We introduce matrix generalizations of the Navier--Stokes (NS) equation for
fluid flow, and the Kardar--Parisi--Zhang (KPZ) equation for interface growth.
The underlying field, velocity for the NS equation, or the height in the case
of KPZ, is promoted to a matrix that transforms as the adjoint representation
of SU(N). Perturbative expansions simplify in the N→∞ limit,
dominated by planar graphs. We provide the results of a one--loop analysis, but
have not succeeded in finding the full solution of the theory in this limit.Comment: 9 pages, Hard copy figures available from: [email protected]