  We present a numerical model in which a cold pair plasma is ejected with
relativistic speed through a polar cap region and flows almost radially outside
the light cylinder. Stationary axisymmetric structures of electromagnetic
fields and plasma flows are self-consistently calculated. In our model, motions
of positively and negatively charged particles are assumed to be determined by
electromagnetic forces and inertial terms, without pair creation and
annihilation or radiation loss. The global electromagnetic fields are
calculated by the Maxwell's equations for the plasma density and velocity,
without using ideal MHD condition. Numerical result demonstrates the
acceleration and deceleration of plasma due to parallel component of the
electric fields. Numerical model is successfully constructed for weak magnetic
fields or highly relativistic fluid velocity, i.e, kinetic energy dominated
outflow. It is found that appropriate choices of boundary conditions and plasma
injection model at the polar cap should be explored in order to extend present
method to more realistic pulsar magnetosphere, in which the Poynting flux is
dominated.
