Friction Drag on a Cylinder Moving in a Nematic Liquid Crystal

The flow of a liquid crystal around a body depends not only on the geometry of the body but also on the director field around it. For low-Ericksen number flows, the director distribution largely remains in its static equilibrium texture (along a uniform direction far away from the body and, for instance, perpendicular to its surface). We calculate the velocity and pressure of a cylinder in a nematic flow numerically, taking into account topological defects on the particle surface and find the drag force acting on the moving body. The drag force is, in general, non-central, i.e. not aligned with the direction of motion. The lift component of the drag force is a measure for the anisotropy of the system. We show that due to the realistic director texture the drag force is larger than previously thought and the anisotropy, F II / F ^ , smaller and decreasing while approaching the nematic clearing point.