  We assume that the individual stars which are located at the peripheral parts
of the spiral galaxies are experiencing a drag force acting upon them radially.
Such a force might be produced by some sort of a dynamically generated viscous
medium, and as the stars are in the state of free fall toward the center of the
galaxy, then it would balance the centripetal force acting on the star, thus
resulting in a terminal velocity. We make no attempt to explain the origin of
the assumed drag force or show how it could be generated, but we have tried to
test such an assumption by fitting the calculated velocity curves of 18 spiral
galaxies with rotation curves obtained from actual observations. Results show
remarkable agreements.
