system
Given the following post, respond as if you're commenting on Reddit:
human
Could someone please attempt to explain entropy to me in a fluid dynamics context?

I have recently started a job as an aerothermal engineer and have had trouble understanding exactly what entropy is in a physical sense. I've encountered it in a few cases, for example, viewing entropy plots to locate pressure shocks over aerofoils, but I can't grasp exactly what it is.
gpt
Entropy (both in computer science and physics) is a measure of the number of possible states of a system.

Creating entropy somewhere means you have taken a certain path in reality, out of a great number of others. The greater the entropy increase, the greater the number of possible states your system can have. The sheer number of these new potential other states basically makes it impossible to go back to a point where the number of states were comparatively hugely smaller. Creating entropy means there is no going back in time.

Entropy can also be seen as a measure of disorder: the more the possible states of a system, the more you'll see random behavior appear.

When your fluid is laminar, little entropy is being created: your fluid has a very low number of ways to evolve. When your fluid is not laminar, when there are pressure shocks, a great number of possible states are being created. And you're likely to see turbulences.

When plotting entropy, you are basically viewing where the action takes place (where a single reality is chosen over a great number of potential states).