1. Lagrangian and Eulerian Frames of Reference

Eulerian Frame

Label points in space with a coordinate system that is either fixed or moving in a prescribed way

Lagrangian Frame

Each ‘particle’ in the system is labelled, and the label is fixed to the ‘particle’ as it travels around the system

2. Control Volumes

Conservations Laws

• Heat Transport deals with exchange of Thermal Energy between systems
• Energy can neither be created nor destroyed(only changes forms)
• Conservation Laws can be written in terms of rates

<aside> 💡 Rate of Change of U = Rate of Inflow - Rate of Outflow + Rate of Generation

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$$ \frac{dU}{dt}= \frac{\delta Q}{\delta t} - \frac{\delta W}{\delta t} + \frac{\delta S}{\delta t} = \dot{Q} - \dot{W} + \dot{S} $$

There are many different forms of $U$:

• Thermal Energy, arising from molecular motion
• Latent Heat, arising from intermolecular forces
  • important to phase changes
• Chemical Bond Energy
• Nuclear Binding Energy

Control Volume Definitions