  In this paper we simulate the cyclic circularly-polarised pulses of the
ultra-cool dwarf TVLM513-46546, observed with the VLA at 4.88 and 8.44 GHz on
May 2006, by using a 3D model of the auroral radio emission from the stellar
magnetosphere. During this epoch, the radio light curves are characterised by
two pulses left-hand polarised at 4.88 GHz, and one doubly-peaked (of opposite
polarisations) pulse at 8.44 GHz. To take into account the possible deviation
from the dipolar symmetry of the stellar magnetic field topology, the model
described in this paper is also able to simulate the auroral radio emission
from a magnetosphere shaped like an offset-dipole. To reproduce the timing and
pattern of the observed pulses, we explored the space of parameters controlling
the auroral beaming pattern and the geometry of the magnetosphere. Through the
analysis of the TVLM513-46546 auroral radio emission, we derive some
indications on the magnetospheric field topology that is able to simultaneously
reproduce the timing and patterns of the auroral pulses measured at 4.88 and
8.44 GHz. Each set of model solutions simulates two auroral pulses (singly or
doubly peaked) per period. To explain the presence of only one 8.44 GHz pulse
per period, we analyse the case of auroral radio emission limited only to a
magnetospheric sector activated by an external body, like the case of the
interaction of Jupiter with its moons.
