Bibcode
Moreno-Insertis, F.; Schuessler, M.; Ferriz-Mas, A.
Referencia bibliográfica
Astronomy and Astrophysics, v.312, p.317-326
Fecha de publicación:
8
1996
Revista
Número de citas
17
Número de citas referidas
17
Descripción
Accelerated bodies immersed in a fluid experience enhanced inertia due
to the associated co-acceleration of a certain volume of fluid in their
environment. We discuss the concept of enhanced inertia in the framework
of the approximation of thin flux tubes, which is widely used to
describe the dynamics of concentrated magnetic structures in
astrophysical objects. Previous attempts to incorporate this effect have
used a local approach, in which the reaction force of the external
medium on a given tube mass element solely depends on the relative
acceleration of tube and environment at that element. We show that those
previous formulations are inconsistent (either on physical or
geometrical grounds). We present here an alternative derivation of the
enhanced inertia term by geometrical means, still within a local
treatment of the problem but avoiding the pitfalls of previous works.
Our formulation, on the other hand, reveals a basic problem: all local
approaches are bound to give incorrect answers for the reaction force in
as far as they disregard the variation of the external flow in the
direction parallel to the flux tube: in doing so, they generally fail to
provide for global momentum conservation. An exact solution and detailed
analysis for an instance of this failure is given. The discussion of
this paper may be of use also in the hydrodynamical framework of vortex
tube dynamics.