In the 21st century.
Aircraft parameters generally fall into two types:
Non-computable parameters and computable parameters.
The former is typically represented by aerodynamic data.
Friends who have participated in aircraft design should know this.
Due to the non-computability of some data, aircraft design often involves observations via wind tunnels.
For instance, tracer particles combined with laser sheet light can qualitatively observe flow field shapes, but it is not precise enough for quantitative flow field analysis.
To truly measure flow fields, PIV technology has developed in recent years.
Which involves using a high-speed camera to capture two consecutive images on the same section.
For the same particle.
There is a time interval between the two images, thus the change in recorded position allows for distance computation of displacement.
Knowing the interval of time between the two images, the particle's velocity can be calculated.
