Chris davidoff // Team First

Chris davidoff // Team First

Our team did a couple different experiments to visualize the flow of smoke or flames.  We attempted to create a fire tornado/spiral by setting two pieces of glass offset, that caused the inrush of air to push the flame into a spiral.  Unfortunately we didn’t get great image results, however I believe this may have been my fault for not trying a higher shutter speed.  I was just shying away from raising the ISO even more, but perhaps it’s worth it for the sake of science!

We also did some work with visualizing smoke (of which we also struggled with for a while until we figured out a good system) — to be read in report.

This resulted in some really cool visuals, here is a video of said actions!

Team 6

  • Chris Davidoff
  • Owen Brown
  • Mathew Davis
  • Casey Munsch

Report

Chris Davidoff, Team 1st, Fall 2018, written 10-9-2018.

This video was created in collaboration with Owen Brown, Mathew Davis, and Casey Munsch

Our team conducted a few experiments in order to visualize a flow of flame and/or smoke.  Our first experiment involving flame did not go well, and I chose not to report on it.  The experiment I am reporting on is this phenomenon of smoke leaving a point source.  I feel we were successful in capturing what we set out to do here.

We were able to capture the laminar sheet flow across a sheer layer until it quickly became turbulent.  The best part about the turbulence is that it started to form very consistent patterns as you can see about half way through the video.  All these actions are caused by the smoke being a buoyant plume.  This is because the smoke is a heated gas which results in it being less dense, thus accelerating upwards.  The sheer layer between the unseen air and the smoke is called Kelvin Helmholtz instability, and is what causes the swirling patterns to appear.  The same instability can be most famously seen on Jupiter, as many of its bands are rotating in opposite directions causing this interaction.

The continuous Kelvin Helmholtz instability can be described mathematically with the Taylor-Goldstein equation.  It is a very complex looking equation, so let’s look more at the onset of instability which is what we are seeing in my video.  This is described by the Richardson number, Ri.

Where g is gravity, p is density, and u is a flow speed.  If Ri is < 0.25 then the layer is typically unstable.

To create this video, we played around with a few different methods of smoke generation.  What we found to work really well, was simply a corrugated cardboard rolled up tightly.  We lit the end of it, let it burn for a few seconds and then blew it out.  This allowed the cardboard to continue to smolder and produce a carbon filled smoke.  Before-hand, we setup a portable projector to act as a bright light source.  Because this light source is so well focused, it created a very clear cut line in which the smoke would appear and then disappear as it entered and left the light.  This focus ability allowed us to keep the entire room from being lit up by having a light source that emitted in all directions.  The camera used was of the following specifications:

  • Nikon D850
  • 55mm f/1.4 prime lens
  • A tripod

The video was shot with the following settings:

  • 120 frames/second
  • f1.4 (wide open)
  • ISO – 2500
  • 1080p

The higher frame rate let us achieve a slow-motion of 4x.  I used a program called Davinci resolve to process the video.  The program let me adjust the color grade as well, so I brought up the contrast and added some purple to the high’s.  The blue in the photo came from the color being emitted from the projector.  I liked the bright contrasting white lines in the smoke, so I blew them out in order to exemplify the vortex’s that were occurring.

In the end I was quite happy with the video we obtained.  It’s a really cool demonstration of the turbulence because of the consistent patterns that show up.  We had sat there simply filming the action for a while and I’m a little sad that we stopped it thinking that we got what we wanted.  What I found after viewing the video is that the best patterns had started to occur towards the end and wished we kept filming for longer.  Regardless, I think it’s a very cool demonstration because of the dual sources of smoke (coming from 1 singular smolder), conducting the same phenomena.  If we acted on this idea in the future, we would set up everything in a more still environment in which other invisible turbulence’s were not occurring.  Even better, would be to chill a fog and pour it over the rising smoke to try and catch both layers sheer with each other.  In our video, we can only see one layer because the air is invisible.

