This Space.com article (April 30, 2018), “Captured! Radio Telescope Records a Rare ‘Glitch’ in a Pulsar’s Pulsing Beat,” notes that:
Pulsars are rapidly rotating neutron stars and sometimes they abruptly increase their rotation rate. This sudden change of spin rate is called a “glitch” …
Approximately 5-6 percent of pulsars are known to glitch. The Vela pulsar is perhaps the most famous – a very southern object that spins about 11.2 times per second and was discovered by scientists in Australia in 1968.
It is 1,000 light-years away, its supernova occurred about 11,000 years ago and roughly once every three years this pulsar suddenly speeds up in rotation.
The full article explores what glitches may be about — that pulsars miss a beat.
Never talked about pulsars in my college fluid dynamics classes.