accurately the performances of the hydraulic turbines for operating points close to the Best Efficiency Point (BEP). However, far f
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14

Krastev, Vesselin Krassimirov, Giovanni Di Ilio, Clara Iacovano, Alessandro d’Adamo, and Stefano Fontanesi. "Standard and consistent Detached-Eddy Simulation for turbulent engine flow modeling: an application to the TCC-III engine." E3S Web of Conferences 197 (2020): 06021. http://dx.doi.org/10.1051/e3sconf/202019706021.

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Multidimensional modeling of Cycle-to-Cycle Variability (CCV) has become a crucial support for the development and optimization of modern direct-injection turbocharged engines. In that sense, the only viable modeling options is represented by scale-resolving approaches such as Large Eddy Simulation (LES) or hybrid URANS/LES methods. Among other hybrid approaches, Detached-Eddy Simulation (DES) has the longest development story and is therefore commonly regarded as the most reliable choice for engineering-grade simulation. As such, in the last decade DESbased methods have found their way throug
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15

Viswanathan, Aroon K., and Danesh K. Tafti. "A Comparative Study of DES and URANS for Flow Prediction in a Two-Pass Internal Cooling Duct." Journal of Fluids Engineering 128, no. 6 (2006): 1336–45. http://dx.doi.org/10.1115/1.2353279.

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The capabilities of the detached eddy simulation (DES) and the unsteady Reynolds averaged Navier-Stokes (URANS) versions of the 1988 k-ω model in predicting the turbulent flow field in a two-pass internal cooling duct with normal ribs is presented. The flow is dominated by the separation and reattachment of shear layers; unsteady vorticity induced secondary flows and strong streamline curvature. The techniques are evaluated in predicting the developing flow at the entrance to the duct and downstream of the 180deg bend, fully developed regime in the first pass, and in the 180deg bend. Results o
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16

Turrini, Marco, Kisorthman Vimalakanthan, and Edwin Bot. "Advancements in Wind Turbine Wake Modelling using 3D scanning LiDAR measurements." Journal of Physics: Conference Series 3016, no. 1 (2025): 012005. https://doi.org/10.1088/1742-6596/3016/1/012005.

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Abstract This study investigates the capability of numerical models to estimate wind turbine wake characteristics under varying atmospheric stability conditions using three-dimensional wind data obtained from a scanning LiDAR. The LiDAR was set to measure the wake of a 3.8 MW test turbine up to 5 rotor diameters downstream from the hub, for a period of four months, capturing both vertical and horizontal wake profiles. These measurements were compared against results from the parabolized Navier-Stokes (PNS) solver FarmFlow (FF) and Unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations. T
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Benim, Ali Cemal, Sohail Iqbal, Franz Joos, and Alexander Wiedermann. "Numerical Analysis of Turbulent Combustion in a Model Swirl Gas Turbine Combustor." Journal of Combustion 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/2572035.

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Turbulent reacting flows in a generic swirl gas turbine combustor are investigated numerically. Turbulence is modelled by a URANS formulation in combination with the SST turbulence model, as the basic modelling approach. For comparison, URANS is applied also in combination with the RSM turbulence model to one of the investigated cases. For this case, LES is also used for turbulence modelling. For modelling turbulence-chemistry interaction, a laminar flamelet model is used, which is based on the mixture fraction and the reaction progress variable. This model is implemented in the open source CF
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18

Avila, Matias, O. Lehmkuhl, J. Navarro, et al. "Microscale simulations of extreme events in complex terrain driven by mesoscalar budget components." Journal of Physics: Conference Series 2265, no. 2 (2022): 022021. http://dx.doi.org/10.1088/1742-6596/2265/2/022021.

