  A recent study [D. Helbing, A. Johansson and H. Z. Al-Abideen, {\it Phys.
Rev. E} 75, 046109 (2007)] has revealed a "turbulent" state of pedestrian
flows, which is characterized by sudden displacements and causes the falling
and trampling of people. However, turbulent crowd motion is not reproduced well
by current many-particle models due to their insufficient representation of the
local interactions in areas of extreme densities. In this contribution, we
extend the repulsive force term of the social force model to reproduce crowd
turbulence. We perform numerical simulations of pedestrians moving through a
bottleneck area with this new model. The transitions from laminar to
stop-and-go and turbulent flows are observed. The empirical features
characterizing crowd turbulence, such as the structure function and the
probability density function of velocity increments are reproduced well, i.e.
they are well compatible with an analysis of video data during the annual
Muslim pilgrimage.