 

Equations were found on Wikipedia: https://en.wikipedia.org/wiki/Kelvin%E2%80%93Helmholtz_instability

Jupiter photo found on NASA: http://photojournal.jpl.nasa.gov/catalog/PIA06502

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21 Comments. Leave new

  • Noah Granigan
    Oct 1, 2018 12:52

    Very cool, this video is well done. The colors, motion and focus of the smoke are all extremely interesting.

    Reply
  • Christopher McFadden
    Oct 1, 2018 12:48

    I love the color choice and the spiraling of the smoke. the music choice is spot on too.

    Reply
  • Peilin Yang
    Oct 1, 2018 12:47

    It’s a graceful video and background music enhances the relaxing sense. The purple vortex is amazing.

    Reply
  • Gregory Collins
    Oct 1, 2018 12:46

    Great color and music choice. It strongly adds to the effect over all. very relaxing vib.

    Reply
  • Chase Cleveland
    Oct 1, 2018 12:46

    This is a beautiful representation of the clip. Great job using colors and music to better display the phenomenon. It has a very peaceful feel.

    Reply
  • Ross Cooper
    Oct 1, 2018 12:46

    This is a pretty amazing video. The focus is perfect, and the colors are vibrant and popping. You can see exactly what the flow is doing, and it’s fantastic in that way.

    Reply
  • Joseph Ryan
    Oct 1, 2018 12:45

    Dreamy is the perfect word to describe this video. The color and music add a lot. It reminds me of laser shows. You can really clearly see all the different typed of spirals the smoke makes as it drifts upwards.

    Reply
  • Anna Lynton
    Oct 1, 2018 12:45

    I love the colors, they really highlight the flow and effect you are going for!!

    Reply
  • Ibrahim Alhajj
    Oct 1, 2018 12:45

    Great work. the video is so cool. I like the editing. the color of the smoke is nice and the song make it so peaceful. Awesome work.

    Reply
  • Michael Karns
    Oct 1, 2018 12:45

    I really like how there are no distractions in this video. You are filming smoke and that is the only thing you see. The music is a nice touch.

    Reply
  • Ivan Komodore
    Oct 1, 2018 12:44

    Great video! The deep colors look great against the black background and the motion is the perfect speed to see the flow well. I also like how the color gradient of the lighting helps to give a sense of three dimensional movement.

    Reply
  • Wenjin Li
    Oct 1, 2018 12:42

    The color looks awesome. I like the contrast and similarity between those two colors. Nice capture on the flow.

    Reply
  • Dylan Crane
    Oct 1, 2018 12:42

    Very cool video of the smoke flow and the colors add a very interesting effect. I think cropping the video could help a little bit but I am a fan of the shot.

    Reply
  • Bradley Busek
    Oct 1, 2018 12:42

    This is a very interesting effect, the lighting is very well done. Great job.

    Reply
  • Brandon Gushlaw
    Oct 1, 2018 12:39

    So cool! The motion-captured shows the spiral at various points. I would say the slightly higher ISO might be better because it generally won’t diminish black background images as bad since the grain won’t be noticeable as much as a white background.

    Reply
  • Garrett Gerchar
    Oct 1, 2018 12:35

    Purple smoke looks so good! Love the spirals you get in the video, it really shows some cool flow. How did you get the smoke to flow so well?

    Reply
  • The swirling of the flame is quite beautiful with the color. I really appreciate the contrast and darkness.

    Reply
  • Hana Kieger
    Oct 1, 2018 12:35

    Really awesome video – the color edits are fun, and you have a great contrast between the bright smoke and the dark background.

    Reply
  • Winston Douglas
    Oct 1, 2018 12:28

    awesome colors on the smoke. the black back drop creates a glowing effect to the smoke and makes it look murky.

    Reply
  • I really like the colors within this video. I wonder if the video would have benefited from some slow motion to really highlight exactly what the smoke was doing. Great job capturing exactly what you were going for though!

    Reply
  • Brent Eckles
    Sep 28, 2018 12:37

    Nice still flame of the smoke. It captures a very distinct moment in time. Like the purple editing to the photo as well as the contrast.

    Reply

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