In this paper we present a 3D computational technique for simulation of complex,
real-world flow problems with fast-rotating mechanical components.  This
technique is based on the Deformable-Spatial-Domain/Stabilized Space-Time
(DSD/SST) formulation, Shear-Slip Mesh Update Method (SSMUM), and an efficient
parallel implementation for distributed-memory parallel computing platforms. The
DSD/SST formulation was developed earlier for flow problems with moving
boundaries and interfaces, including flows with moving mechanical components. 
The DSD/SST formulation requires, as a companion method, an effective mesh update
strategy, especially in complex flow problems.  The SSMUM was developed to meet
the mesh update requirements in simulation of flow problems with fast
translations, and recently, with a new version of SSMUM, fast rotations.  As an
example of the class of challenging simulations that can be carried out by this
technique, we present computation of flow around a helicopter with its rotor in
motion.