Numerical evidence of an undisturbed region of flow in a turbulent rectangular submerged free jet

Boghi, Andrea; Angelino, Matteo; Gori, Fabio

doi:10.1080/10407782.2016.1139986

Cited by 16 publications

(44 citation statements)

References 44 publications

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“…This is the main difference with the numerical results of the two-dimensional case, [1], where this region is not present, but the large eddies occupy the entire domain, forming an asymmetric pattern. The comparison of the present results with the two-dimensional case, [1], confirm that also in presence of a perturbation in the amplitude of the velocity profile there is a Negligible Disturbance Flow (NDF), immediately downstream the slot exit, where the jet height remains almost constant, followed by the Small Disturbance Flow (SDF), where the jet height evidences small contractions or expansions but without the formation of vortices, as observed experimentally in [20]. The sum of the length of NDF and SDF is about the same of the Undisturbed Region of Flow (URF), which has been defined for the average variables.…”

Section: Instantaneous Variablescontrasting

confidence: 48%

“…free jet, at several Reynolds numbers, which extends the two-dimensional approach, [1], in order to show that also in the three-dimensional case it is possible to define self-similar relations for the URF, and to asses that the theoretical model is valid also in presence of a turbulent profile on the slot exit.…”

Section: This Work Presents the Results Of Three-dimensional (3d) Larmentioning

confidence: 99%

“…From the numerical results shown in Figs. 1-2, it is clear that, despite the presence of the 1% disturbance on the velocity profile at the slot exit, a region of flow free of vortices is present, as in [1], where the inlet profile was flat without turbulence. The instantaneous fields are variable and cannot be employed to identify the average length of the regions of flow.…”

Section: Instantaneous Variablesmentioning

confidence: 99%

“…From the two average turbulent variables, i.e. k and u v ′ ′, it is possible to distinguish two different behaviors in the near-field region, already analyzed in [1], plus a third one in the far-field, which was not captured in the 2D simulations of [1] because of the lack of vortex stretching.…”

Section: Average Variablesmentioning

confidence: 99%

“…The study preceding the present work, from the same authors, [1], has been carried out with a series of Large Eddy Simulations (LES) at several Reynolds numbers, to verify that the URF occurs in the conditions previously given by the literature [2] in a two-dimensional case.…”

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confidence: 99%

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Numerical solution of three-dimensional rectangular submerged jets with the evidence of the undisturbed region of flow

Angelino

Boghi

Gori

2016

Numerical Heat Transfer, Part A: Applications

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Section: Instantaneous Variablescontrasting

confidence: 48%

Section: This Work Presents the Results Of Three-dimensional (3d) Larmentioning

confidence: 99%

Section: Instantaneous Variablesmentioning

confidence: 99%

Section: Average Variablesmentioning

confidence: 99%

mentioning

confidence: 99%

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Numerical solution of three-dimensional rectangular submerged jets with the evidence of the undisturbed region of flow

Angelino

Boghi

Gori

2016

Numerical Heat Transfer, Part A: Applications

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Influence of grid resolution on the spectral characteristics of noise radiated from turbulent jets: Sound pressure fields and their decomposition

2020

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Jet noise remains a key target for aircraft noise reduction in the foreseeable future. While being extremely challenging, the requirement of predicting both low and high frequency noise spectra is increasingly important for design purposes. Novel approaches are needed to overcome the current numerical limitations in capturing the required broad noise spectra. Once su ciently resolved, the energy contents of the numerically simulated near-and far-field sound pressure have intrinsic correlations among di↵erent levels of grid resolution. The present work explores the potential of such correlations to broaden the spectral prediction. The noise radiated from high subsonic turbulent jets is investigated using large-eddy simulation. The 3-D filtered compressible Navier-Stokes solutions are obtained for an axisymmetric and a serrated nozzle on successively refined multi-resolution grids, ranging from 5 to 80 million grid points. The radiated far-field sound is computed using the Ffowcs Williams -Hawkings (FW-H) surface integral method. Fourier decomposition for pressure near-field is applied to help identify the location of the sound source regions and the dominant directions of propagation, which provides a more thorough understanding of the e↵ect of the grid resolution on the numerical cut-o↵ frequencies of the far-field spectra. Further analysis of the far-field spectra and of their azimuthal modes confirms that a novel strategy to obtain a broadened overall sound spectrum is possible, at reduced computational cost, from a combination of multiple spectra from successively refined grids.

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Passive scalar diffusion in three-dimensional turbulent rectangular free jets with numerical evaluation of turbulent Prandtl/Schmidt number

Venuta

Boghi

Angelino

et al. 2018

International Communications in Heat and Mass Transfer

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The passive scalar spreading of fluids with laminar Prandtl or Schmidt number, , Pr Sc , equal to 1 in turbulent rectangular submerged free jets is analyzed by means of numerical simulation and theoretical analysis in the Reynolds number range 5000-40,000. The numerical investigation is carried out by means of a three-dimensional (3D) Large Eddy Simulation (LES) approach with the dynamic Smagorinsky model. A new mathematical model allows to obtain a simplified description of the passive scalar spreading in the largest area of the flow field, the Fully Developed Region (FDR). The present three-dimensional (3D) investigation shows that the passive scalar spreading follows a self-similarity law in the Fully Developed Region (FDR), as well as in the mean Undisturbed Region of Flow (URF) and in the Potential Core Region (PCR), similarly to what found in the Near Field Region (NFR) of rectangular submerged free jets, investigated with a two-dimensional (2D) approach. The turbulent Prandtl or Schmidt number is evaluated numerically and is found to be inversely proportional to the mean velocity gradient in the PCR. The present 3D numerical results show that the turbulent Prandtl or Schmidt number is zero in most part of the mean URF, and PCR, while it assumes different values outside. In the FDR the turbulent Prandtl or Schmidt number is constant and approximately equal to 0.7, in agreement with the literature, showing that turbulence affects momentum and passive scalar in a different way.

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Numerical evidence of an undisturbed region of flow in a turbulent rectangular submerged free jet

Cited by 16 publications

References 44 publications

Numerical solution of three-dimensional rectangular submerged jets with the evidence of the undisturbed region of flow

Numerical solution of three-dimensional rectangular submerged jets with the evidence of the undisturbed region of flow

Influence of grid resolution on the spectral characteristics of noise radiated from turbulent jets: Sound pressure fields and their decomposition

Passive scalar diffusion in three-dimensional turbulent rectangular free jets with numerical evaluation of turbulent Prandtl/Schmidt number

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