This question pops up all the time in industry. "How do we solve this problem with a lack of information?" Fortunately enough for me I've seen lots of these questions make it to my desk. In some cases it was a simple as deriving a quantity from the given information that was overlooked. In other cases a mathematical model had to be constructed and the blanks had to be filled in with interpolation and curve fitting. In yet other cases a mock-up of the situation in question was constructed in the laboratory and the operating conditions under scrutiny would be tested. Those are the ways I overcame the lack of information problem.