1,720,964 research outputs found
Dataset for Large-Eddy Simulations and modal reconstruction of laminar transonic buffet
No full textThis dataset corresponds to several plots presented in the article, "Large-Eddy Simulations and modal reconstruction of laminar transonic buffet" published in the Journal of Fluid Mechanics, 2022. Plots with aerofoil geometry are not provided due to copyright reasons. All files are in ASCII format and named in a "fig[No][subfigure][description].csv" format (e.g. fig30d_X.csv refers to figure 30d in the article with X being the variable stored). Line plots are stored such that columns correspond to x- and y-axis with a header specifying details in a string format. Contour plots contain mesh arrays named based on figure labels (e.g. X and T) and a variable of the same array dimension.</span
Dataset for the journal article 'Connecting transonic buffet with incompressible low-frequency oscillations on aerofoils'
No full textThis dataset corresponds to figures presented in the article, "Connecting transonic buffet with incompressible low-frequency oscillations on aerofoils" published in the Journal of Fluid Mechanics, 2024. Plots with aerofoil geometry are not provided due to copyright reasons. All files are in a 'comma-separated variable' format and named in a "fig[No][subfigure]_[description].csv" format (e.g. fig2a_M0p60.csv refers to figure 2a in the article with M0p6 representing data for M=0.6). Line plots are stored such that columns correspond to x- and y-axis with a header specifying details in a string format. Figures included: 2a,3a,5a,b,6a,b,8a,b,10a,b,11a,b,14a,b,19a,b,22a,b</span
Large Eddy Simulations and modal reconstruction of laminar transonic buffet
Full text linkTransonic buffet refers to the self-sustained periodic motion of shock waves
observed in transonic flows over wings and limits the flight envelope of
aircraft. Based on the boundary layer characteristics at the shock foot, buffet
has been classified as laminar or turbulent and the mechanisms underlying the
two have been proposed to be different (Dandois et al., 2018, J. Fluid Mech.,
vol. 18, pp. 156-178). The effect of various flow parameters (freestream Mach
and Reynolds numbers and sweep and incidence angles) on laminar transonic
buffet on an infinite wing (Dassault Aviation's supercritical V2C aerofoil) is
reported here by performing Large-Eddy Simulations (LES) for a wide range of
parameters. A spectral proper orthogonal decomposition identified the presence
of a low-frequency mode associated with buffet and high-frequency wake modes
related to vortex shedding. A flow reconstruction based only on the former
shows periodic boundary-layer separation and reattachment accompanying shock
wave motion. A modal reconstruction based only on the wake mode suggests that
the separation bubble breathing phenomenon reported by Dandois et al. is due to
this mode. Together, these results indicate that the physical mechanisms
governing laminar and turbulent buffet are the same. Buffet was also simulated
at zero incidence. Shock waves appear on both aerofoil surfaces and oscillate
out of phase with each other indicating the occurrence of a Type I buffet
(Giannelis et al., 2018, Aerosp. Sci. Technol., vol. 18, pp. 89-101) on a
supercritical aerofoil. These results suggest that the mechanisms underlying
different buffet types are the same.Comment: 40 pages, 31 figures, submitted to Journal of Fluid Mechanic
Dataset in support of the publication: On the co-existence of transonic buffet and separation-bubble modes for the OALT25 laminar-flow wing section
No full textData-set corresponding to the publication:
"On the co-existence of transonic buffet and separation-bubble modes for the OALT25 laminar-flow wing section"
Markus Zauner, Pradeep Moise, Neil D. Sandham
Journal of Flow Turbulence and Combustion (2023)
10.1007/s10494-023-00415-4
https://link.springer.com/article/10.1007/s10494-023-00415-4</span
Connecting transonic buffet with incompressible low-frequency oscillations on aerofoils
No full textSelf-sustained, low-frequency, coherent flow unsteadiness over rigid, stationary aerofoils in the transonic regime is referred to as transonic buffet. This study examines the role of shock waves in sustaining this transonic phenomenon and its relation to low-frequency oscillations that occur in flow over aerofoils in the incompressible regime (Zaman et al., 1989, J. Fluid Mech., vol. 202, pp. 403–442). This is investigated by performing large-eddy simulations of the flow over a NACA0012 profile for a wide range of flow conditions under free-transition conditions. At low Reynolds numbers, zero incidence angle and sufficiently high freestream Mach numbers
