Interviewed at my university with someone from the recruiting team and then was flown in for a day long on site interview during which I interviewed with 4 groups and approximately 12 different people, sometimes individually sometimes as in a group. The questions ranged from technical (e.g. describe how would I solve an operational problem ) to interpersonal (e.g. describe a difficult experience you had working in a group and how did you solve it). The day long interview lasted the entire work day and was tiring but not too difficult. I got offers from all 4 groups so it went well. Having confidence and being genuine seemed to help establish rapport.