Variational principles for topological barotropic fluid dynamics     

Asher Yahalom  Donald Lynden-Bell 《地球物理与天体物理流体动力学》2014,108(6):667-685

Barotropic fluid flows with the same circulation structure as steady flows generically have comoving physical surfaces on which the vortex lines lie. These become Bernoullian surfaces when the flow is steady. When these surfaces are nested (vortex line foliation) with the topology of cylinders, toroids or a combination of both, we show how a Clebsch representation of the flow velocity can be introduced. This is then used to reduce the number of functions to be varied in the variational principles for such flows. We introduce a three function variational formalism for steady and non-steady barotropic flows.  相似文献   

The Human Orrery: Ground-based astronomy for all     

Mark Bailey    David Asher Astronomers  Apostolos Christou Astronomers 《Astronomy& Geophysics》2005,46(3):3.31-3.35

Mark Bailey, David Asher and Apostolos Christou describe an interactive, open-air model for explaining the motions of the planets and the position of the Earth in space, which was formally opened at the Armagh Observatory on 26 November 2004.  相似文献