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Abstract In this work, we apply a downscaling strategy to analyze extreme weather events that may impact wind farm operation. The coupling applies mesoscale momentum budget components (tendencies) from the WRF model as forcing terms to the governing microscale equations. Our study focuses on flow over complex terrain during specific days to reproduce extreme weather events that produced wind turbine damage. The interaction of the meso- and micro-scale features are relevant in the simulation of extreme conditions. The simulation results are compared with observations from nacelle anemometers of
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el Moctar, Ould, Udo Lantermann, Vladimir Shigunov, and Thomas E. Schellin. "Experimental and numerical investigations of effects of ship superstructures on wind-induced loads for benchmarking." Physics of Fluids 35, no. 4 (2023): 045124. http://dx.doi.org/10.1063/5.0146778.

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For a representative large modern containership, the effects of a deck container arrangement on the wind-induced loads were systematically investigated using physical model tests and numerical computations. Numerical simulations based on various turbulence models were performed to validate our predictions against comparative wind tunnel measurements. Not only standard two-equation turbulence models of the unsteady Reynolds-Averaged Navier–Stokes (URANS) equations solver but also the improved delayed detached eddy simulation (IDDES) and large eddy simulation (LES) turbulence models were used to
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20

Yang, Xianglong, and Lei Yang. "An Elliptic Blending Turbulence Model-Based Scale-Adaptive Simulation Model Applied to Fluid Flows Separated from Curved Surfaces." Applied Sciences 12, no. 4 (2022): 2058. http://dx.doi.org/10.3390/app12042058.

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On the basis of a previously developed elliptic blending turbulence model (SST–k–ω–φ–α model), a scale-adaptive simulation (SAS) model is developed by following Menter and Egorov’s SAS concept. An SAS source term, which is related to the ratio of the modeled turbulence scale to the von Kármán length scale, is introduced into the corresponding length-scale determining equation. The major motivation of this study is that the conventional unsteady Reynolds-averaged Navier–Stokes (URANS) models provide only large-scale unsteadiness. The introduction of the SAS term allows the proposed SAS model to
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Zhang, Xin, Heng Zhang, and Jie Li. "Numerical Investigation of Stall Characteristics of Common Research Model Configuration Based on Zonal Detached Eddy Simulation Method." Aerospace 10, no. 9 (2023): 817. http://dx.doi.org/10.3390/aerospace10090817.

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A zonal detached eddy simulation (ZDES) method, based on the two-equation k-ω SST turbulence model, was employed to predict stall characteristics and capture small-scale vortex structures in the wake region of the main wing under the post-stall condition of the Common Research Model (CRM) configuration. Additionally, the unsteady Reynolds-averaged Navier–Stokes (URANS) method was utilized for performance comparison in resolving small-scale vortices with ZDES. The results revealed a pronounced lateral flow on the wing, induced by the low-pressure region of the inner wing at post-stall angles of
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Stalewski, Wieńczysław, and Katarzyna Surmacz. "Helicopter Flight Simulation based on URANS Solver and Virtual Blade Model." Journal of KONES 26, no. 3 (2019): 211–17. http://dx.doi.org/10.2478/kones-2019-0075.

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Abstract The methodology of simulation of a rotorcraft flight has been developed and applied to simulate several stages of flight of light helicopter. The methodology is based on coupling of several computational models of Computational Fluid Dynamics, Flight Dynamic. The essence of the methodology consists in calculation of aerodynamic forces acting on the flying rotorcraft by solving during the simulation the Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations. In this approach, the rotorcraft is flying inside the computational 3D mesh modelling the space filled with the air. The flig
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INOUE, Rintaroh, Ichirou KIMURA, and Yasuyuki SHIMIZU. "COMPUTATIONS ON MEANDERING COMPOUND OPEN CHANNEL FLOWS USING 3D URANS MODEL." Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering) 67, no. 4 (2011): I_1015—I_1020. http://dx.doi.org/10.2208/jscejhe.67.i_1015.

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Richardson, G. A., W. N. Dawes, and A. M. Savill. "An unsteady, moving mesh CFD simulation for Harrier hot-gas ingestion control analysis." Aeronautical Journal 111, no. 1117 (2007): 133–44. http://dx.doi.org/10.1017/s0001924000004395.

