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One of the best illustrations of "Simulating Systems" is this video from the STAR Global Conference 2013, in which Scott D. Reynolds of M/E Engineering explores the use of CFD for studying the impact of wind on the built environment.

Asked to examine the influence of helicopter exhaust plumes  on surrounding bulidings, M/E Engineering decided to simulate the whole system, including fully unsteady wind profiles (with gusts that vary in speed and direction), and the full complexity of the local urban landscape. Best of all, the simulation includes an actual moving helicopter that entrains gas from nearby building plumes as it takes off and lands.

 

"Prediction is very difficult, especially if it's about the future"
 - Niels Bohr, Nobel laureate in Physics

Whether you like it or not, as a simulation engineer you are in the prediction game. Put simply, your job is to predict how an abstract design would perform in the real world, hopefully accounting for the most challenging operating conditions that it would likely experience during its working life.Compared with other professional forecasters such as economists, television meteorologists or political commentators, the audience for engineering predictions is more critical and less likely to forgive. While incorrect weather forecasts are quickly forgotten (at least those that don't involve hurricanes), and one rarely takes economists seriously, the cost of getting an engineering prediction wrong can be enormous.  The failure of a product in service can have serious consequences, particularly in the case of safety critical applications where unforeseen failure can result in injury or loss-of-life. Even in less serious circumstances, the unexpected failure of a product can act to de-motivate consumers, damaging brand reputation, potentially incurring large warranty expenses.

The problem is that uncertainty is a fundamental part of all prediction; no engineering prediction is perfect and no simulation model is a complete representation of the real world scenario. Every model is based upon a set of underlying assumptions that allows it to be solved numerically, but ultimately influences the accuracy of the prediction.  As engineers, we are responsible for acknowledging and understanding the uncertainty in our predictions and, wherever possible, to try and minimize that uncertainty through the application of judicious modeling assumptions.

As a follow up to yesterday's post, here's a presentation from the 2013 STAR Global Conference which took place in Orlando, FL this past March.  Michael Carl of Rowan Williams Davis & Irwin, Inc., shows how STAR-CCM+ was used to evaluate the egress system on a bus deck during a fire. The system was simulated as a whole as well as sectionally, including wind, fire and water from the sprinklers.

We often talk with our customers about their “grand challenges", trying to understand exactly what it is that keeps them up at night thinking: “if I could just _________, that would be a real game changer for my business!” Regardless of which industry they come from, their answers are often quite similar: The majority of these discussions relate to evaluating the performance of an entire system.

Simulating systems often involve dealing with complex physicsAn uncomfortable truth about modern engineering is that there really are no easy problems left to solve. In order to meet the demands of industry, it's no longer good enough to do "a bit of CFD" or "some stress analysis". Complex industrial problems require solutions that span a multitude of physical phenomena, which often can only be solved using simulation techniques that cross several engineering disciplines.

What our customers are really asking for is the ability to "see the big picture". Simulating whole systems rather than just individual components, taking account of all of the factors that are likely to influence to performance of their product in its operational life. In short, to simulate the performance of their design in the context that it will actually be used.

In the past CFD was often described in terms of analogous experimental techniques such as "numerical wind tunnels" and "virtual towing tanks". Although this is a great way of explaining what you do for a living to a stranger at a party, these analogies no longer capture the entirety of the way that engineering simulation is used in industry today. 

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Brigid Blaschak
Communications Specialist
Stephen Ferguson
Communications Manager
Dr Mesh
Meshing Guru
Sabine Goodwin
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Prashanth Shankara
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Joel Davison
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Jean-Claude Ercolanelli
Senior Vice President, Product Management at CD-adapco
Bob Ryan
President Red Cedar Technology