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Simulation data management: A little or a lot

At Tecplot, Inc., we’ve had many conversations with our engineering customers about how they use CFD in their day-to-day work. From these conversations, we’ve found that CFD engineers fall into two groups: Exploratory CFD and Production CFD. Both groups can benefit from a robust simulation data management software tool. By listening to customer needs, Tecplot, Inc. has been able to meet the needs of both groups with Tecplot Chorus, which lets engineers quickly spot trends and anomalies in hundreds or even thousands of cases. Then they can quickly dive into the underlying fluid dynamic phenomena.

Simulation Data Management for Exploratory CFD

Most engineers these days are using simulations in what we call exploratory CFD. With a particular question in mind, they start by figuring out the correct initial set of conditions, and the correct solver to arrive at the best possible answer.

This way of working is usually an attempt to solve one very precise operating condition, such as a high lift environment for a 787. Under those conditions an engineer might be trying to optimize the solution, so they will fine-tune things like solver or mesh. They’ll ask questions like, is it first order upwind? Or is it second order upwind? Or should they go for an even higher order? What thermodynamic models should they use? Tweaking the available knobs that they have around their simulation – to get the highest and most accurate simulation they can – is what we’re calling exploratory CFD.

Over the last five years the way engineers do exploratory CFD has changed dramatically. For instance we used to have limitations in grid size, now we see engineers running grid sizes of 1 billion to 2 billion cell models. This simply makes it easier for engineers to test things. An engineer can run four different simulations to get to the best possible solution.

Simulation Data Management for Production CFD

When we refer to production-level, high-fidelity simulation, we’re talking about situations when engineers are looking at a wide set of operating conditions. Usually, these engineers start out working on the problem in exploratory CFD to narrow in on a mesh and good solver conditions. Then the engineer will apply that knowledge to a whole spectrum of solutions in order to, for instance, predict the performance of a vehicle in an attempt to optimize its geometry.

In these situations, an engineer might be looking at a bunch of different iterations to figure out how a wing design might behave in its entire flight envelope, for instance. This kind of work generates a huge number of simulations.

In one of our blog talk radio shows we spoke about the advent of the petaflop and how greater computational power is changing the working methods of engineers using CFD. It’s very logical that increasing computing power will help those engineers working in production oriented CFD; but what about those engineers working in exploratory CFD?

To answer that question, Dr. Durrell Rittenberg of Tecplot, Inc. recounted dealing with simulation data management from his graduate school days. “Back when I was a grad student, I used to run this particular code, which took about a week to run. Knowing that it would take a week meant that I had to really think through whether or not I had the best set of conditions, because ultimately I couldn’t afford the time or the money to run through too many of these. Typically I would only run one or two because if I made an error, it was just too costly.”

Engineers’ comfort in running larger CFD runs has increased dramatically since more computational resources became available. Now they run that same set of simulations in just 30 minutes. The fact that engineers can do so much more in so much less time means they can now explore even more. For instance, they can change the thermodynamic model. They can explore a higher order solution.

Many companies that we talk to want to be able to set up a large experiment at night and then come back in the morning and have it waiting for them.
So, now, engineers working in exploratory CFD don’t have the pain associated with making a small mistake. They can come back and run many different methods and ways of getting more information from their experiment.

At Tecplot, Inc., we’re happy to help engineers working in exploratory or production CFD. Ongoing improvements in our software will help them arrive at better engineering solutions faster. We’re doing constant upgrades to Tecplot Chorus, as well as our other products, all to make the engineer’s job easy and more intuitive.