An efficient scheme is presented for the numerical calculation of hydr
odynamic interactions of many spheres in Stokes flow. The spheres may
have various sizes, and are freely moving or arranged in rigid arrays.
Both the friction and mobility matrix are found from the solution of
a set of coupled equations. The Stokesian dynamics of many spheres and
the friction and mobility tensors of polymers and proteins may be cal
culated accurately at a modest expense of computer memory and time. Th
e transport coefficients of suspensions can be evaluated by use of per
iodic boundary conditions.