Exa Corporation Physics Validation Engineer interview questions

Applied online. Had a call from the HR manager about availability details and some behavioral questions. Within a couple of days, got a call from the Hiring Manager. The phone interview lasted an hour with technical questions, and was encouraged to complete the unanswered and partially answered questions through email. Later invited onsite at HQ (Burlington, MA) for a day long interview starting with an hour long presentation about PhD research work. The day long process involved meeting at least 6 different people from the Physics R&D including Physicists, Mathematicians and senior researchers with engineering and software background.