  The swimming properties of an E. coli-type model bacterium are investigated
by mesoscale hy- drodynamic simulations, combining molecular dynamics
simulations of the bacterium with the multiparticle particle collision dynamics
method for the embedding fluid. The bacterium is com- posed of a
spherocylindrical body with attached helical flagella, built up from discrete
particles for an efficient coupling with the fluid. We measure the hydrodynamic
friction coefficients of the bacterium and find quantitative agreement with
experimental results of swimming E. coli. The flow field of the bacterium shows
a force-dipole-like pattern in the swimming plane and two vor- tices
perpendicular to its swimming direction arising from counterrotation of the
cell body and the flagella. By comparison with the flow field of a force dipole
and rotlet dipole, we extract the force- dipole and rotlet-dipole strengths for
the bacterium and find that counterrotation of the cell body and the flagella
is essential for describing the near-field hydrodynamics of the bacterium.
