Assessment of Turbulence Models over a Curved Hill Flow with Passive Scalar Transport

Paeres, David; Lagares, Christian; Araya, Guillermo

doi:10.3390/en15166013

Cited by 4 publications

(2 citation statements)

References 35 publications

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“…These equations require a model or closure to compute the Reynolds stresses, which arises from the convective terms of the NS equations after applying the time averaging process. Unfortunately, the RANS approach exhibits a deficient performance in massively separated flows or flows with inherently unsteady behavior [3] and in highly accelerated flows [4]. Recently, significant attention has been paid to relatively low-cost, scale-resolving, time-dependent computations of complex flows for industrial applications, e.g.…”

Section: Introductionmentioning

confidence: 99%

Unsteady Subsonic/Supersonic Flow Simulations in 3D Unstructured Grids over an Acoustic Cavity

Araya

2024

Preprint

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In this study, the unsteady Reynolds-averaged Navier-Stokes (URANS) equations are employed in conjunction with the Menter Shear Stress Transport (SST)-Scale-Adaptive Simulation (SAS) turbulence model in compressible flow, unstructured mesh and complex geometry. Whereas, other scale-resolving approaches in space and time, such as Direct Numerical Simulation (DNS) and Large-Eddy Simulation (LES), supply more comprehensive information about the turbulent energy spectra of the fluctuating component of the flow; however, previously mentioned avenues imply computationally intensive situations, usually performed over structured meshes and relatively simply geometries. In contrast, the SAS approach is designed according to “physically” prescribed length scales of the flow. More precisely, it operates by locally comparing the length scale of the modelled turbulence to the von Karman length scale (which is prescribed according to local fluid velocity derivatives and depends on the grid point distribution in the computational domain). This length scale ratio allows the flow to dynamically adjust the local eddy viscosity in order to better capture the large scale motions (LSM) in unsteady regions of URANS simulations. While SAS may be constrained to model only low flow frequencies or waivenumbers (i.e., LSM), its versatility and computational low-cost make it attractive to obtain a quick first insight of the flow physics; particularly, in those situations dominated by strong flow unsteadiness. The selected numerical application is the well-known M219 three-dimensional rectangular acoustic cavity from the literature at two different freestream Mach numbers, M∞ (0.85 and 1.35) and a length-to-depth ratio of 5:1. Thus, we consider the “deep configuration" in experiments by Henshaw. The SST-SAS model has demonstrated a satisfactory compromise between simplicity, accuracy and flow physics description.

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Section: Introductionmentioning

confidence: 99%

Unsteady Subsonic/Supersonic Flow Simulations in 3D Unstructured Grids over an Acoustic Cavity

Araya

2024

Preprint

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show abstract

“…These equations demand a closure to compute the Reynolds stresses arising from the convective terms of the NS equations after applying the time-averaging process. Unfortunately, the RANS approach exhibits a deficient performance in massively separated flows or flows with inherently unsteady behavior [3] and in highly accelerated flows [4]. Recently, significant attention has been paid to relatively low-cost, scale-resolving, time-dependent computations of complex flows for industrial applications, e.g., geometries with moving parts, wing flutter, noise prediction, etc.…”

Section: Introductionmentioning

confidence: 99%

Unsteady Subsonic/Supersonic Flow Simulations in 3D Unstructured Grids over an Acoustic Cavity

Araya

2024

Fluids

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In this study, the unsteady Reynolds-averaged Navier–Stokes (URANS) equations are employed in conjunction with the Menter Shear Stress Transport (SST)-Scale-Adaptive Simulation (SAS) turbulence model in compressible flow, with an unstructured mesh and complex geometry. While other scale-resolving approaches in space and time, such as direct numerical simulation (DNS) and large-eddy simulation (LES), supply more comprehensive information about the turbulent energy spectrum of the fluctuating component of the flow, they imply computationally intensive situations, usually performed over structured meshes and relatively simple geometries. In contrast, the SAS approach is designed according to “physically” prescribed length scales of the flow. More precisely, it operates by locally comparing the length scale of the modeled turbulence to the von Karman length scale (which depends on the local first- and second fluid velocity derivatives). This length-scale ratio allows the flow to dynamically adjust the local eddy viscosity in order to better capture the large-scale motions (LSMs) in unsteady regions of URANS simulations. While SAS may be constrained to model only low flow frequencies or wavenumbers (i.e., LSM), its versatility and low computational cost make it attractive for obtaining a quick first insight of the flow physics, particularly in those situations dominated by strong flow unsteadiness. The selected numerical application is the well-known M219 three-dimensional rectangular acoustic cavity from the literature at two different free-stream Mach numbers, M∞ (0.85 and 1.35) and a length-to-depth ratio of 5:1. Thus, we consider the “deep configuration” in experiments by Henshaw. The SST-SAS model demonstrates a satisfactory compromise between simplicity, accuracy, and flow physics description.

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Numerical Investigation of the Flow Structure and Acoustical Noise in a Suppressor

Ayaliew Yimam,

Demircan

2024

Fluct. Noise Lett.

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The noise created when a firearm is fired has a lot of adverse effects on humans and the environment, so analyzing and attenuating this noise is essential. This study aimed to examine propellant flow and the sound generated by this flow using a hybrid computational fluid dynamics and computational aeroacoustics method. The compatibility of this numerical study was also validated by comparing it with the experimental result. The impact of critical parameters, such as the shape and number of baffles of the suppressor, was studied. Finally, the overpressure and acoustics results of different suppressors were compared with each other and with the unsuppressed condition. According to the result, the suppressor with curved baffles shows a better performance. When the exit pressure at the tip of suppressor compared to the initial inlet pressure to the suppressor the percentage drop in overpressure was 76.01%, 78.79% and 81.3% for the suppressor with one, three and five curved baffles, respectively. For condition without suppressor, 169.49[Formula: see text]dB of SPL was recorded. When using a suppressor without a baffle, this value was reduced to 162.13[Formula: see text]dB. For the suppressor with one, three and five curved baffles, the SPL value was 160.234[Formula: see text]dB, 159.43[Formula: see text]dB and 158.11[Formula: see text]dB, respectively. Generally, this study shows that the suppressor’s efficiency is directly proportional to its shape and number of baffles.

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Assessment of Turbulence Models over a Curved Hill Flow with Passive Scalar Transport

Cited by 4 publications

References 35 publications

Unsteady Subsonic/Supersonic Flow Simulations in 3D Unstructured Grids over an Acoustic Cavity

Unsteady Subsonic/Supersonic Flow Simulations in 3D Unstructured Grids over an Acoustic Cavity

Unsteady Subsonic/Supersonic Flow Simulations in 3D Unstructured Grids over an Acoustic Cavity

Numerical Investigation of the Flow Structure and Acoustical Noise in a Suppressor

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