Conservation Equations of Momentum and Energy — Lesson 6

This lesson covers the concepts of conservation of momentum and energy, focusing on their relevance in high-speed compressible flows. It delves into the integral and differential forms of momentum conservation, the role of shear stress and normal stress, and the impact of velocity gradients and viscosity coefficient. The lesson also discusses the importance of energy equations in high-speed flows, the application of the first law of thermodynamics, and the derivation of energy equations in integral and differential forms. For instance, in high-speed flows of gases, the kinetic energy becomes significant and influences other flow properties, necessitating the use of energy equations.

Video Highlights

01:10 - Recapitulation of shear stress and normal stress.
08:12 - Derivation of the momentum conservation equation in differential form.
14:26 - Discussion on the first law of thermodynamics and its application in deriving the energy equation.
26:54 - Explanation of the integral form of the energy equation.
30:12 - Introduction of the thermodynamic state relation and the equation of state for a perfect gas to solve the unknowns in compressible flows.

Key Takeaways

- Momentum conservation can be understood in both integral and differential forms.
- Shear stress and normal stress play a crucial role in momentum conservation.
- Energy equations are particularly relevant for high-speed compressible flows.
- The first law of thermodynamics is applied to derive the energy conservation equation.
- The energy equation can be expressed in both integral and differential forms.
- In high-speed gas flows, significant kinetic energy can influence other flow properties.