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Hot gas ingestion (HGI) can be a problematic feature of short take-off vertical landing (STOVL) aircraft during the descent phase of landing, or while on the ground. The hot exhaust gases from the downwards pointing nozzles can be re-ingested into the engine intakes, causing power degradation or reduced engine surge margin. The flow-fields that characterise this phenomenon are complex, with supersonic impinging jets and cross-flows creating large ground vortices and fountain up-wash flows. A flow solver has been developed to include a suitable linear mesh deformation technique for the descendi
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25

Murugu, Sakthi Prakash, A. R. Srikrishnan, Bharath Kumar Krishnaraj., Anguraj Jayaraj, Akram Mohammad, and Ratna Kishore Velamati. "Acoustic Modeling of Compressible Jet from Chevron Nozzle: A Comparison of URANS, LES and DES Models." Symmetry 14, no. 10 (2022): 1975. http://dx.doi.org/10.3390/sym14101975.

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Chevron nozzles, which are characterized by the serrations at the nozzle exit, are widely used for suppressing jet noise in aircraft engines. The noise suppression is accomplished by the enhanced mixing of the exhaust streams, which, in turn, is a result of the streamwise vorticity induced by the serrations. The present study focuses on the numerical modeling of the acoustic field in a compressible jet issuing from a chevron nozzle at a Mach number of 0.8. The study evaluates the effectiveness of turbulence modeling approaches of Large Eddy Simulation and Detached Eddy Simulation methods and c
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Zhang, Yang, Laiping Zhang, Xin He, Xiaogang Deng, and Haisheng Sun. "Detached Eddy Simulation of Complex Separation Flows Over a Modern Fighter Model at High Angle of Attack." Communications in Computational Physics 22, no. 5 (2017): 1309–32. http://dx.doi.org/10.4208/cicp.oa-2016-0132.

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AbstractThis paper presents the simulation of complex separation flows over a modern fighter model at high angle of attack by using an unstructured/hybrid grid based Detached Eddy Simulation (DES) solver with an adaptive dissipation second-order hybrid scheme. Simulation results, including the complex vortex structures, as well as vortex breakdown phenomenon and the overall aerodynamic performance, are analyzed and compared with experimental data and unsteady Reynolds-Averaged Navier-Stokes (URANS) results, which indicates that with the DES solver, clearer vortical flow structures are captured
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Krastev, Vesselin Krassimirov, Alessandro d’Adamo, Fabio Berni, and Stefano Fontanesi. "Validation of a zonal hybrid URANS/LES turbulence modeling method for multi-cycle engine flow simulation." International Journal of Engine Research 21, no. 4 (2019): 632–48. http://dx.doi.org/10.1177/1468087419851905.

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A zonal hybridization of the RNG [Formula: see text]-[Formula: see text] URANS model is proposed for the simulation of turbulent flows in internal combustion engines. The hybrid formulation is able to act as URANS, DES or LES in different zones of the computational domain, which are explicitly set by the user. The resulting model has been implemented in a commercial computational fluid dynamics code and the LES branch of the modified RNG [Formula: see text]-[Formula: see text] closure has been initially calibrated on a standard homogeneous turbulence box case. Subsequently, the full zonal form
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Martineau Rousseau, Philippe, Azzeddine Soulaïmani, and Michel Sabourin. "Efficiency Assessment for Rehabilitated Francis Turbines Using URANS Simulations." Water 13, no. 14 (2021): 1883. http://dx.doi.org/10.3390/w13141883.

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Due to the large number of aging hydraulic turbines in North America, rehabilitation is a growing market as these turbines have low efficiency compared to modern ones. Computational Fluid Dynamics identifies components with poor hydraulic performance. The models often used in industry are based on individually analyzing the sub-components of a turbine instead of full turbine simulations due to computational and time limitations. An industrial case has shown that such analyses may lead to underestimating the efficiency increases by modifying the stay vane. The unsteady full turbine simulation p
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Chang, Kyoungsik, George Constantinescu, and Seung-O. Park. "Assessment of Predictive Capabilities of Detached Eddy Simulation to Simulate Flow and Mass Transport Past Open Cavities." Journal of Fluids Engineering 129, no. 11 (2007): 1372–83. http://dx.doi.org/10.1115/1.2786529.

