Riemann invariants

Riemann invariants are mathematical quantities used in the study of systems of partial differential equations, often found in areas like fluid dynamics and wave propagation. They help describe how certain physical properties, like pressure or velocity, change as waves move through a medium. Essentially, Riemann invariants provide a way to simplify complex equations by identifying conserved quantities along characteristics, which are paths in the space of variables where the system's behavior can be analyzed. This allows for better understanding of the dynamics involved and predictions about how systems evolve over time.