Relatório apresentado a S. Ex. o Sr. Ministro da Industria, Viação e Obras Públicas = Rapport présenté a Son Ex. M. le Ministre de l'Industrie, de la Voirie et des Travaux Publics por L. Cruls

Trata-se do "Relatório Cruls", referente à 1ª Missão Cruls (1892-1893), durante o governo Floriano Peixoto

Ground water-surface water interactions sensor technology, Savannah, Georgia, March 7-9, 2005: workshop proceedings

The Alliance for Coastal Technologies (ACT) held a Workshop on Sensor Technology for Assessing Groundwater-Surface Water Interactions in the Coastal Zone on March 7 to 9,2005 in Savannah, GA. The main goal of the workshop was to summarize the general parameters, which have been found to be useful in assessing groundwater-surface water (GW-SW) interactions in the coastal zone. The workshop participants (Appendix I) were specifically charged with identifying the types of sensor systems, if any, that have been used to obtain time-series data and to make known which parameters may be the most amenable to the development/application of sensor technology. The group consisted of researchers, industry representatives, and environmental managers. Four general recommendations were made: 1. Educate coastal managers and agencies on the importance of GW-SW interactions, keeping in mind that regulatory agencies are driven by a different set of rules than researchers: the focus is on understanding the significance of the problem and providing solutions. ACT could facilitate this process in two ways. First, given that the research literature on this subject is fairly diffuse, ACT could provide links from its web site to fact sheets or other literature. Second, ACT could organize a focused meeting for managers and/or agency groups. Encourage development of primary tools for quantifying flow. The most promising technology in this respect is flow meters designed for flux chambers, mainly because they should be simple to use and can be made relatively inexpensively. However, it should be kept in mind that they provide only point measurements and several would need to be deployed as a network in order to obtain reliable flow estimates. For evaluating system wide GW-SW interactions, tools that integrate the signal over large areas would be required. Suggestions include a user-friendly hydrogeologic models, keeping in mind that freshwater flow is not the entire story, or continuous radon monitors. Though the latter would be slightly more difficult to use in terms of background knowledge, such an instrument would be low power and easy to operate and maintain. ACT could facilitate this recommendation by identifying funding opportunities on its web site and/or performing evaluations of existing technologies that could be summarized on the web site. (pdf contains 18 pages)

Subgrid scale fluid velocity timescales seen by inertial particles in large-eddy simulation of particle-laden turbulence

Large-eddy simulation (LES) has emerged as a promising tool for simulating turbulent flows in general and, in recent years,has also been applied to the particle-laden turbulence with some success (Kassinos et al., 2007). The motion of inertial particles is much more complicated than fluid elements, and therefore, LES of turbulent flow laden with inertial particles encounters new challenges. In the conventional LES, only large-scale eddies are explicitly resolved and the effects of unresolved, small or subgrid scale (SGS) eddies on the large-scale eddies are modeled. The SGS turbulent flow field is not available. The effects of SGS turbulent velocity field on particle motion have been studied by Wang and Squires (1996), Armenio et al. (1999), Yamamoto et al. (2001), Shotorban and Mashayek (2006a,b), Fede and Simonin (2006), Berrouk et al. (2007), Bini and Jones (2008), and Pozorski and Apte (2009), amongst others. One contemporary method to include the effects of SGS eddies on inertial particle motions is to introduce a stochastic differential equation (SDE), that is, a Langevin stochastic equation to model the SGS fluid velocity seen by inertial particles (Fede et al., 2006; Shotorban and Mashayek, 2006a; Shotorban and Mashayek, 2006b; Berrouk et al., 2007; Bini and Jones, 2008; Pozorski and Apte, 2009).However, the accuracy of such a Langevin equation model depends primarily on the prescription of the SGS fluid velocity autocorrelation time seen by an inertial particle or the inertial particle–SGS eddy interaction timescale (denoted by $\delt T_{Lp}$ and a second model constant in the diffusion term which controls the intensity of the random force received by an inertial particle (denoted by C_0, see Eq. (7)). From the theoretical point of view, dTLp differs significantly from the Lagrangian fluid velocity correlation time (Reeks, 1977; Wang and Stock, 1993), and this carries the essential nonlinearity in the statistical modeling of particle motion. dTLp and C0 may depend on the filter width and particle Stokes number even for a given turbulent flow. In previous studies, dTLp is modeled either by the fluid SGS Lagrangian timescale (Fede et al., 2006; Shotorban and Mashayek, 2006b; Pozorski and Apte, 2009; Bini and Jones, 2008) or by a simple extension of the timescale obtained from the full flow field (Berrouk et al., 2007). In this work, we shall study the subtle and on-monotonic dependence of $\delt T_{Lp}$ on the filter width and particle Stokes number using a flow field obtained from Direct Numerical Simulation (DNS). We then propose an empirical closure model for $\delta T_{Lp}$. Finally, the model is validated against LES of particle-laden turbulence in predicting single-particle statistics such as particle kinetic energy. As a first step, we consider the particle motion under the one-way coupling assumption in isotropic turbulent flow and neglect the gravitational settling effect. The one-way coupling assumption is only valid for low particle mass loading.