Lesson: Shear Force

Overview of this Lesson

This lesson introduces the boundary layer for flow over a flat plate.
The results are relevant to the design of many practice geometries such as gliders, airplane wings, and the hulls of ships.

Benefits of this Lesson

  • Learn how to derive and solve the Navier-Stokes equation (simple case)
  • Learn how to describe the laminar and turbulent boundary layer.
  • Learn how to use correlations to predict shear stress, boundary layer thickness, and shear force for a flat plate.

Goals (Results we intend to create).

  • Learners know main concepts
    • shear stress
    • boundary layer
    • laminar flow (include velocity profile in BL)
    • turbulent flow (include velocity profile in BL)
    • transition
  • Learners can derive Eq. (9.3) and solve this eqn. for Couette flow & Hele-Shaw flow
  • Learners can sketch a boundary layers, id key features and describe
  • Learners can explain pi-groups: delta, cf, Cf, Rex, ReL (see p. 302)
  • Application. Learners can calculate shear stress, shear force, BL thickness, power

Resources (sources of knowledge for reaching goals)

  • Chapter 8

Plan (steps to reach the goals)

1. Goal Setting.
Recommend: Write down personal goals for this lesson. Ask yourself, what do I want? What are my motivations for studying engineering? Make your goals specific (i.e. measurable) and challenging. For more information, see "how to write goals."

2. Derivations
a. Skim pp. 281 to 286.
b. Derive Eq. (9.3).
c. Derive Eqs. (9.4) and (9.5)
d. Derive Eq. (9.6), (9.7a), (9.8), (9.9)

3. Boundary layer
Create a handout with your own sketches and descriptions of the boundary layer. Show the laminar BL, the turbulent BL, and the transition region. Include sketches of the velocity distribution. Label and describe all key features.

4. Calculations: Shear Force, Shear Stress, and Boundary Layer Thickness
a. Make sure you can explain Fig. (9.12) and Table (9.3)
b. Text problems: 9.46, 9.48, 9.56, 9.66, 9.68

5. Lesson Review (Reflective Thinking)
a. Assess your learning using this form. Print1 and staple the form to front of your homework. Resource: (How to write an SII).
b. Assess this lesson using this (form).

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