In general, the more rapidly the blade moves through the vessel, the more shear. Shear is exacerbated by the movement of any agitator through the materials. Particle structures may be torn, broken, or severed and the overall particle size in the mix may decrease. These are called shear forces and can result in damage to individual particles. High Shear: when high viscosity fluids are mixed, stress and friction are created among the particles as they move.Below are some principles of mixing high viscosity materials that should be considered when working with viscous ingredients. For this reason, high viscosity materials are some of the most difficult ingredients to mix effectively and present unique challenges during mixing, particularly byproducts of high shear such as heat and material damage, higher power consumption, and equipment stress and wear. Turbulent flow is directly dependent on the fluid viscosity: the higher the viscosity, the more challenging it is to achieve turbulent flow. When it comes to mixing, turbulent flow is desired within the mixing vessel to create ideal mixing conditions. Some highly viscous materials have a viscosity of hundreds of millions centipoise. For comparison, water has a viscosity of 1 cP while honey has a viscosity ranging from 2,000 to 10,000 cP. Low viscosity materials, such as water, have a lower resistance and flow more rapidly whereas high viscosity materials, such as honey or tar, resist deformation and flow more slowly. Viscosity is a measure of how resistant a fluid is to flow and is measured in centipoise (cP). Viscosity is one of the properties that influences how easily a mixture can achieve homogeneity. Homogeneity of the final blend is a critical aspect of mixing as uniformity impacts the final product in many ways such as stability and durability.
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