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The three-dimensional (3D) incompressible flow past an open cavity in a channel is predicted using the Spalart–Almaras (SA) and the shear-stress-transport model (SST) based versions of detached eddy simulation (DES). The flow upstream of the cavity is fully turbulent. In the baseline case the length to depth (L∕D) ratio of the cavity is 2 and the Reynolds number ReD=3360. Unsteady RANS (URANS) is performed to better estimate the performance of DES using the same code and meshes employed in DES. The capabilities of DES and URANS to predict the mean flow, velocity spectra, Reynolds stresses, and
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Kratzsch, Christoph, Amjad Asad, and Rüdiger Schwarze. "CFD of the MHD Mold Flow by Means of Hybrid LES/RANS Turbulence Modeling." Journal for Manufacturing Science and Production 15, no. 1 (2015): 49–57. http://dx.doi.org/10.1515/jmsp-2014-0046.

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AbstractIn the last decades, electromagnetic braking (EMBr) systems become a powerful tool to dampen possible jet oscillations in the continuous casting mold. Further studies showed that if a EMBr is not positioned correctly, it can induce flow oscillations. Hence, the design of these braking systems can be promoted by adequate CFD simulations. In most cases, unsteady RANS simulations (URANS) are sufficient to resolve low-frequency, large-scale oscillations of these MHD flows. Alternatively, Large Eddy Simulations (LES) may also resolve important details of the turbulence. However, since they
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Ja’fari, Mohammad, Artur J. Jaworski, and Aldo Rona. "Numerical study of flow separation control over a circular hump using synthetic jet actuators." AIP Advances 12, no. 9 (2022): 095205. http://dx.doi.org/10.1063/5.0099926.

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This study deals with the wall resolved Unsteady Reynolds-Averaged Navier–Stokes (URANS) simulation of boundary layer flow separation over a circular hump model and its active control. An array of Synthetic Jet Actuators (SJAs) is implemented in the hump model to introduce a train of vortex rings into the boundary layer to control flow separation. The OpenFOAM solver is used to numerically simulate and analyze the fluid flow using the k– ω shear stress transport model. Hot wire anemometry and particle image velocimetry measurements are carried out to evaluate the accuracy of the URANS techniqu
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Zahn, Rebecca, and Christian Breitsamter. "Neuro-Fuzzy Network-Based Reduced-Order Modeling of Transonic Aileron Buzz." Aerospace 7, no. 11 (2020): 162. http://dx.doi.org/10.3390/aerospace7110162.

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In the present work, a reduced-order modeling (ROM) framework based on a recurrent neuro-fuzzy model (NFM) that is serial connected with a multilayer perceptron (MLP) neural network is applied for the computation of transonic aileron buzz. The training data set for the specified ROM is obtained by performing forced-motion unsteady Reynolds-averaged Navier Stokes (URANS) simulations. Further, a Monte Carlo-based training procedure is applied in order to estimate statistical errors. In order to demonstrate the method’s fidelity, a two-dimensional aeroelastic model based on the NACA651213 airfoil
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Oz, Furkan, and Kursat Kara. "Jet Oscillation Frequency Characterization of a Sweeping Jet Actuator." Fluids 5, no. 2 (2020): 72. http://dx.doi.org/10.3390/fluids5020072.

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The time-resolved flow field of a spatially oscillating jet emitted by a sweeping jet (SWJ) actuator is investigated numerically using three-dimensional Reynolds-averaged Navier–Stokes (3D-URANS) equations. Numerical simulations are performed for a range of mass flow rates providing flow conditions varying from incompressible to subsonic compressible flows. After a detailed mesh study, the computational domain is represented using two million hexagonal control volumes. The jet oscillation frequency is predicted by analyzing velocity time histories at the actuator exit, and a linear relationshi
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Girimaji, Sharath S., Eunhwan Jeong, and Ravi Srinivasan. "Partially Averaged Navier-Stokes Method for Turbulence: Fixed Point Analysis and Comparison With Unsteady Partially Averaged Navier-Stokes." Journal of Applied Mechanics 73, no. 3 (2005): 422–29. http://dx.doi.org/10.1115/1.2173677.

