A Worthington jet resembling an apple has formed from colored milk being dropped into a pool of differently colored milk.

A Worthington jet resembling an apple has formed from colored milk being dropped into a pool of differently colored milk.

A Worthington jet resembling an apple (manzana) has formed from colored milk being dropped into a pool of differently colored milk.

By Harrison Lien, for Get Wet 2016

 

A Worthington jet is a phenomenon in fluid flow that occurs after a droplet of a fluid hits the surface of another fluid that is relatively deep. Initially, when a droplet hits a surface, it creates a crater in the surface, and then a crown shape is made from the surface fluid around the crater. While the crater is still in shape but as the crown has fallen from its peak height, a Worthington Jet rises from the center of the crater. Different techniques can be used to analyze the fluid flow beyond the general shapes created from a droplet hitting a surface of a deep liquid.

This photograph demonstrates some different techniques that can be applied to the study of such a flow. The photo depicts a Worthington jet produced from colored milk hitting a pool of differently colored milk. Milk was released, one drop at a time, into the pool of milk from a height of 3 feet from the surface. The saucer that was used was 3.97 inches in diameter on the outside of the dish, and a depth of 0.51 inches from the bottom at the center to the top of the rim of the dish, and the inside edges had a gentle curve to them, going from the rim to a flat circle of diameter 0.98 inches at the bottom. The photograph was taken with a Nikon D3300, with a focal length of 200 mm, an aperture of f/5.6, a shutter speed of 1/640 seconds, and an ISO of 400.

The surface was initially milk with intentionally poorly mixed red and yellow food dye at the surface. The milk dropped into the surface was dyed with blue food dye. Several drops had been dropped onto the surface, prior to this photo, as seen by green areas on the surface – including the base of the jet. It can be observed from the droplets that have separated from the jet, that some of the original blue milk from the impact droplet have not mixed with the milk on the surface, and retain their true blue coloration. It is interesting to note the angle at which the jet is escaping, as most Worthington jets go straight up from the surface. This angling could be due to an unintentional initial horizontal droplet velocity. As part of a series of photographs like this one, it can be observed with consistency that the Worthington jets always seemed to lean over in the direction of the side of the dish in which they were closest to; jets formed in the center went straight up, and ones on the sides were bent toward their respective side. This observation introduces a new hypothesis: perhaps the curvature at the bottom of the relatively shallow dish changes the jet direction: more careful testing and photography could lead to an answer.

In the photograph, there is also some motion blur that is visible, and perhaps even a little distracting from the clarity of the photograph. While this decreases from the artistic value of the photograph, a measurement of this motion blur can be used in combination with the shutter speed to determine the average velocity of a flying droplet during that brief instant. Some caution should be used with this technique, because this type of measurement cannot measure jet motion along the axis of the lens of the camera.

Although this photo depicts some techniques that could be used for analysis, there are also some features of this photograph that are less useful for the scientific method and more employed for artistic value. The first example of this would be the coloring: the surface could have been better mixed and pure and free from color contamination of other tests. With this in play, one could use the color mixing of the base of the jet to determine the speed of fluid mixing in the surface as the jet is formed.

With such a high speed photo, some photographic sacrifices needed to be made to produce a quality photo, given the lighting conditions. The apparatus was lit up using a 1200 lumen light, focused at the saucer 2 feet away. Even with this bright light, the photo settings were a little lacking, the shutter speed could have been higher to make the photo crisper. Given the focal length and the size limitations of the lens being used, the aperture was already at its limit, at f/5.6: parts of the surface are a little out of focus, but this is seen as acceptable, considering the flow being showcased is within the focal range, and this depth of field adds a little bit of an artistic aspect to the photo. The next thing that could account for the exposure was the ISO. An ISO of 400 makes this picture clear of grain, and perhaps an exchange of light grain for motion clarity could be a necessary trade-off for artistic merit.

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22 Comments. Leave new

  • Katie Gresh
    Sep 21, 2016 23:13

    1. Artistically well composed and very nice vibrant colors. The white of the bowl is great contrast to the contents.
    2. The flow is clearly illustrated and creative.
    3. The photographic technique is excellent with sharp focus on the focal point of the apple shaped that is formed from the Worthington jet.

    Reply
  • Michael Lloyd
    Sep 21, 2016 12:35

    Good focus to produce a crisp jet, but there is a bit of motion blur on a few of the droplets going out. I like the method you used to get several droplets separating from the jet.

    Reply
  • Preston Marcoux
    Sep 19, 2016 15:57

    It’s hard to distinguish a scale of what is going on, but it is a really cool image with vibrant colors. The impact was captured well and the flow is quickly recognizable.

    Reply
  • Marcus Gurule
    Sep 18, 2016 10:49

    A little bit of motion blur distracts the eyes, overall this is a really great photo. All of the colors are bright and vibrant. Great work!

