Many causes and different for front wheel drive and rear wheel drive cars.
It's hard to say without more detailed information.
a dog
lack of sleep
u joint
Probably you have a bad tie rod (maybe both). You can find it on eBay (around $50.00 L&R). Knocking when turning on front wheel drive is most likely the knuckle on the axle. Look at the rubber boot on the end and I will bet it is split.
wheel bearings?
many many things, Loose lug nuts which lets wheel make knocking noise. Engine will make a knocking noise if it is really low on oil. Some timing belts make a knocking, slapping noise just before they break.These are just a few examples . Have someone ride in car with you as you duplcate the noise and see if they can determine which part of the vehicle it is coming from.
Could be a wheel bearing, better have it checked out soon before the wheel departs from the vehicle.
wheel bearing
Wheel bearings or shock needs replaced at that corner. Unless of course ur missing a cat o_0
Possibly a bad wheel bearing.
I don't know, but I have the same problem with my 2011 Sentra. :(
possibly your wheel bearing is on its way out