Stokes' law on non-spherical objects So I have been thinking about Stokes' law and damped harmonic motions in a fluid. Now Stokes' law is only model on spherical objects and if I model this as a spring mass system and oscillate a spherical ball in a fluid then providing the fluid has low viscosity then I would get a dampens harmonic motion. Now If I extend this idea I could use Stokes' law as drag force and use the second order differential from damped motion to find the viscosity of the fluid. 
But what if I change the spherical ball for a say a flat disk (which I see in most text books), how can one model that drag force being created by the  fluid on this disk, and what more what if the disc had holes would we still see a damping effect, if the holes are not uniform or two one side of the plate, could the viscosity of the fluid still be calculated by using non spherical objects?
I am new to fluid mechanics and the reason I ask because in text book I always see flat discs or plates being used but and never spherical object which seems to make the most sense as the fluid flowing around the object would be laminar. 
 A: 
But what if I change the spherical ball for a say a flat disk (which I
  see in most text books), how can one model that drag force being
  created by the fluid on this disk, and what more what if the disc had
  holes would we still see a damping effect, if the holes are not
  uniform or two one side of the plate, could the viscosity of the fluid
  still be calculated by using non spherical objects?

In the case of a non-spherical object, Stokes' law can no longer be used to predict the drag force.
Instead the drag equation is used:
$$F_D=\frac12 \rho v^2 C_DA$$
Where $F_D$ is the drag force, which is by definition the force component in the direction of the flow velocity,
$\rho$ is the mass density of the fluid,
$v$ is the flow velocity relative to the object,
$A$ is the reference area, and
$C_D$ is the drag coefficient – a dimensionless coefficient related to the object's geometry and taking into account both skin friction and form drag, in general $C_D$ depends on the Reynolds number.
As a result, the linear second order differential equation (the equation of motion) used to calculate the case of a perfect sphere now becomes a non-linear second order differential equation of the type:
$$\ddot{y}+a\dot{y}^2+by=0$$
This is mathematically much more demanding than the linear case (and is not the EoM of a damped harmonic oscillation).
Note also the the factor $C_D$ is dependent on $R_e$, thus dependent on $v$.
