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B. Scheid J. Margerit C. S. Iorio L. Joannes M. Heraud P. Queeckers P. C. Dauby P. Colinet 《Experiments in fluids》2012,52(5):1107-1119
The dynamics of thermal ripples at the interface of a volatile pure liquid (C2H5OH) is studied experimentally and numerically. Liquid evaporates under a flow of inert gas (N2) circulating along the interface. The evaporation rate is varied by regulating both the gas flow rate and the gas pressure.
Experiments in microgravity environment allowed to identify a transition to “interfacial turbulence,” along which some particular
events such as nearly periodic and possible intermittent behaviors. Direct numerical simulations have been performed, and
compare qualitatively well with experimental results, offering new insights into the physical mechanisms involved. Small-scale
ripples appear to arise from a secondary instability of large-scale convection cells and their motion seems to follow the
corresponding large-scale surface flow. The relative role of surface tension and buoyancy in triggering these flows is assessed
by comparing experiments and simulations in both microgravity and ground conditions. Qualitative features compare satisfactorily
well such as typical speed and orientation of the thermal ripples, as well as spiral flow in the bulk. 相似文献
12.
Finite element approaches generally do not guarantee exact satisfaction of conservation laws especially when Dirichlet‐type boundary conditions are imposed. This article discusses improvement of the global mass conservation property of quasi‐bubble finite element solutions for the shallow water equations, focusing on implementations of the surface‐elevation boundary conditions. We propose two alternative implementations, which are shown by numerical verification to be effective in improving the smoothness of solutions near the boundary and in reducing the mass conservation error. The improvement of the mass conservation property contributes to augmenting the reliability and robustness of long‐term time integrations. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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Zhabinskii VN Minnaard AJ Wijnberg JB de Groot A 《The Journal of organic chemistry》1996,61(12):4022-4027
The enantiomer of (+)-allohedycaryol, a germacrane alcohol isolated from giant fennel (Ferula communis L.), has been synthesized, thereby elucidating the relative and absolute stereochemistry of the natural product. The synthesis of (-)-allohedycaryol started from (+)-alpha-cyperone (5) which was available in relatively large quantities via alkylation of imine 7 derived from (+)-dihydrocarvone and (R)-(+)-1-phenylethylamine. In a number of steps 5 was converted into the mesylate 4with a regio- and stereoselective epoxidation as the key step. A Marshall fragmentation of 4 was used to prepare the trans,trans-cyclodeca-1,6-diene ring present in allohedycaryol. The conformation of synthetic (-)-allohedycaryol was elucidated via photochemical conversion into a bourbonane system. The synthesis of (-)-allohedycaryol also showed that natural (+)-allohedycaryol has the opposite absolute stereochemistry to that normally found in higher plants. 相似文献