Numerical coupling procedure in steady conjugate heat transfer problems

This paper analyses the numerical stability of a coupling procedure between a CFD code and a conduction solver in a partitioned approach. A finite volume method is used in the fluid partition and a finite element method in the solid partition. Since our goal is to get a global fluid-solid solution, the analysis of the transient in the solid is not of particular interest. Consequently, the numerical method is based on the coupling of a steady state in the solid with a time-dependent solution in the fluid. At the shared interface, Dirichlet (on the fluid side) and Robin (on the solid side) conditions are applied. An interface stability study is performed according to the normal-mode analysis of the theory of Godunov-Ryabenkii. The existence of an optimal coupling parameter is highlighted

Le Calcaire de Givetien à Givet

The authors recount the original definitions and the evolution of the conceptions of the Giuet Limestone and the Givetian at Givet. In order to end the existing confusion they define a Givet Group composed of three formations, which are, from base to top : Trois-Fontaines, Mont d'Haurs and Fromelennes Formations.Each of these formations corresponds to a third order positive-negative bisequence (marine facies - sabkha - marine facies), while second order sequences permit the recognition of thirty-two major phases which indicate the following environments : detrital and non-turbulent in the euphotic zone, reef, lagoon and of sabkha; minor first order sequences are recognized in those major phases.As for the Givetian, the authors make suggestions to be eventually examined by international bodie

The performance of beams and columns continuously braced with diaphragms - I

When properly attached, shear-rigid light-gage metal diaphragms, such as roof decking or wall sheathing, can be very effective as lateral bracing for slender columns and beams. At present, limited design use is made of this fact, because of inadequate information on the effectiveness and reliability of such bracing. In this thesis, previous theory on the stability of Isection beams and columns braced with shear-rigid diaphragms has been extended. Two energy methods are used, one employing the Euler-Lagrange conditions from the calculus of variations, and the other the Rayleigh-Ritz method. The problem initially considered is that of an I-section beam-column eccentrically loaded in the plane of the web. This problem is later reduced to two extreme conditions, a column centrally loaded, and a beam sUbjected to uniform bending moment, for which explicit solutions are obtained. A method for handling the beam-column problem is indicated. For a centrally loaded elastic column with continuous shear-rigid bracing symmetrically disposed with respect to the column centroid, previous investigators have determined the augmented weak-axis buckling load as p = pyy + Q where Pyy is the weak-axis buckling load of the unbraced column, and Q is the effective shear rigidity of the bracing. In this investigation, a theoretical solution is obtained for centrally loaded columns with a single diaphragm at any location, considering possible twist of the column. A solution for the torsional-flexural buckling load for centrally loaded columns symmetrically braced by diaphragms is presented also. In addition, previous results for diaphragm-braced columns buckling into multiple half sine waves are modified, and a solution is obtained for buckling of diaphragm-braced columns with an enforced axis of rotation. For diaphragm-braced beams subjected to uniform bending moment, theoretical results are presented for both simply supported end conditions (ends fixed against rotation about the longitudinal axis only), and for ends fixed also against lateral displacement. Inelastic behavior of diaphragm-braced beams and columns is considered. Theoretical results are compared with 16 tests of concentrically loaded double-column assemblies, and 5 tests of diaphragm-braced dOUble-beam assemblies subjected to uniform bending moment. For columns in the elastic range, test results are consistently about 10 percent below predicted values, while the magnitude of the increase over the unbraced strength is several-fold. It is shown that diaphragm bracing can reliably increase the carrying capacity of slender columns up to the elastic limit load. Above the elastic limit load, the influence of diaphragm bracing is much less pronounced, and somewhat less predictable. For beams in the elastic range, test results exceed predicted values obtained neglecting the cross-bending rigidity of the diaphragms, again with a several-fold increase in carrying capacity. The yield moment of beams appears to be readily attainable using shear-rigid diaphragm bracing

