Reynolds transport theorem

Reynolds transport theorem is a way to understand how things move or change in a fluid, like air or water.

Think of a river flowing downstream. The water molecules in the river are always moving and changing position. If you want to find out how fast the river is flowing, you could measure the speed of one water molecule. But measuring one molecule won't tell you much about the whole river.

Reynolds transport theorem helps us understand the movement of thousands or even millions of water molecules at once. It's like taking a snapshot of the river at a specific moment and figuring out how much water is moving and in what direction.

In order to use this theorem, we need to choose a specific part of the fluid that we want to analyze. This is called a control volume. A control volume is like a fence that we put around a specific area of the river.

Once we have our control volume, we can use the Reynolds transport theorem to look at how much "stuff" is moving in or out of our control volume over time. This "stuff" could be matter like water or gas or even heat or energy.

Overall, Reynolds transport theorem is a way to help us understand how things move and change in large amounts of fluid, and is useful in a variety of fields like engineering and physics.