The rheology of thixotropic foodstuffs, which thicken with time and applied shear, is of significant interest in the food processing industry. Understanding the effects of various parameters when mixing these complex foodstuffs is key to controlling the process efficiency and achieving the desired consistency of the final product. Flow modeling can greatly improve your understanding of the mixing process and can help you quickly suggest improvements.

The stirring of yogurt in a cylindrical container is modeled and results are shown below. The rheology of stirred yogurt is described using both a shear-thinning viscosity and a time-dependent, thixotropic effect. The stirring rod, appearing in the 9 o'clock position below, rotates in a circular motion. The initial viscosity was taken at a constant value of 100 Pa·s. The stirring motion leads to a decay in the viscosity of the mixture, which is qualitatively similar to findings reported in the literature.

The figures show the contours of viscosity at 2 seconds (i.e. after 2 turns of the stirrer) and at 10.8 seconds (i.e. after about 11 revolutions of the stirrer), respectively.