Buoyant plume from a cigar accelerates upward to transition from laminar to turbulent flow.

Buoyant plume from a cigar accelerates upward to transition from laminar to turbulent flow.

By Hunter Miller for Get Wet 2016

This project was a really good experience. I have been known in the past to just watch the end of a piece of incense that was lit and just watch the smoke twirl and curve. I originally wanted to do something with this effect. When trying it with incense the smoke proved to be too thin and not thick enough to show up. What makes more smoke than incense? A cigar. Next I tried a cigar. This one was significantly thicker and had a lot of laminar flow and turbulent flow, which is very interesting. The end of the cigar heats up the air near the tip and then carries particles up that we call smoke. I like how the flow transitions from laminar flow to turbulent in such a short time. This was a very interesting effect. My father helped me set up for the picture with light placements and tin foil reflectors with a black cloth draped behind the cigar. We also experimented with taking the picture with a background of nothing which actually go deeper blacks but there were some more random spots of trees and lights. We ended up using the backdrop but it turned out a little more grey than I would have liked.

Why does this happen? Why does the smoke start laminar and quickly and sharply become so turbulent? This question was asked to the University of Illinois Department of Physics and they didn’t exactly know [1]. They came up with an explanation that most likely makes sense but has not been officially proven yet. The theory is that the warm air takes the smoke particles up at a faster and faster rate. The thing is that the center of the column of smoke is warmer than the rest so it travels up even faster and at a certain point this becomes dominant and the flow becomes turbulent. Happens very quickly and precisely. Just interesting that it is one of those things with a very good theory but no one has proven it to be true.

This photograph demonstrates the relationship between different temperatures of air. Shows how density changes with temperature and the smoke is just a medium to which you can see this motion. It was not easy to capture. We had 16 100-watt fluorescent lightbulbs that were pointing at the cigar and assistance from the flash of the camera. We were holding the cigar with a clamp on a bike stand. I had to do a lot of post processing to get rid of the clamp. Even had to add back into the cigar to make it look normal. The smoke was very difficult to get it to come out nicely. I tried to make the background more black but when I did that it made the smoke look less impressive.

I didn’t only just focus on the smoke. I thought the fact that it was coming from a cigar was interesting and added to the photo. As long as I could remove the clamp successfully I think it would help the photo. As for the settings I had on my camera. ISO was at 500 so that the photo was not too noisy but still made the sensor sensitive enough to see the smoke. The shutter speed was at 1/80th. I wish it was a little faster so that the smoke would’ve been frozen a little better. It still look good but up close you can tell that it isn’t completely crisp. The aperature was as open as it could be so that we got the most light into the photo. The focus is crisp and the depth of field issue didn’t come into effect because it was such a small depth to be able to focus on. I think the photo came out nicely. I have an Idea for another photo that I want to pursue next. Using CO2 from dry ice and letting it fall instead of hot air rising.

This picture captures what I was intending to. I think with time and experimentation I can accomplish an even better image with a brighter flash, More controlled environment. I learned a lot about the physics of warm air flow during this photo and think I have more knowledge on how to improve the picture. Maybe there are things that are better than cigars for making smoke. I want the contrast to be higher and the edges to be sharper. I want the whites to be whiter and the blacks to be blacker. I think that boils down to contrast.

 

 

 

 

 

 

References:

 

“Q & A: Cigar Smoke and Fluid Dynamics.” Physics Van. N.p., n.d. Web. 28 Sept. 2016. [1]

https://van.physics.illinois.edu/qa/listing.php?id=2179

Here you can see cigar smoke as it is carried up by warm air and at first it is laminar and then becomes turbulent.

 

Hunter Miller Get Wet 2016

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22 Comments. Leave new

  • I’m impressed a post about fluid dynamics brings more than 20 comments about arts and aesthetics and no comments at all about fluid dynamics. For starters, the whole argument is wrong: cigarette smoke is a fully laminar thermal convection “flow”. There is no turbulence at all and the only transition we see there goes from stable laminar to unstable laminar.

    Reply
  • This is a very ominous and mysterious image. The cigar almost seems fake and the contrast of the white smoke and the black background is perfect. I always enjoy watching smoke rise and this is a stunning display of its flow.

    Reply
  • Sierra Castillo
    September 23, 2016 10:53 am

    I really like the black and white; the contrast is great and really emphasizes the sharp focus on the smoke. That being said, I would like it if the cigar was more in focus, though this could be a resolution thing from the website. The turbulent flow on the end of the smoke trail is cool.

