1,721,254 research outputs found
Lyth bound, eternal inflation, and future cosmological missions
Full text linkIn this paper we provide a new expression for the variation of the inflaton field Δφ during the horizon crossing epoch in the context of single field slow roll inflationary models. Such an expression represents a generalization of the well-known Lyth bound. We also explore the consequences of a detection of permille order of the tensor-to-scalar ratio amplitude, r, as well as an improvement on the estimation of the scalar spectral index, ns and its running αs, by the upcoming cosmic microwave background (CMB) polarization experiments that will provide plausible constraints on the quantity Δφ during the horizon exit moment. In addition we discuss the relation between the local variation of the field and the possibilities of an eternal inflation. The results of the analysis are completely model independent
NUMERICAL STUDY OF HYDROGEN MILD COMBUSTION
No full textIn this article a combustor burning hydrogen and air in mild regime is numerically studied by means of computational fluid dynamic simulations. All the numerical results show a good agreement with experimental data. It is seen that the flow configuration is characterized by strong exhaust gas recirculation with high air preheating temperature. As a consequence, the reaction zone is found to be characteristically broad and the temperature and concentrations fields are sufficiently homogeneous and uniform, leading to a strong abatement of nitric oxide emissions. It is also observed that the reduction of thermal gradients is achieved mainly through the extension of combustion in the whole volume of the combustion chamber, so that a flame front no longer exists ("flameless oxidation"). The effect of preheating, further dilution provided by inner recirculation and of radiation model for the present hydrogen/air mild burner are analyzed
Pressure and velocity measurements of an incompressible moderate Reynolds number jet interacting with a tangential flat plate
No full textFlow-induced pressure fluctuations of a moderate Reynolds number jet interacting with a tangential flat plate
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