  In the present work we simulate the basic two-dimensional dynamics of
swarming E. coli bacteria on the surface of a moderately soft agar plate.
Individual bacteria are modelled by self-propelled ridged bodies (agents),
which interact with each other only through inelastic collision and with the
highly viscous environment through damping forces. The motion of single agents
is modelled closely corresponding to the behaviour of swimming bacteria. The
dynamics of the model were adjusted to reproduce the experimental measurements
of swimming E. coli K 12. Accordingly, simulations with loosely packed agents
(p=0) show typical run-and-tumble statistics. In contrast, simulations with
densely packed agents (p=0.3-0.7) are dominated by interactions (collisions)
between agents which lead to the emergence of swarming behaviour. In addition,
we model the motion of single agents on the base of modified run-and-tumble
dynamics, where the bacteria do not turn actively during the tumble. We show
that simulations with densely packed modified agents lead as well the emergence
of swarming behaviour, if rotational diffusion is considered.