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Hybrid/bridging models that combine the advantages of Reynolds averaged Navier Stokes (RANS) method and large-eddy simulations are being increasingly used for simulating turbulent flows with large-scale unsteadiness. The objective is to obtain accurate estimates of important large-scale fluctuations at a reasonable cost. In order to be effective, these bridging methods must posses the correct “energetics”: that is, the right balance between production (P) and dissipation (ε). If the model production-to-dissipation ratio (P∕ε) is inconsistent with turbulence physics at that cutoff, the computat
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García, J., J. Muñoz-Paniagua, L. Xu та E. Baglietto. "A second-generation URANS model (STRUCT-ε) applied to simplified freight trains". Journal of Wind Engineering and Industrial Aerodynamics 205 (жовтень 2020): 104327. http://dx.doi.org/10.1016/j.jweia.2020.104327.

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36

Bazdidi-Tehrani, Farzad, and Mehdi Jahromi. "ANALYSIS OF SYNTHETIC JET FLOW FIELD: APPLICATION OF URANS APPROACH." Transactions of the Canadian Society for Mechanical Engineering 35, no. 3 (2011): 337–53. http://dx.doi.org/10.1139/tcsme-2011-0019.

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The present paper reports the time dependent simulation of a turbulent plane synthetic jet using an unsteady Reynolds averaged Navier-Stokes approach on the basis of the first and second moment closure turbulence models. All the applied turbulence models can capture a global feature of the long time averaged flow field quite well. However, the standard k – ε model yields a disappointing prediction of the turbulence field with inaccurately high levels of turbulence kinetic energy and normal Reynolds stress distributions. The second moment closure model with quadratic nonlinear pressure strain a
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37

Shi, Wenbo, Heng Zhang, and Yuanxiang Li. "A Zonal Detached Eddy Simulation of the Trailing Edge Stall Process of a LS0417 Airfoil." Aerospace 11, no. 9 (2024): 731. http://dx.doi.org/10.3390/aerospace11090731.

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A Zonal Detached Eddy Simulation (ZDES) based on the SST turbulence model is implemented to the numerical investigation of the trailing edge stall of a LS-0417 airfoil, which includes multiple DES modes for different classifications of flow separation and adopts the subgrid scale definition of Δω. The entire stall process under a series of AOA is simulated according to the experiment condition. The performance of URANS and ZDES in the prediction of the stall flow field are compared. The results reveal that the stall point obtained through ZDES is consistent with the experiment; the deviation o
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38

Ma, Lun, Pierre-Luc Delafin, Panagiotis Tsoutsanis, Antonis Antoniadis, and Takafumi Nishino. "Blade-Resolved CFD Simulations of a Periodic Array of NREL 5 MW Rotors with and without Towers." Wind 2, no. 1 (2022): 51–67. http://dx.doi.org/10.3390/wind2010004.

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A fully resolved (FR) NREL 5 MW turbine model is employed in two unsteady Reynolds-averaged Navier–Stokes (URANS) simulations (one with and one without the turbine tower) of a periodic atmospheric boundary layer (ABL) to study the performance of an infinitely large wind farm. The results show that the power reduction due to the tower drag is about 5% under the assumption that the driving force of the ABL is unchanged. Two additional simulations using an actuator disc (AD) model are also conducted. The AD and FR results show nearly identical tower-induced reductions of the wind speed above the
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39

Gopalakrishnan Meena, Muralikrishnan, Demetri Liousas, Andrew D. Simin, et al. "Machine-learned closure of URANS for stably stratified turbulence: connecting physical timescales & data hyperparameters of deep time-series models." Machine Learning: Science and Technology 5, no. 4 (2024): 045063. https://doi.org/10.1088/2632-2153/ad9704.

