In this work, a tool for calculating viscoelastic flows with rotating geometries in OpenFOAM based on the finite-volume method is presented. The tool combines the split-stress tensor approach and viscoelastic differential constitutive equations with the sliding-mesh technique. With this tool, a CFD simulation was run for a geometry of a spherical stirrer in an aqueous solution of carboxyl cellulose. Additionally, a rheological characterisation of that solution was conducted. For validation, the simulations were compared with flow field data acquired through particle image velocimetry measurements.