The performance of beams and columns continuously-braced with diaphragms

INTRODUCTION Under the general title of Performance of Steel-Framed Buildings and Structural Members Braced with Light-Gage Steel Diaphragms , sponsored at Cornell University by the American Iron and Steel Institute, an investigation has been proceeding in two separate but closely interrelated phases, referred to as: Subproject A - Performance of Steel-Framed Buildings Braced with Light-Gage Steel Diaphragms Subproject B - Performance of Beams and Columns Continuously-Braced with Diaphragms. The investigation now referred to as Subproject B was sponsored by the American Institute of Steel Construction from June, 1961 to June, 1963 after which A.I.S.I. assumed sponsorship with the cooperation of A.I.S.C. The summary report covering the first two years\u27 investigation is The Performance of Beams and Columns Continuously-Braced with Diaphragms , Third Progress Report by Fisher and Pincus, Report No.313, Department of Structural Engineering, School of Civil Engineering, Cornell University, September 1963, hereafter referred to as the Third Progress Report. Investigations to date have covered two general areas: (a) the general characteristics of shear diaphragms, with special reference to shear rigidity, and (b) the performance of diaphragm-braced columns. While a small number of additional double-column tests remain to be performed, Subproject B is essentially at the point of completion of column studies and the initiation of tests on diaphragm-braced beams. Unexpected difficulties in staffing and materials supply have resulted in some unavoidable delays, but there is considerable reason to expect that the beam studies can be substantially completed by the end of the present contract period, May 1965. This present report, to be known as the Fourth Progress Report. covers investigations for the period approximately October 1, 1963 to August 15, 1964. During this reporting period, work has progressed in three related areas: (1) improvement of understanding of diaphragm behavior, (2) inelastic behavior of diaphragm-braced columns, and (3) plans for tests on diaphragm-braced beams. Each of these will be discussed in detail in the following sections of the report. Effective shear modulus of corrugated diaphragms, as determined under Subproject B by means of double-beam assemblies (see Third Progress Report), has been correlated experimentally and, with partial success, theoretically with the shear modulus as determined under Subproject A by means of rectangular frame tests. Practically identical experimental results are obtained by both kinds of tests for small size diaphragms. In addition, the results for the large diaphragms of Subproject A have been correlated also with the small diaphragm results to a substantial degree. Cooperation between the two subprojects, therefore, has provided considerably more generality and certainty of diaphragm behavior than heretofore available. An empirical expression for the shear modulus of standard (and similar) corrugated sheets has been developed. To this end, four additional double-beam shear tests have been performed. Two additional double-column tests have been performed and a better empirical expression for prediction of failure loads of diaphragm-braced columns in the inelastic range has been developed. Planning for the projected diaphragm-braced beam phase of the program is well under way, including studies of suitable beam sections, range of beam slenderness, and details of the test setup

Aero-thermo-mechanical coupling for flame-wall interaction

This paper investigates a flame-wall interaction consisting of a premixed flame impinging on a metallic plate. This is a coupled problem as the heat transfer from the flame increases the temperature of the plate and bends it, which in turn modifies the shape of the flame. This study aims at designing an aero-thermo-mechanical coupling between both codes CEDRE (Computational Fluid Dynamics) and Z-SeT (computational solid mechanics and heat conduction) to simulate this complex system. Numerical results for aero-thermal coupling are compared with experimental data

Harmonisation and diagnostics of MIPAS ESA CH4 and N2O profiles using data assimilation

This paper discusses assimilation experiments of methane (CH4) and nitrous oxide (N2O) profiles retrieved from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). Here we focus on data versions 6 and 7 provided by the ESA processor. These data sets have been assimilated by the Belgian Assimilation System for Chemical ObsErvations (BASCOE). The CH4 and N2O retrieved profiles can oscillate, especially in the tropical lower stratosphere. Using the averaging kernels of the observations and a background error covariance matrix, which has previously been calibrated, allows the system to partly remedy this issue and provide assimilated fields that are more regular vertically. In general, there is a good agreement between the BASCOE analyses and independent observations from ACE–FTS (CH4 and N2O) and MLS (N2O), demonstrating the general good quality of CH4 and N2O retrievals provided by MIPAS ESA. Nevertheless, this study also identifies two issues in these data sets. First, time series of the observations show unexpected discontinuities due to an abrupt change in the gain of MIPAS band B, generally occurring after the instrument decontamination. Since the calibration is performed weekly, the abrupt change in the gain affects the measurements until the subsequent calibration is performed. Second, the correlations between BASCOE analyses and independent observations are poor in the lower stratosphere, especially in the tropics, probably due to the presence of outliers in the assimilated data. In this region, we recommend using MIPAS CH4 and N2O retrievals with caution

Global observations of tropospheric BrO columns using GOME-2 satellite data

Measurements from the GOME-2 satellite instrument have been analyzed for tropospheric BrO using a residual technique that combines measured BrO columns and estimates of the stratospheric BrO content from a climatological approach driven by O<sub>3</sub> and NO<sub>2</sub> observations. Comparisons between the GOME-2 results and BrO vertical columns derived from correlative ground-based and SCIAMACHY nadir observations, present a good level of consistency. We show that the adopted technique enables separation of stratospheric and tropospheric fractions of the measured total BrO columns and allows quantitative study of the BrO plumes in polar regions. While some satellite observed plumes of enhanced BrO can be explained by stratospheric descending air, we show that most BrO hotspots are of tropospheric origin, although they are often associated to regions with low tropopause heights as well. Elaborating on simulations using the <i>p</i>-TOMCAT tropospheric chemical transport model, this result is found to be consistent with the mechanism of bromine release through sea salt aerosols production during blowing snow events. No definitive conclusion can be drawn however on the importance of blowing snow sources in comparison to other bromine release mechanisms. Outside polar regions, evidence is provided for a global tropospheric BrO background with column of 1–3 × 10<sup>13</sup> molec cm<sup>−2</sup>, consistent with previous estimates