Momentum Boundary Layer Thickness of Non-Newtonian Fluids — Lesson 2

This lesson covers the transport phenomena of Non-Newtonian fluids, focusing on the momentum boundary layer thickness. It begins with a recap of the previous lecture, discussing the basic aspects of a momentum boundary layer and how the velocity gradient changes. The lesson then delves into the integral momentum equation for boundary layer flows, explaining its validity for both Newtonian and non-Newtonian fluids. The lesson also discusses the integral energy equation for heat transfer in boundary layer flows. The lesson concludes by explaining how to calculate the boundary layer thickness for Newtonian and power law fluids, and how to determine the shear stress in fluid at the surface.

Video Highlights

03:40 - Explanation of the aim of the lecture, which is to find out the momentum boundary layer thickness using the developed equations.
05:30 - Explanation of the velocity profile under certain conditions and the approximation of the velocity profile using a higher degree polynomial.
29:59 - Discussion on the concept of shear thinning fluid and its effect on the boundary layer thickness.
34:22 - Explanation of the calculation of the average shear stress and the drag coefficient for a power law liquid flowing parallel to a flat plate.
37:52 - Discussion on the effect of changing the fluid nature to a Bingham plastic fluid on the boundary layer thickness and the average shear stress.

Key Takeaways

• The integral momentum equation is valid for both Newtonian and non-Newtonian fluids, with the only constraint being that the flow is steady and incompressible.
• The velocity gradient changes from the solid surface to a far away distance when moving in a vertical direction.
• The boundary layer thickness for Newtonian and power law fluids can be calculated using specific equations.
• The shear stress in fluid at the surface can be determined, which is crucial for calculating the drag force and drag coefficient.