  A biconcave particle suspended in a Poiseuille flow is investigated by the
multiple-relaxation-time lattice Boltzmann method with the Galilean-invariant
momentum exchange method. The lateral migration and equilibrium of the particle
are similar to the Segr\'e-Silberberg effect in our numerical simulations.
Surprisingly, two lateral equilibrium positions are observed corresponding to
the releasing positions of the biconcave particle. The upper equilibrium
positions significantly decrease with the growth of the Reynolds number,
whereas the lower ones are almost insensitive to the Reynolds number.
Interestingly, the regular wave accompanied by nonuniform rotation is exhibited
in the lateral movement of the biconcave particle. It can be attributed to that
the biconcave shape in various postures interacts with the parabolic velocity
distribution of the Poiseuille flow. A set of contours illustrate the dynamic
flow field when the biconcave particle has successive postures in a rotating
period.
