A method and an article of manufacture for determining a rate of change of orientation of a plurality of fibers disposed in a fluid are provided. The method includes determining a first tensor indicative of the rate of change of orientation of the plurality of fibers in the fluid in a predetermined region due to rigid body rotation of the plurality of fibers and the fluid. The method further includes determining a second tensor indicative of the rate of change or orientation of the plurality of fibers in the fluid in the predetermined region due to deformation of the plurality of fibers and the fluid in the predetermined region, utilizing a first scalar value that reduces the rate of change of orientation of the plurality of fibers due to deformation of the plurality of fibers and the fluid. The method further includes determining a third tensor indicative of a total rate of change of orientation of the plurality of fibers based on the first and second tensors, wherein the third tensor is an objective tensor.