turn up
With or without an object
Increase the volume, heat or power of something
Could you turn the heating up? It is freezing in here.
Arrive, often unexpectedly (informal)
Half the guests turned up an hour late.
Usage
The 'arrive' sense is especially common in British English; American speakers often say 'show up'.
With or without an object
It can be used with no object, and it can also take one. With an object it is usually separable: turn the volume up, turn it up.
The particle: up
This verb belongs to the group ‘getting bigger, louder or faster’.
Practise it
Add it to your daily practice or see every verb with up.
Further reading: turn up on Wiktionary (CC BY-SA).