In this paper, we perform direct numerical simulation (DNS) of turbulent boundary layers at Mach 5 with the ratio wall-to-edge temperature T w / δ from 1.0 to 5.4 (Cases M5T1 M5T5). The influence wall cooling on Morkovin's scaling, Walz's equation, standard and modified strong Reynolds analogies, kinetic energy budgets, compressibility effects near-wall coherent structures is assessed. We find that many scaling relations used express adiabatic compressible boundary-layer statistics in terms...

In this paper, we perform direct numerical simulations (DNS) of turbulent boundary layers with nominal free-stream Mach number ranging from 0.3 to 12. The main objective is assess the scalings respect mean and turbulence behaviours as well possible breakdown weak compressibility hypothesis for at high numbers ( M > 5). We find that many scaling relations, such van Driest transformation velocity, Walz's relation, Morkovin's strong Reynolds analogy, which are derived based on hypothesis,...

By adapting reverse time migration (RTM) and demigration as the modeling operators to maximize crosscorrelation between simulated acquired seismic data, we introduced a new practical least-squares RTM (LSRTM) scheme derived steepest descent method in seeking optimal image. Through synthetic real data experiments, determined that proposed LSRTM provided high-quality images with balanced amplitudes, improved focusing, enhanced resolution. The was also capable of removing free surface ghosts...

This paper presents a direct numerical simulation database of high-speed zero-pressure-gradient turbulent boundary layers developing spatially over flat plate with nominal freestream Mach number ranging from 2.5 to 14 and wall-to-recovery temperature 0.18 1.0. The flow conditions the DNS are representative operational Purdue 6 quiet tunnel, Sandia Hypersonic Wind Tunnel at 8, AEDC Hypervelocity No. 9 14. is used gauge performance compressibility transformations, including classical...

Direct numerical simulations (DNS) are performed to investigate the spatial evolution of flat-plate zero-pressure-gradient turbulent boundary layers over long streamwise domains ( ${>}300\delta _i$ , with $\delta inflow boundary-layer thickness) at three different Mach numbers, $2.5$ $4.9$ and $10.9$ surface temperatures ranging from quasiadiabatic highly cooled conditions. The settlement turbulence statistics into a fully developed equilibrium state layer has been carefully monitored,...

Direct numerical simulations (DNS) are used to examine the pressure fluctuations generated by a spatially developed Mach 5.86 turbulent boundary layer. The unsteady field is analysed at multiple wall-normal locations, including those wall, within layer (including inner layer, log and outer layer), in free stream. statistical structural variations of as function distance highlighted. Computational predictions for mean-velocity profiles surface spectrum good agreement with experimental...

Abstract In this paper we present direct numerical simulations (DNS) of hypersonic turbulent boundary layers to study high-enthalpy effects. We high- and low-enthalpy conditions, which are representative those in flight ground-based facilities, respectively. find that closely resemble at low enthalpy. Many the scaling relations for flows, such as van-Driest transformation mean velocity, Morkovin’s modified strong Reynolds analogy hold or can be generalized flows by removing calorically...

Abstract Direct numerical simulations are used to examine the pressure fluctuations generated by fully developed turbulence in a Mach 2.5 turbulent boundary layer, with an emphasis on acoustic radiated into free stream. Single- and multi-point statistics of computed surface show good agreement measurements at similar flow conditions. Consistent spark shadowgraphs obtained flight, quasi-homogeneous near field free-stream region consists randomly spaced wavepackets finite spatial coherence....

The size of a pressure transducer is known to affect the accuracy measurements wall-pressure fluctuations beneath turbulent boundary layer because spatial averaging over sensing area transducer. In this paper, effect finite investigated by applying or wavenumber filters database hypersonic wall generated from direct numerical simulation (DNS) that simulates portion sharp 7° half-angle cone at nominally Mach 8. A good comparison between DNS and experiment in Sandia Hypersonic Wind Tunnel 8...

Conventional methods of prestack depth imaging aim at producing a structural image that delineates the interfaces geologic variations or reflectivity earth. However, it is underlying impedance and velocity changes generate this are more interest for characterizing reservoir. Indeed, need to better product interpretation leads subsequent application traditional seismic-inversion techniques sections come from typical depth-imaging processes. The drawback here these use additional information,...

Direct numerical simulations of turbulent boundary layers with a nominal free-stream Mach number $6$ and Reynolds $Re_{\unicode[STIX]{x1D70F}}\approx 450$ are conducted at wall-to-recovery temperature ratio $T_{w}/T_{r}=0.25$ compared previous database for $T_{w}/T_{r}=0.76$ in order to investigate pressure fluctuations their dependence on wall temperature. The wall-temperature widely used velocity scaling laws high-speed is consistent studies. near-wall pressure-fluctuation intensities...

Although low-disturbance ("quiet") hypersonic wind tunnels are believed to provide more reliable extrapolation of boundary-layer transition behavior from ground flight, the presently available quiet facilities limited Mach 6, moderate Reynolds numbers, low freestream enthalpy, and subscale models. As a result, only conventional ("noisy") can reproduce both numbers enthalpies flight configurations must therefore be used for vehicle test evaluation involving high number, larger This paper...

Complex interrelated mechanisms mediate the stability of hypersonic boundary layers. Simulations are used to investigate key primary and secondary instabilities, including nonparallel effects intermode phase synchronization.

PreviousNext No AccessSEG Technical Program Expanded Abstracts 2013A stable and practical implementation of least-squares reverse time migrationAuthors: Yu ZhangLian DuanYi XieYu ZhangCGG, Lian DuanCGG, Yi XieCGGhttps://doi.org/10.1190/segam2013-0577.1 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract Adapting reverse-time migration (RTM) demigration (RTDM) as the imaging modeling operators maximize...

The effect of turbulent wind-tunnel-wall boundary layers on density change measurements obtained with focused laser differential interferometry (FLDI) was studied using a detailed direct numerical simulation (DNS) the wall from Boeing/AFOSR Mach-6 Quiet Tunnel run in its noisy configuration. DNS probed an FLDI model that is capable reading three-dimensional time-varying fields and computing response. Simulated smooth boundary-layer root-mean-square (RMS) profile relative to true values by...

This study presents a direct numerical simulation (DNS) database of high-speed turbulent boundary layers (TBLs) subject to pressure gradients due parametrically varied backward-facing and forward-facing wall curvatures, with an inflow Mach number 4.9 friction Reynolds [Formula: see text] immediately before the onset curvature. The numbers are significantly higher than those reported in literature for DNS pressure-gradient TBLs. flow conditions baseline geometries representative experiments...

For this study, Improved Delayed Detached-Eddy Simulations (IDDES) were used to analyze the wake of a modified Ahmed body with varying upper and lower slants. The geometry produced constant projected vertical base area, ensuring that slant drag function pressure caused by structures. Except at extreme angles, general structures torus two pairs streamwise-oriented vortices on each slant. These strongly correlated contribution rear surfaces: As such, was minimized when most centrally aligned...