1,478 research outputs found
Blob formation and acceleration in the solar wind: role of converging flows and viscosity
The effect of viscosity and of converging flows on the formation of blobs in
the slow solar wind is analysed by means of resistive MHD simulations. The
regions above coronal streamers where blobs are formed (Sheeley et al., 1997)
are simulated using a model previously proposed by Einaudi et al. (1999). The
result of our investigation is twofold. First, we demonstrate a new mechanism
for enhanced momentum transfer between a forming blob and the fast solar wind
surrounding it. The effect is caused by the longer range of the electric field
caused by the tearing instability forming the blob. The electric field reaches
into the fast solar wind and interacts with it, causing a viscous drag that is
global in nature rather than local across fluid layers as it is the case in
normal uncharged fluids (like water). Second, the presence of a magnetic cusp
at the tip of a coronal helmet streamer causes a converging of the flows on the
two sides of the streamer and a direct push of the forming island by the fast
solar wind, resulting in a more efficient momentum exchange
Notes on divisible MV-algebras
In these notes we study the class of divisible MV-algebras inside the
algebraic hierarchy of MV-algebras with product. We connect divisible
MV-algebras with -vector lattices, we present the divisible hull as
a categorical adjunction and we prove a duality between finitely presented
algebras and rational polyhedra
Achieving Fast Reconnection in Resistive MHD Models via Turbulent Means
Astrophysical fluids are generally turbulent and this preexisting turbulence
must be taken into account for the models of magnetic reconnection which are
attepmted to be applied to astrophysical, solar or heliospheric environments.
In addition, reconnection itself induces turbulence which provides an important
feedback on the reconnection process. In this paper we discuss both theoretical
model and numerical evidence that magnetic reconnection gets fast in the
approximation of resistive MHD. We consider the relation between the Lazarian &
Vishniac turbulent reconnection theory and Lapenta's numerical experiments
testifying of the spontaneous onset of turbulent reconnection in systems which
are initially laminar.Comment: submitted to Nonlinear Processes in Geophysic
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