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Abstract Stably stratified turbulence (SST), a model that is representative of the turbulence found in the oceans and atmosphere, is strongly affected by fine balances between forces and becomes more anisotropic in time for decaying scenarios. Moreover, there is a limited understanding of the physical phenomena described by some of the terms in the Unsteady Reynolds-Averaged Navier–Stokes (URANS) equations—used to numerically simulate approximate solutions for such turbulent flows. Rather than attempting to model each term in URANS separately, it is attractive to explore the capability of mach
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Meng, Qingjie, and Decheng Wan. "URANS Studies of Effect of Eccentricity on Ship–Lock Interactions." International Journal of Computational Methods 13, no. 04 (2016): 1641012. http://dx.doi.org/10.1142/s0219876216410127.

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The unsteady viscous flow around a 12000TEU ship model entering the Third Set of Panama Locks with different eccentricity is simulated by solving the unsteady Reynolds averaged Navier–Stokes (RANS) equations in combination with the [Formula: see text]SST turbulence model. Overset grid technology is utilized to maintain grid orthogonality and the effects of the free surface are taken into account. The hydrodynamic forces, vertical displacement as well as surface pressure distribution are predicted and analyzed. First, a benchmark test case is designed to validate the capability of the present m
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Zbavitel, Jan, and Simona Fialová. "A numerical study of hemodynamic effects on the bileaflet mechanical heart valve." EPJ Web of Conferences 213 (2019): 02103. http://dx.doi.org/10.1051/epjconf/201921302103.

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The work is focused on calculating hemodynamically negative effects of a flow through bileaflet mechanical heart valves (BMHV). Open-source FOAM-extend and cfMesh libraries were used for numerical simulation, the leaflet movement was solved as a fluid-structure interaction. A real model of the Sorin Bicarbon heart valve was employed as the default geometry for the following shape improvement. The unsteady boundary conditions correspond to physiological data of a cardiac cycle. It is shown how the modification of the shape of the original valve geometry positively affected the size of backflow
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42

Holman, Jiří. "Unsteady Flow past a Circular Cylinder Using Advanced Turbulence Models." Applied Mechanics and Materials 821 (January 2016): 23–30. http://dx.doi.org/10.4028/www.scientific.net/amm.821.23.

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This work deals with the numerical simulation of unsteady compressible turbulent flow past a circular cylinder. Turbulent flow is modeled by two different methods. The first method is based on the system of URANS equations closed by the two equation TNT model or modified EARSM model. Second method is based on the X-LES model, which is a hybrid RANS-LES method. Numerical solution is obtained by the finite volume method. Presented results are for the sub-critical turbulent flow characterized by Re=3900.
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Chen, X., L. W. Liu, Z. G. Zhang, X. Z. Wang, and D. K. Feng. "URANS assessment of ship extreme roll event in irregular stern quartering sea." IOP Conference Series: Materials Science and Engineering 1288, no. 1 (2023): 012004. http://dx.doi.org/10.1088/1757-899x/1288/1/012004.

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Abstract In this study, the extreme roll events of a free-running ONR Tumblehome model in stern quartering seas are predicted by an unsteady Reynolds-averaged Navier–Stokes (URANS) solver coupled with a dynamic overset grid approach. The validation study is first performed for the prediction of ship extreme roll amplitude in regular waves, indicating satisfactory agreement with an average difference of less than 3% between the simulation and experimental results. The URANS approach is then applied to the assessment of the extreme roll events as the ship is sailing in irregular seas. The ship i
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Sereez, Mohamed, Nikolay Abramov, and Mikhail Goman. "CFD Simulations and Phenomenological Modelling of Aerodynamic Stall Hysteresis of NACA 0018 Wing." Aerospace 11, no. 5 (2024): 354. http://dx.doi.org/10.3390/aerospace11050354.

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Computational simulations of three-dimensional flow around a NACA 0018 wing with an aspect ratio of AR=5 were carried out by using the Unsteady Reynolds-Averaged Navier–Stokes (URANS) equations with the Shear-Stress Transport turbulence model closure. Simulations were performed to capture aerodynamic stall hysteresis by using the developed pseudo-transient continuation (PTC) method based on a dual-time step approach in CFD OpenFOAM code. The flow was characterized by incompressible Mach number M=0.12 and moderate Reynolds number Re=0.67×106. The results obtained indicate the presence of notice
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Cornelius, Jason, Sven Schmitz, Jose Palacios, Bernadine Juliano, and Richard Heisler. "Rotor Performance Predictions for Urban Air Mobility: Single vs. Coaxial Rigid Rotors." Aerospace 11, no. 3 (2024): 244. http://dx.doi.org/10.3390/aerospace11030244.

