Inner–outer interactions in a forced plane wall jet

Artham, Sravankumar; Zhang, Zheng; Gnanamanickam, Ebenezer P.

doi:10.1007/s00348-021-03136-4

Cited by 5 publications

(4 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The forcing is hypothesized to amplify the energy transfer mechanisms already existing in unforced wall jets. Artham, Zhang & Gnanamanickam (2021) study the amplitude and frequency modulation with and without large-scale forcing in the same flow as Gnanamanickam et al and Bhatt & Gnanamanickam. Their results indicate that the large-scale energy in the wall region increases significantly as a result of excitation.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of the structure of plane turbulent wall jets. Part 1. Spectral analysis

Choudhary,

Gupta,

Bhatt

et al. 2024

J. Fluid Mech.

View full text Add to dashboard Cite

Plane turbulent wall jets are traditionally considered to be composed of a turbulent boundary layer (TBL) topped by a half-free jet. However, certain peculiar features, such as counter-gradient momentum flux occurring below velocity maximum in experiments and numerical simulations, suggest a different structure of turbulence therein. Here, we hypothesize that turbulence in wall jets has two distinct structural modes, wall mode scaling on wall variables and free-jet mode scaling on jet variables. To investigate this hypothesis, experimental data from our wall jet facility are acquired using single hot-wire anemometry and two-dimensional particle image velocimetry at three nozzle Reynolds numbers 10 244, 15 742 and 21 228. Particle image velocimetry measurements with four side-by-side cameras capture the longest field of view studied so far in wall jets. Direct spatial spectra of these fields reveal modal spectral contributions to variances of velocity fluctuations, Reynolds shear stress, shear force, turbulence production, velocity fluctuation triple products and turbulent transport. The free-jet mode has wavelengths scaling on the jet length scale ${z_{T}}$ , and contains two dominant submodes with wavelengths $5{z_{T}}$ and $2.5{z_{T}}$ . The region of flow above the velocity maximum shows the presence of the outer jet mode whereas the region below it shows robust bimodal behaviour attributed to both wall and inner jet modes. Counter-gradient momentum flux is effected by the outer jet mode intruding into the region below velocity maximum. These findings support the hypothesis of wall and free-jet structural modes, and indicate that the region below velocity maximum could be much complex than a conventional TBL.

show abstract

Section: Introductionmentioning

confidence: 99%

Experimental investigation of the structure of plane turbulent wall jets. Part 1. Spectral analysis

Choudhary,

Gupta,

Bhatt

et al. 2024

J. Fluid Mech.

View full text Add to dashboard Cite

show abstract

“…Temporal periodic perturbations can be also introduced by a wall jet [17,18] or a wall-mounted piezoelectric actuator [19][20][21]. Instead of introducing the perturbation very close to the wall, Ranade et al [22] performed an experimental study where they introduced the perturbation outside (above) the boundary layer.…”

Section: Introductionmentioning

confidence: 99%

Spatial input-output analysis of large-scale structures in actuated turbulent boundary layers

Liu

Gluzman

Lozier

et al. 2022

Preprint

View full text Add to dashboard Cite

This paper develops a spatial input-output approach to investigate the dynamics of a turbulent boundary layer subject to a localized single frequency excitation. This method uses one-way spatial integration to reformulate the problem in terms of spatial evolution equations. The technique is used to examine the effect of localized periodic actuation at a given temporal frequency, based on an experimental set-up in which an active large-scale is introduced into the outer layer of a turbulent boundary layer. First, the large-scale structures associated with the phase-locked modal velocity field obtained from spatial input-output analysis are shown to closely match those computed based on hot-wire measurements. The approach is then used to further investigate the response of the boundary layer to the synthetically generated large-scale. A quadrant trajectory analysis indicates that the spatial input-output response produces shear stress distributions consistent with those in canonical wall-bounded turbulent flows in terms of both the order and types of events observed. The expected correspondence between the dominance of different quadrant behavior and actuation frequency is also observed. These results highlight the promise of a spatial input-output framework for analyzing the formation and streamwise evolution of structures in actuated wall-bounded turbulent flows. Nomenclature 𝑥 = streamwise location 𝑦 = wall-normal location 1 Graduate student, Department of Mechanical Engineering.

show abstract

“…More recent investigations address the complex nature of this flow that is governed by different types of coherent structures according to Gnanamanickam et al (2019). Among those, forward-leaning flow structures have been revealed as the main source of an interaction between the inner and outer regions that are separated by the location of maximum streamwise velocity (Bhatt & Gnanamanickam 2020;Artham, Zhang & Gnanamanickam 2021).…”

Section: Introductionmentioning

confidence: 99%

“…(2019). Among those, forward-leaning flow structures have been revealed as the main source of an interaction between the inner and outer regions that are separated by the location of maximum streamwise velocity (Bhatt & Gnanamanickam 2020; Artham, Zhang & Gnanamanickam 2021).…”

Section: Introductionmentioning

confidence: 99%

Modelling the decay of finite-span starting and stopping wall jets in an external stream

Steinfurth

Weiss

2022

J. Fluid Mech.

View full text Add to dashboard Cite

The flow under consideration is a wall jet that results from an inclined jet in cross-flow emitted into a zero-pressure-gradient turbulent boundary layer from a slot-like outlet of width $b=0.5\,\mathrm {mm}$ and span $L=20\,\mathrm {mm}$ . Despite the finite jet span, the velocity decay and wall-normal spreading rate in the symmetry plane can be described with power laws almost identical to those for the two-dimensional flow determined by Zhou & Wygnanski (AIAA J., vol. 31, 1993, pp. 848–853). This is explained by the lack of significant lateral spreading found in the present configuration due to a self-amplifying inward-directed fluid motion, fundamentally differing from conditions found in the absence of an external stream. Regions with ‘approximately self-similar’ properties also exist in the case of unsteady velocity programmes where the fluid is ejected in a pulsatile fashion. Here, the wall jet is enclosed by a leading vortex structure and a deceleration wave, for which the time-dependent locations can be predicted by means of empirical constants. This yields models for the major properties inside the advancing and diffusing wall jet that only require knowledge regarding the velocity ratio, the ejected momentum flux and the kinematic viscosity, representing an extension to scaling laws for steady wall jets in still ambience established by Narasimha et al. (Aeronaut. Q., vol. 77, 1973, pp. 355–359).

show abstract

Inner–outer interactions in a forced plane wall jet

Cited by 5 publications

References 41 publications

Experimental investigation of the structure of plane turbulent wall jets. Part 1. Spectral analysis

Experimental investigation of the structure of plane turbulent wall jets. Part 1. Spectral analysis

Spatial input-output analysis of large-scale structures in actuated turbulent boundary layers

Modelling the decay of finite-span starting and stopping wall jets in an external stream

Contact Info

Product

Resources

About