1,721,103 research outputs found
Simulazione delle Grandi Scale (LES) di Flussi Turbolenti in Condotti a Sezione Circolare
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Curvature and velocity strain dependencies of burning speed in a turbulent premixed jet flame
No full textOn the mechanism of diffusion and ionic transport in crystalline insoluble acid salts of tetravalent metals—I Electrical conductance of zirconium bis (monohydrogen ortho-phosphate) monohydrate with a layered structure
No full textThe specific conductance of zirconium phosphate decreases considerably with increase in the degree of crystallinity; however the energy of activation for the conduction apparently does not depend on the degree of crystallinity and is surprisingly low (11–13 KJ/mole). In order to explain these results, different samples of Zr(HPO4)2·H2O of the same degree of crystallinity but having different specific surface area were obtained by sedimentation and the amount of surface counter-ions per cm3 of microcrystals and the specific conductance measured. It was found that a large fraction of the total current was transported by the surface counter-ions, their mobility being ⩾104 times that of the internal ones. Thus, the low activation energy for ionic conduction in the crystalline material is due essentially to the transport of surface counter-ions. These results demonstrate that the counter-ions present at the surface of microcrystals of zirconium phosphate make an important contribution to the total conduction, to the activation energy, and to the electrochemical properties of membranes consisting of microcrystals of zirconium phosphate
Small scale isotropy and universality of axisymmetric jets
Full text linkThis paper addresses the long-standing debate about whether the
asymptotic jet can be universal. It is argued that the ansatz of a
universal spreading rate is inconsistent with more accurate and recent
measurements where the scatter in the opening angle is found to exceed
the experimental accuracy, implying a true lack of universality in these
basic quantities. A universal scaling theory may still be proposed by
including the spreading rate in the similarity transformations. We will
show that this approach leads to a conflict with the presumed recovery
of isotropy in the dissipative scales of the flow. The issue is
addressed here by using direct numerical simulations of free-jets to
finally show that a complete universality is also incompatible with the
experimental data available in the literature. (C) 2007 American
Institute of Physics
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