Transonic buffet characteristics under conditions of free and forced transition
No full textTransonic buffet is commonly associated with self-sustained flow unsteadiness involving shockwave/boundary-layer interaction over aerofoils and wings. The phenomenon has been classified as either laminar or turbulent based on the state of the boundary layer immediately upstream of the shock foot and distinct mechanisms for the two types have been suggested. The turbulent case is known to be associated with a global linear instability. Herein, large-eddy simulations are used for the first time to make direct comparisons of the two types by examining free and forced-transition conditions. Corresponding simulations based on the Reynolds-averaged Navier–Stokes equations for the forced-transition case are also performed for comparison with the scale-resolving approach and for linking the findings with existing literature. Coherent flow features are scrutinised using both data-based spectral proper orthogonal decomposition of the time-marched results and operator-based global linear stability and resolvent analyses within the Reynolds-averaged Navier–Stokes framework. It is demonstrated that the essential dynamic features remain the same for the two buffet types (and for the two levels of the aerodynamic modelling hierarchy), suggesting that both types arise due to the same fundamental mechanism
Data supporting the article, "Transonic buffet characteristics under conditions of free and forced transition" published in the AIAA Journal, 2022
No full textThis dataset supports the publication by Moise, P., Zauner, M., Sandham, N. D., Timme, S. & Wei, H "Transonic Buffet Characteristics Under Conditions of Free and Forced Transition", AIAA Journal, https://doi.org/10.2514/1.J062362.
The data contains
DataSets.zip, containing ".csv" (comma separated values, CSV) files in ASCII format. These CSV files correspond to several plots presented in the article, "Transonic Buffet Characteristics Under Conditions of Free and Forced Transition" published in the AIAA Journal, 2022. Plots with aerofoil geometry are not provided due to copyright reasons. All CSV files are named in a "fig[No][subfigure][description].csv" format (e.g. fig30d_X.csv refers to figure 30d in the article with X being the variable stored). The figures for which data is provided are:
3,6,7,8,11,12,13,18,A1,B1.
A sample MATLAB script, sample Code.m is provided for plotting the data in the .csv files.
Padeep Moise is an Assistant Professor, Department of Aerospace Engineering, Indian Institute of Technology Kanpur, Uttar Pradesh 208016, India (email [email protected])
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On the co-existence of transonic buffet and separation-bubble modes for the OALT25 laminar-flow wing section
Full text linkTransonic buffet is an unsteady flow phenomenon that limits the safe flight
envelope of modern aircraft. Scale-resolving simulations with span-periodic
boundary conditions are capable of providing new insights into its flow
physics. The present contribution shows the co-existence of multiple modes of
flow unsteadiness over an unswept laminar-flow wing section, appearing in the
following order of increasing frequency: (a) a low-frequency transonic buffet
mode, (b) an intermediate-frequency separation bubble mode, and (c)
high-frequency wake modes associated with vortex shedding. Simulations are run
over a range of Reynolds and Mach numbers to connect the lower frequency modes
from moderate to high Reynolds numbers and from pre-buffet to established
buffet conditions. The intermediate frequency mode is found to be more
sensitive to Reynolds-number effects compared to those of Mach number, which is
the opposite trend to that observed for transonic buffet. Spectral proper
orthogonal decomposition is used to extract the spatial structure of the modes.
The buffet mode involves coherent oscillations of the suction-side shock
structure, consistent with previous studies including global mode analysis. The
laminar separation-bubble mode at intermediate frequency is fundamentally
different, with a phase relationship between separation and reattachment that
does not correspond to a simple `breathing' mode and is not at the same
Strouhal number observed for shock-induced separation bubbles. Instead, a
Strouhal number based on separation bubble length and reverse flow magnitude is
found to be independent of Reynolds number within the range of cases studied
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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