    Reply
  • Nice smoke photo, clear and crisp. Good representation of the laminar -> turbulent flow transition. Nice photographic technique. I can’t tell if the cigar adds situational clarity or adds too much of a distraction.

    Reply
  • Joseph Straccia
    September 22, 2016 9:40 am

    A nice example of transition in a buoyant plume. The cigar and smoke are effectively isolated from any other distracting elements. The framing is also perfect, starting with the source at the bottom and ending with the mixed out turbulent plume at the top. Transition is a fascinating aspect of fluid dynamics and laminar plumes are interesting to watch because they are fairly sensitive to instabilities. Even in a pretty still room a laminar plume doesn’t last very long before giving way to the non-linear growth of instabilities that cause the plume to transition to turbulence.

    Reply
  • 1. The black and white composition is very effective and artistically enhances the image.
    2. The flow is clearly illustrated and the details are extremely visible.
    3. The photographic technique is nicely done with nice highlights and shadows.

    Reply
  • Schuyler Vandersluis
    September 21, 2016 12:50 pm

    Great contrast! I like how you didn’t crop it- you can clearly see the entire diffusion of the smoke

    Reply
  • Alexander Thompson
    September 21, 2016 12:28 pm

    I love how smooth the smoke looks while it is laminar directly off of the cigar compared to the soft texture when the smoke plume becomes turbulent. Also, great choice leaving the cigar in the image. Although it is not a fluid flow itself, the source of the fluid flow is fascinatingly artistic in this case. Great image!

    Reply
  • I like the black and white settings, and good capture of the full effect of the smoke as it rises. The transition from laminar to turbulent flow is fascinating.

    Reply
  • Really good quality picture! The smoke is so clearly seen all throughout the photo. The smoke patterns are beautiful.

    Reply
  • Zachary Cymanski
    September 21, 2016 12:19 pm

    I like how this image captures the different types of flow with a clean laminar flow going into a turbulent yet non distracting flow. This image has a nice classic feel with the black and white contrast. Don’t know if its possible but maybe brightening the smoke a little more would help make the image “pop” more.

    Reply
  • -Simple yet very elegant image, would make a cool poster
    -Cool to see laminar smoke flow at beginning and then transform into turbulent smoke at the top
    -Good contrast range and like the dark background

    Reply
  • Art: The color contrast between the smoke and the background is really nice with black versus white.
    Flow: The flow is understandable and easily recognized.
    Photographic technique: The sharp focus on the smoke in this piece is great.

    Reply
  • 1. contrast is great
    2. I like the idea of keeping the cigar in the image
    3. gear visualization of the change to turbulent flow

    Reply
  • The contrast between the smoke and background clearly illustrate the flow. Nice analysis of how the flow begins laminar and turns turbulent as it rises. The photo is aesthetic to me in the way that it seems simple.

    Reply
  • Michael Waterhouse
    September 21, 2016 12:18 pm

    Nice use of black and white. No distracting elements. Interesting to see the smoke into two different types of flow (laminar/turbulent).

    Reply
  • I really appreciate that the cigar almost seems floating. It really keeps the user focused on the flow of the smoke. I also like how the photo was framed, unique.

    Reply
  • Alexander Rosenberry
    September 21, 2016 12:18 pm

    The tall image with the still smoking cigar at the bottom gives this a very dramatic and artistic feel. makes me think of a gangster movie or western. The fluid flow is nice as well, and the sharpness of the image makes it nice as well.

    Reply
  • Nice contrast between the black backdrop and the white smoke. Maybe in the future tilt the cigar to hide the label. Well focused image on the smoke, very clear image.

    Reply
  • Maxfield Scrimgeour
    September 21, 2016 12:17 pm

    I like how the cigar is left in the image and the bright white color gives good contrast. Nice work with the background to provide a crisp clean surface for the smoke to be captured on.

    Reply
  • Art: I really enjoy black/white color scheme.
    Flow: Love how it gets more turbulent as it rises.
    Photography: Wonderful lighting. maybe add a little more contrast. Great work.

    Reply
  • – This reminds me of the posters you can purchase at the UMC.
    – There is a strong contrast between the cigar and the fluid flow against the black background.
    – The fluid flow and physics are evident and can reproduce similar images.

    Reply

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