Non-newtonian fluids

Definition

Non-newtonian fluids are substances that do not follow Newton's law of viscosity, meaning their viscosity can change under different conditions of stress or shear rate. Unlike Newtonian fluids, which have a constant viscosity regardless of the applied force, non-newtonian fluids can behave more complexly, exhibiting properties like shear-thinning or shear-thickening. This unique behavior affects how these fluids transport heat and matter, making them crucial in various applications from industrial processes to biological systems.

5 Must Know Facts For Your Next Test

1. Non-newtonian fluids can be classified into several categories, including shear-thinning (pseudoplastic) and shear-thickening (dilatant), based on how their viscosity changes with applied stress.
2. Common examples of non-newtonian fluids include ketchup (shear-thinning) and cornstarch mixed with water (shear-thickening).
3. The behavior of non-newtonian fluids is often described using models like the Bingham plastic model or the Power Law model.
4. In applications such as food processing, non-newtonian fluids can affect mixing and heat transfer efficiency due to their unique flow properties.
5. Understanding the behavior of non-newtonian fluids is crucial in industries such as cosmetics, pharmaceuticals, and polymer manufacturing, where precise control of flow and mixing is required.

Review Questions

• How does the viscosity of non-newtonian fluids vary with different shear rates, and what implications does this have for their transport properties?
  • Non-newtonian fluids exhibit variable viscosity depending on the shear rate applied to them. For instance, shear-thinning fluids decrease in viscosity with increased shear rate, allowing them to flow more easily under stress. This behavior can significantly influence transport properties such as diffusion rates and thermal conductivity, as the effective movement of particles or heat transfer can be enhanced or hindered based on the fluid's current state.
• Discuss the practical implications of using non-newtonian fluids in industrial processes and how their unique properties affect efficiency.
  • The unique properties of non-newtonian fluids can greatly enhance or hinder efficiency in industrial processes. For example, in food processing, shear-thinning behavior allows for easier pumping and mixing of viscous materials, ensuring uniformity and quality. Conversely, shear-thickening behavior can lead to difficulties in handling and processing materials if not properly managed. Understanding these properties helps engineers design better systems for material handling and energy transfer.
• Evaluate how advancements in understanding non-newtonian fluid dynamics could influence future research in molecular physics and material science.
  • Advancements in understanding non-newtonian fluid dynamics have the potential to greatly influence future research in molecular physics and material science by enabling more precise modeling of complex fluid behaviors. This could lead to the development of new materials with tailored properties for specific applications, enhancing efficiency in various industries such as biotechnology and nanotechnology. Moreover, improved comprehension of these fluids could lead to breakthroughs in energy-efficient transport systems or novel cooling techniques, ultimately contributing to sustainability efforts across multiple fields.

Related terms

Viscosity: A measure of a fluid's resistance to flow, which is constant for Newtonian fluids but variable for non-newtonian fluids.

Shear Rate: The rate at which a fluid is deformed or sheared, affecting the viscosity of non-newtonian fluids.

Thixotropy: A property of certain non-newtonian fluids where they become less viscous over time under constant shear stress, allowing for easier flow.