Re: walking in a circle technique??
I agree that you should ask your teacher for a name. He, or one of the senior students at your dojo, would also be a good person to ask about this exercise's purpose and technical details. It's very hard to give useful advice over the internet when we aren't even sure what you're trying to accomplish.
With that said, this sounds like a tenkan exercise to me as well. Except that I don't teach it as "walking uke in a circle. " More like displacing uke so that you can occupy his space.
*If* I've got the right exercise, it's pretty fundamental and can be used to explore lots of different things. You're not going to "master" it in a matter of weeks or even months.