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Happy Holidays — Now Let’s Make Snow Sparkle like Diamonds

Light refracting through a snow flake

Nothing says happy holidays like the beautiful sight of snow falling from a bright sky.

Thanks to a refraction simulation created in ANSYS SPEOS, a picturesque snowflake can get you into the holiday spirit any time of the year.

The good news is you can make this simulation yourself.

It uses the same technique used by automotive engineers to test the color of light produced by headlamps.

Read on to learn how it works and how it’s used in industry.

How to Simulate Refraction

Light refracting through a melting snow flake

Mathieu Reigneau, an optical product owner for ANSYS, had fun making the snow refraction simulation.

He simply imported the geometry, applied the properties of water, added sunlight and solved the simulation. From there, Reigneau moved the orientation of the light and geometry until he was satisfied with the rainbow and shine created by the light refracting in the snowflake.

This rainbow and shine are the same phenomena you would see in a diamond. However, you get a lot more rainbows and shine from diamonds. This is because the refractive index of diamonds is almost double the index of ice.

A video of Reigneau looking for the rainbow effect and shine in the snowflake.

“We can recreate the real-life lighting and interpret the snow as objects with the same physical material properties of ice,” says Reigneau. “We then simulate how it captures and refracts the sun’s light and how that is perceived by the human eye.

“The light refracts inside [the snowflake] and bounces multiple times until it finds a way to exit,” adds Reigneau. “Because of the multiple bounces, the light travels a long distance. The light scatters, the rainbow effects accumulate and then it becomes visible. This is how you see color in an otherwise transparent material.”

So why do you see the rainbows in Reigneau’s snowflake when you typically don’t see them in real life?

Reigneau explains it’s because he zoomed in on the snowflake. The sparkle is there in real life, you just need to take a closer look.

The Automotive Applications of Refraction Simulations

Few industries need to simulate how light interacts with a snowflake, but automotive engineers use this technique to ensure that the light coming from headlamps doesn’t scatter into rainbows.

The rainbow effect at the edge of the headlamp’s light makes it hard to read the sign.

“Refraction is the reason why some lights may appear blue around the edges,” says Reigneau. This blue light can cause a few safety concerns on the road.

First, it’s distracting for drivers on long trips. Second, the refracting light makes it harder to read traffic signs.

“By predicting the headlight’s behavior, you can redesign it without needing to build a prototype,” says Reigneau. Skipping the physical prototype means your company has more money for the big bonuses come December.

So, refraction simulations are not just festive — they are also practical. Something to reflect on during the holidays.

To learn about other optical simulations, read up on ANSYS SPEOS.

Until then, happy holidays and happy new year.

Or, as the Vulcans say, “Live long and prosper.”