Non-newtonian fluid

Definition

A non-newtonian fluid is a type of fluid whose viscosity changes with the applied shear rate or stress, meaning it does not have a constant viscosity. Unlike Newtonian fluids, which maintain a consistent flow regardless of the forces acting on them, non-newtonian fluids exhibit unique behavior such as shear thinning, shear thickening, or even time-dependent viscosity. These characteristics make them fascinating and complex in their interactions with external forces.

5 Must Know Facts For Your Next Test

1. Non-newtonian fluids can behave in ways that are counterintuitive; for example, they can become thicker when stirred quickly (shear thickening) or thinner when stirred slowly (shear thinning).
2. Common examples of non-newtonian fluids include cornstarch mixed with water (oobleck), ketchup, and paint, each exhibiting different flow behaviors under stress.
3. The behavior of non-newtonian fluids is important in many industries, such as food processing, cosmetics, and pharmaceuticals, where precise control over viscosity is crucial.
4. These fluids can be classified into categories based on their response to shear stress, including Bingham plastics, thixotropic materials, and dilatant materials.
5. Understanding non-newtonian fluid dynamics is vital in applications like blood flow in the human body, where blood exhibits non-newtonian properties affecting circulation.

Review Questions

• How do non-newtonian fluids differ from Newtonian fluids in terms of viscosity and flow behavior?
  • Non-newtonian fluids differ from Newtonian fluids primarily in that their viscosity is not constant and changes with the shear rate or stress applied. While Newtonian fluids maintain a consistent viscosity regardless of the flow conditions, non-newtonian fluids may become either thicker or thinner depending on how fast they are stirred or how much force is applied. This unique behavior makes non-newtonian fluids complex and requires different considerations for analysis and application.
• What are some practical applications of non-newtonian fluids in various industries, and why is understanding their behavior important?
  • Non-newtonian fluids find applications across multiple industries including food processing (e.g., sauces and dressings), cosmetics (e.g., creams and gels), and pharmaceuticals (e.g., ointments). Understanding their behavior is crucial because it affects how these products are manufactured, packaged, and used. For example, knowing how a paint behaves under shear stress can influence its application method and the final finish on surfaces.
• Evaluate the significance of studying non-newtonian fluid behavior in relation to real-world phenomena such as blood flow or the behavior of certain materials under stress.
  • Studying non-newtonian fluid behavior is significant because it helps us understand complex real-world phenomena like blood flow, where blood's varying viscosity impacts circulation efficiency and health outcomes. Similarly, evaluating how materials like oobleck behave under stress provides insights into engineering applications where materials must withstand varying forces. By analyzing these behaviors, we can improve product formulations and design better systems for both industrial processes and medical treatments.

Related terms

Viscosity: A measure of a fluid's resistance to flow or deformation, often described as the 'thickness' or 'stickiness' of a fluid.

Shear Stress: The force per unit area applied parallel to the surface of a material, often leading to deformation in fluids.

Rheology: The study of the flow and deformation of matter, particularly focusing on the behavior of complex fluids under various conditions.