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This work details the development and validation of a methodology for high-resolution rotor models used in hybrid Blade Element Momentum Theory Unsteady Reynolds Averaged Navier–Stokes (BEMT-URANS) CFD. The methodology is shown to accurately predict single and coaxial rotor performance in a fraction of the time required by conventional CFD methods. The methodology has three key features: (1) a high-resolution BEMT rotor model enabling large reductions in grid size, (2) a discretized set of momentum sources to interface between the BEMT rotor model and the structured URANS flow solver, and (3)
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46

Rui, Xiaocheng, Limin Lin, Junkui Wang, et al. "Experimental and Comparative RANS/URANS Investigations on the Effect of Radius of Volute Tongue on the Aerodynamics and Aeroacoustics of a Sirocco Fan." Processes 8, no. 11 (2020): 1442. http://dx.doi.org/10.3390/pr8111442.

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The geometry of volute tongue is crucial in the design of Sirocco fans. The size of the volute tongue determines its relative position and distance from the impeller which affects the local flow characteristics and thus the aerodynamic and aeroacoustic performances of the fan. In this work, we performed experimental and numerical investigations on the effect of volute tongue radius on the aerodynamic and aeroacoustic characteristics of a Sirocco fan. The internal flow characteristics are analyzed and discussed in terms of the spatial distribution and temporal variation of pressure and streamli
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47

Escartí-Guillem, Mara S., Luis M. García-Raffi, and Sergio Hoyas. "URANS Analysis of a Launch Vehicle Aero-Acoustic Environment." Applied Sciences 12, no. 7 (2022): 3356. http://dx.doi.org/10.3390/app12073356.

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Predicting and mitigating acoustic levels become critical because of the harsh acoustic environment during space vehicle lift-off. This paper aimed to study the aero-acoustic environment during a rocket lift-off. The sound propagation within a launch event was studied using dedicated computational fluid dynamics (CFD). The resolution of all the phenomena that occur is unfeasible. We discuss the turbulence simplification and propose a feasible simulation through an unsteady Reynolds-averaged Navier–Stokes (URANS) model. The results were validated with experimental data showing a good correlatio
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48

Shahi, Mina, Jim B. W. Kok, J. C. Roman Casado, and Artur K. Pozarlik. "Assessment of thermoacoustic instabilities in a partially premixed model combustor using URANS approach." Applied Thermal Engineering 71, no. 1 (2014): 276–90. http://dx.doi.org/10.1016/j.applthermaleng.2014.06.068.

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49

Corrêa, Rafaela Gomide, João Rodrigo Andrade, and Francisco José de Souza. "Improving Separation Prediction of Cyclone Separators with a Hybrid URANS-LES Turbulence Model." Powders 2, no. 3 (2023): 607–23. http://dx.doi.org/10.3390/powders2030038.

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The CFD simulation of cyclone separators has remarkably evolved over the past decades. Nowadays, computational models are essential for designing, analyzing, and optimizing these devices. Due to the intrinsic anisotropy of the flow inside these separators, the Reynolds stress model (RSM) has been mostly employed. However, RSM models fail to solve most time and space scales, including those relevant to particle behavior. Consequently, the prediction of the grade collection efficiency may be hindered, particularly for low-Stokes-number particles. For example, the precessing vortex core phenomeno
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50

Balashov, Vladislav Aleksandrovich, Vitaly Evgenyevich Borisov, and Yana Vladislavovna Khankhasaeva. "An implicit scheme based on the LU-SGS method for URANS equations with SST turbulence model." Keldysh Institute Preprints, no. 31 (2018): 1–20. http://dx.doi.org/10.20948/prepr-2018-31.

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