Direct and adjoint global stability analysis of turbulent transonic flows over a NACA0012 profile

In this work, various turbulent solutions of the two-dimensional (2D) and three-dimensional compressible Reynolds averaged Navier?Stokes equations are analyzed using global stability theory. This analysis is motivated by the onset of flow unsteadiness (Hopf bifurcation) for transonic buffet conditions where moderately high Reynolds numbers and compressible effects must be considered. The buffet phenomenon involves a complex interaction between the separated flow and a shock wave. The efficient numerical methodology presented in this paper predicts the critical parameters, namely, the angle of attack and Mach and Reynolds numbers beyond which the onset of flow unsteadiness appears. The geometry, a NACA0012 profile, and flow parameters selected reproduce situations of practical interest for aeronautical applications. The numerical computation is performed in three steps. First, a steady baseflow solution is obtained; second, the Jacobian matrix for the RANS equations based on a finite volume discretization is computed; and finally, the generalized eigenvalue problem is derived when the baseflow is linearly perturbed. The methodology is validated predicting the 2D Hopf bifurcation for a circular cylinder under laminar flow condition. This benchmark shows good agreement with the previous published computations and experimental data. In the transonic buffet case, the baseflow is computed using the Spalart?Allmaras turbulence model and represents a mean flow where the high frequency content and length scales of the order of the shear-layer thickness have been averaged. The lower frequency content is assumed to be decoupled from the high frequencies, thus allowing a stability analysis to be performed on the low frequency range. In addition, results of the corresponding adjoint problem and the sensitivity map are provided for the first time for the buffet problem. Finally, an extruded three-dimensional geometry of the NACA0012 airfoil, where all velocity components are considered, was also analyzed as a Triglobal stability case, and the outcoming results were compared to the previous 2D limited model, confirming that the buffet onset is well detected.

Validation of the Swiss methane emission inventory by atmospheric observations and inverse modelling

Atmospheric inverse modelling has the potential to provide observation-based estimates of greenhouse gas emissions at the country scale, thereby allowing for an independent validation of national emission inventories. Here, we present a regional-scale inverse modelling study to quantify the emissions of methane (CH₄) from Switzerland, making use of the newly established CarboCount-CH measurement network and a high-resolution Lagrangian transport model. In our reference inversion, prior emissions were taken from the "bottom-up" Swiss Greenhouse Gas Inventory (SGHGI) as published by the Swiss Federal Office for the Environment in 2014 for the year 2012. Overall we estimate national CH₄ emissions to be 196 ± 18 Gg yr⁻¹ for the year 2013 (1σ uncertainty). This result is in close agreement with the recently revised SGHGI estimate of 206 ± 33 Gg yr⁻¹ as reported in 2015 for the year 2012. Results from sensitivity inversions using alternative prior emissions, uncertainty covariance settings, large-scale background mole fractions, two different inverse algorithms (Bayesian and extended Kalman filter), and two different transport models confirm the robustness and independent character of our estimate. According to the latest SGHGI estimate the main CH₄ source categories in Switzerland are agriculture (78 %), waste handling (15 %) and natural gas distribution and combustion (6 %). The spatial distribution and seasonal variability of our posterior emissions suggest an overestimation of agricultural CH₄ emissions by 10 to 20 % in the most recent SGHGI, which is likely due to an overestimation of emissions from manure handling. Urban areas do not appear as emission hotspots in our posterior results, suggesting that leakages from natural gas distribution are only a minor source of CH₄ in Switzerland. This is consistent with rather low emissions of 8.4 Gg yr⁻¹ reported by the SGHGI but inconsistent with the much higher value of 32 Gg yr⁻¹ implied by the EDGARv4.2 inventory for this sector. Increased CH₄ emissions (up to 30 % compared to the prior) were deduced for the north-eastern parts of Switzerland. This feature was common to most sensitivity inversions, which is a strong indicator that it is a real feature and not an artefact of the transport model and the inversion system. However, it was not possible to assign an unambiguous source process to the region. The observations of the CarboCount-CH network provided invaluable and independent information for the validation of the national bottom-up inventory. Similar systems need to be sustained to provide independent monitoring of future climate agreements.

Contaminants associated with direct and indirect reuse of municipal wastewater /

Contract 68-02-2257.

Path integral calculation of the three-particle direct and exchange contributions to the pair distribution function and of the third virial coefficient for He4 gas /

Thesis--Illinois.

Theoretical and practical electrical engineering; comprising a course of lectures given at the Bliss Electrical School upon the principles and applications of both direct and alternating current apparatus

Mode of access: Internet.

Amalgamated clothing workers of America and Men's clothing manufacturers associations. Board of arbitration, Chicago. Hart, Schaffner & Marx labor agreement, Chicago. Cases decided by the Board of arbitration, direct and appealed, 1913-1925.

Multigraphed.

Direct and indirect emissions production by urban truck movement in the Chicago region /

"Project no. 10.082."

Leigh's new pocket road-book of England and Wales, containing an account of all the direct and cross roads ...

Mode of access: Internet.

Leigh's new pocket road-book of Ireland : containing an account of all the direct and cross roads, together with a description of every remarkable place ...

Goldsmiths'-Kress no. 28937.

Paterson's roads; being an entirely original and accurate description of all the direct and principal cross roads in England and Wales, with part of the roads of Scotland.

Mode of access: Internet.

Cary's New itinerary: or, An accurate delineation of the great roads, : both direct and cross, throughout England and Wales; with many of the principal roads in Scotland. /

Includes indexes.

Paterson's British itinerary : being a new and accurate delineation and description of the direct and principal cross roads of Great Britain /

Goldsmiths'-Kress no. 19452.1.

A new and accurate description of all the direct and principal cross roads in England and Wales ...

Master microform held by: ResP.

Cary's new itinerary : or, An accurate delineation of the great roads, both direct and cross, throughout England and Wales ; with many of the principal roads in Scotland. From an actual admeasurement by John Cary, made by command of his Majesty's Postmaster General for official purposes under the direction and inspection of Thomas Hasker ...

Mode of access: Internet.

Organizational, intermediate (field), (direct and general support), and depot maintenance repair parts and special tools list : engine, gasoline, 6 HP, military standard models, DOD model 4A032-1, 4A032-2, NSN 2805-00-776-0483, 2805-00-068-7512.

"April 1977."