Understanding Transport Phenomena of Non-Newtonian Fluids-2 — Lesson 3

This lesson covers the transport phenomena of non-Newtonian fluids, focusing on the measurement of rheology using a capillary viscometer. It delves into the design and working principles of capillary viscometers, explaining how to obtain shear stress and shear rate. The lesson also discusses the potential errors in these measurements, such as end effects, wall slip effects, and deviation from laminar behavior. It provides a detailed explanation of how to correct for these errors, using an example of a 0.5 percent partially hydrolyzed polyacrylamide in water solution. The lesson concludes with a discussion on the importance of wall slip effects in narrow passages and how to quantify and correct for these effects.

Video Highlights

01:14 - Discussion on the working principles and equations required to obtain the shear stress and shear rate.
15:10 - Discussion on the importance of wall slip effect in the case of confined narrow passages and structured materials.
33:57 - Explanation of how to quantify the effect of wall slip on shear rate and make necessary corrections.
58:12 - Explanation of how to identify and correct for deviation from laminar flow in the context of capillary viscometers.

Key Takeaways

• Capillary viscometers are essential tools for measuring the rheology of non-Newtonian fluids.
• The design and working principles of capillary viscometers involve calculating shear stress and shear rate.
• Potential errors in measurements can occur due to factors such as end effects and wall slip effects.
• Correcting for these effects is crucial for obtaining accurate rheological measurements.
• Wall slip effects can significantly impact the flow rate and shear stress of a fluid, especially in narrow passages.