Transient flow (Reynolds no. 896) of non-Newtonian CM cellulose aq. soln. (concn. 0.28%) in a Rushton turbine-stirred vessel was computer-simulated. Contours of flow velocity and mol. viscosity were established for varying turbulence (wall functions, enhanced wall treatment, Launder-Sharma model). A good agreement of the calcd. and exptl. data was achieved only close to vessel wall (10-20 mm) but large differences were obsd. inside the vessel.