Protected: Pushing the Limits of Physics with High Performance Computing

Pushing the Limits of Physics

Introducing Teton, a High Performance Computing system

By Kelly McSweeney

In aerospace engineering, high performance computing is a critical design and testing tool. Simulations give engineers an enhanced view of air in motion and help to minimize time spent in cumbersome and expensive wind tunnels. But there’s a catch; these simulations require so much computational power that a computer would take far too long to crunch the numbers to make it worthwhile.

That’s why Northrop Grumman’s engineers run their simulations on what they call ”Teton,” a High Performance Computer (HPC) that can process trillions of calculations per second. An excellent example of digital transformation within the aerospace and defense industry, Teton’s cluster of processors work together to solve complex problems, test and validate innovative new designs and perform trillions of calculations per second.

model of plane in wind tunnel

Revealing Invisible Physics with Computational Fluid Dynamics (CFD)

“Each processor solves part of the problem,” says Kristen Gerzina, a senior principal aerodynamics engineer. “At the same time, another processor is solving a different piece of the problem, and then they’re talking to one another.”

Using a technique called Computational Fluid Dynamics (CFD), Northrop Grumman engineers use mathematical equations to run thousands of virtual test flights. These simulations don’t just save time and money — they also reveal the invisible physics that affect the way things fly, such as exactly how air flows over an aircraft’s wing.

This kind of detailed testing helps engineers figure out how aircraft and munition will fly. They can see how design tweaks such as a slight change in the shape of a rocket’s nose will affect drag, lift and propulsion. Every inch of a projectile must be tested and validated for accuracy.

Put simply, Gerzina says, “It’s my job to make sure the things we designed fly pointed end first.”

Once engineers have an optimal design, they run the projectile through simulations of different scenarios, such as different velocities and various angles of attack to see how the air will hit it.

headshot of white woman

Kristen Gerzina

Senior Principal Aerodynamics Engineer

“It’s my job to make sure the things we designed fly pointed end first.”

model of plane in wind tunnel

HPCs Provide Time Savings and Complex Number Crunching

Each simulation can take hours or even days to run, depending on complexity. Having a high performance computing tool like Teton dramatically cuts the time down so engineers can quickly get answers to what they are designing.

“If there are any challenges or problems that come about, especially when we’re pushing new technology, it helps us understand any roadblocks and overcome them in a more efficient manner,” says Gerzina.

To get an even bigger picture, engineers can also combine CFD with another type of simulation called finite element analysis, which is a structural simulation that can show things such as heat transfer and how the prototype will bend or break under different loads. By simulating every aspect of flight, they can troubleshoot problems without wasting time on real-world tests.

“When we couple different tools together, it requires even more computational power for the extra physics,” says Gerzina. “Having something like Teton is great because it has the ability to handle all these different analyses.”

HPCs Cut the Clutter to Get to Physical Tests Faster

Simulations don’t replace physical tests; they complement them. Wind tunnels and full flight tests of prototypes are still an essential step in aerospace design. CFD helps to clear out the clutter by eliminating inferior designs so that the real-world tests only focus on a few of the best possible designs. Plus, the simulations provide valuable data to go along with the physical tests for ultimate testing validation.

A key to using any type of simulation like CFD or FEA for modeling of real world applications is validating those simulations against real world data.  This provides both the user and their customer confidence in the model predictions.

More recently, we’ve begun to look for ways to get extra data from testing, or design specialty tests in order to collect real world data that can be used to tune CFD and FEA simulations that are coupled together.  We’ve partnered with some local institutions to conduct some simpler tests, ones where we get both aerodynamic data and structural data like deflections or pressures. 

Wind tunnel testing, as well as flight testing, are examples of real world data that can be used to independently tune and validate CFD or FEA models. For example, not only are you measuring how much lift you might see on a wing, but you can also measure any kind of wing deflection caused by that lift.

Gerzina’s team has been able to take the results from these simpler but specialty tests to tune and begin validating those coupled CFD-FEA models. Teton helps Gerzina and her colleagues realize the full benefits digital transformation and CFD modeling, especially for advanced designs that push the limits of physics.

Looking ahead for the Northrop Grumman team, Gerzina says, “We’ll continue to look for opportunities to collect real world data to validate models against more complex problems with more coupled physics. We’re always looking for ways to improve and to speed things up and be more efficient.”

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