    Reply
  • Joseph Straccia
    Sep 16, 2016 17:13

    Nice colors and great motion in this piece. Impressive how far the droplets from the jet were flung. I suspect this is due to how shallow the dish was and the energy from the impact not having any place to go other than into rebounding in the jet. Nice true black in the background to isolate the subject. The lighting is great in the image too. A little faster shutter speed would have been the only thing I’d have changed. I like your depth of field and the intensity of the light source was fixed so maybe bumping up the ISO a little would have gotten the exposure time required.

    Reply
  • Maxfield Scrimgeour
    Sep 16, 2016 12:26

    Really like how the bottom bowl appears to be an apple being sucked up out of the bottom of the bowl. The photo could benefit from some sharper focus to really help bring out the droplets.

    Reply
  • Alexander Thompson
    Sep 16, 2016 12:25

    Very cool image, and great observation that the impact of the droplet created a wave that resembles an apple with the Worthington Jets as the stem. Great use of colors to bring out the depth of the jet as well. Your image limits distractions in the background and makes your “apple” the main feature of the image.

    Reply
  • Stephanie Mora
    Sep 16, 2016 12:23

    Artistically, I love the colors used in this. Especially how you can see the loose color mix in the basin. The flow is clearly illustrated, a nice jet with drops shooting off. A little bit of motion blur but still really cool!

    Reply
  • Jeremy Parsons
    Sep 16, 2016 12:22

    Very crisp colors in the image and good contrast. A little bit of motion blur but you indicated your shutter was very fast for the photo. It may be possible that the angle of the jet if pushing the droplet in/out of the page and pulling it out of focus. I think it looks like the top of a bell pepper!

    Reply
  • Mark Noel
    Sep 16, 2016 12:22

    1. The intent was realized in my opinion. Beautiful
    2. A tiny bit of motions blur
    3. The lighting is great. good location

    Reply
  • Daniel Luber
    Sep 16, 2016 12:21

    I appreciate the sharp contrast between the colors and the black back ground. Really keeps your eyes focused on the flow. Also allows you to see the flying droplets very easily

    Reply
  • David Leng
    Sep 16, 2016 12:21

    I like the use of your unique, strong light source. It is interesting to see the flow of the milk across the bowl. The Worthington Jet is is clearly depicted by the green colored milk and the focus is accurate.

    Reply
  • Hunter Miller
    Sep 16, 2016 12:21

    The colors are so vibrant. Like the name a lot. To get a little crisper photo maybe the shutter speed should be a little faster to freeze the droplets a little more. And brighter lights so you can see the colors a little more. Great photo. It totally looks like an apple.

    Reply
  • Brett Sibel
    Sep 16, 2016 12:21

    Art: I really enjoy the many different vibrant colors
    Flow: Unique nonhorizontal dropping
    Photography: The lighting is wonderful

    Reply
  • Sean Harrison
    Sep 16, 2016 12:21

    Excellent dark background, it really helps all the colors in the pool pop. Well done focusing on the jet to get a crisp jet with multiple drops. Interesting that the jet managed to appear like an apple stem.

    Reply
  • Jason Savath
    Sep 16, 2016 12:21

    The worthington jet shoots up extremely high which would make it difficult to reproduce. The color choices are irregular, but it does create an imagery of an apple. Creative piece of art.

    Reply
  • Theo Petrides
    Sep 16, 2016 12:20

    – Cool photo, I like the contrast between the red and green.
    – Looks like a missile hitting the ground and seeing that ripple effect. The additional drops above the jet add nice effect to it.
    – The picture is clean and aren’t that many distracting elements.

    Reply
  • Michael Waterhouse
    Sep 16, 2016 12:20

    Art: Beautiful color. Flow: Details visible. Publishable quality. Photographic technique: Good contrast in color.

    Reply
  • Sierra Castillo
    Sep 16, 2016 12:20

    I really like the bright colors contrasting with the black background and the the white saucer. The focus isn’t perfect. The green jet looks like a separate entity from the red milk, and I think that’s cool.

    Reply
  • Alexander Rosenberry
    Sep 16, 2016 12:20

    Awesome colors, nice and in focus. The ripple surrounding the jet is very appealing, and I like the way that the jet is a different color than the surrounding pool of milk. The outward jet has a little bit of motion blur.

    Reply
  • James Julian
    Sep 16, 2016 12:20

    Art: The color contrast between the background and the colored milk is beautiful.
    Flow: The flow is quickly understandable and recognized.
    Photographic technique: The focus of the milk is great and improves the overall quality of this piece.

    Reply
  • Ryan Daniel
    Sep 16, 2016 12:19

    -Beautiful and vivid colors
    -Captures moment of impact very well
    -Contrast range is good and has great focus

    Reply

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