Recently I got a chance to be in a room with a bunch of Ph.D. students and faculties of the mechanical engineering department. Faculties were presenting their research to other faculties and Ph.D. students. I quickly found that regardless he/she is an experimentalist, a theorist, or a numerical guy (like me), there’s always some slides showing the results from numerical simulations (or some people prefer to call them computer simulations). And at the end of the event, there was a 30-minute slot for all scholars to discuss anything they like. No one raised any question, it was quiet. So I decided to throw a question to ignite some discussion: how confident are you with your computer simulations?
I raised this question because I am not confident with any numerical simulation result I produce. Don’t get me wrong. I’m not attacking computer simulations, and I am a pure numerical guy. I was a simulation engineer in the industry in the past and a Ph.D. student in numerical methods now in the academia. But I always have this question in my mind because of a past event.
A long time ago before I came back to academia, I was a simulation engineer in the manufacturing industry. I used my skill to provide suggestions to customers regarding these or those kinds of problems during the manufacturing processes. There was once a customer came to me and hoped me to do simulations for them regarding a problematic mold they have. Usually a case like this, computer simulation is just a tool to help us design solutions, and we always need to do some experiment-based tests to confirm the solutions.
But this case was urgent. No time for the customer to do more careful examinations and tests. So they would modify their mold merely based on my simulations. They told me the modification would cost them one million dollars, and they only had one shot. So they wanted me to make sure the simulation results were correct. And when I heard that the modification would cost one million, I freaked out. I just couldn’t guarantee them that the simulations are accurate enough. I was not confident enough because as an expert in numerical simulation, I know how many uncertainties and errors are involved in simulations. So I just couldn’t tell them: yes, just trust the simulations and go ahead with the modification.
Ever since then, whenever I see someone showing their results of computer simulations, I always want to ask if they are confident with his/her simulations if one million will be spent merely based on his/her simulations results without further experiment-based tests.