  We use numerical simulation to investigate the effect an intruder's shape has
on the drag and lift forces that it experiences while moving through a granular
medium composed of polydisperse disks of mean diameter d. The intruder
velocity,v, was varied from 0.1 \sqrt(dg) to 20 \sqrt(dg). For frictionless
particles (\mu= 0.0)there is a gradual increase in drag force with increasing
v, whereas for frictional systems (\mu= 0.1,0.5) a constant drag regime appears
at low velocities. The drag force depends weakly on the shape of the object
provided that the cross-section is same. The drag force depends linearly on the
immersion depth, while there is very little variation in lift force with depth
for certain shapes. The lift experienced by the object is a strong function of
its shape at a given velocity. Shape has an effect on the distribution of
contacts around the surface of the intruder which may result in a strong lift
for certain shapes. We also show the force profiles around the intruder
surface.
