By Sierra Castillo, for Get Wet 2016.
Suspended splash, created literally by hand, distorts beautiful mountain background in Phelps Lake in Grand Teton National Park, WY.
Get Wet report
By Sierra Castillo for Flow Visualization, MCEN 4151
Introduction and Background
Flow Visualization is dedicated to producing images and videos of fluid phenomenon. The purpose of the Get Wet image, as our first assignment, is to experiment with different flow phenomena and to get practice producing images of fluids. For my submission, I wanted to demonstrate the physics of water when a splash is induced. Using a GoPro, I swam out into a lake and filmed myself splashing my hand/arms in the water.
Procedure
For this image, there was no technical apparatus used to produce the image. Quite simply, I swam into the lake and began treading water. I positioned my camera close to the water and in line with my body. Once it was positioned as square and level as possible, I swung my arm over my head and into the view of the camera. Once it hit the water, the splash commenced and finished within the span of a few seconds. Later, I went through the video frame by frame, and exported a still image of the splash. It would be impossible to exactly reproduce this image, but capturing a similar one would be fairly simple with a waterproof camera that has video capabilities. A sketch of the positioning of the camera and my arm is shown below in Figures 1 and 2.
Figure 1: Top View of position of my body in the lake.
Figure 2: Front View of position of my body in the lake.
Analysis of Image
Though the process is quite simple, the physics of the image are quite interesting. The image was captured at the end of the splash. If this were a single drop of water, this would be the moment of the Worthington Jet. By this, I mean that the air cavity created when my arm hit the surface of the water was refilled rapidly by water. This in turn, propelled a quantity of water into the air. Due to the surface tension acting on these propelled particles, the sheet of water was created. There is a spot on this sheet that appears to have been hit by a stray particle producing ripples within the sheet. This is an interesting addition to the image and gives some insight into the chaos that commenced after splashing the water. Another interesting aspect of the image is the fingers that form on the edges of the flow.
The camera used to capture the image is the GoPro Hero 4. Unfortunately, the GoPro Hero 4 lineup does not have metadata available, so I can only give information about the settings I changed. The ISO was set to 1600. The white balance was set to 5500K. Finally, the EV compensation was set to 0. The rest of the settings are automatically changed by the camera. The sheet of water is about a foot in length. The distance from the lens to the splash is about 1.5’. The focal length is about 21.9mm for this camera (medium FOV). For post processing, I simply increased the contrast of the image and darkened the shadows a little bit in Photoshop. My intent in these edits was to emphasize the details in the various nooks and crannies in the flow that were lost in the original image. The original image can be seen in Figure 3, below . The edited version can be seen above.
Figure 3: Original, Unedited Still
Conclusion
I like that the image is chaotic and fuzzy in one corner, while the other corner is calm and sharp. The sheet of water is very clear. I like that there is one droplet that bounced off of this sheet and has little ripples in it. It is an interesting “blemish” on the sheet. I also like the various fingers that extend from the sheet of water. Finally, I really enjoyed capturing the image. It isn’t often that a technical engineering course gives you the opportunity to play in the water. It was fun messing around with different splash techniques and going through the footage to see what was actually happening. I wish that I could have captured more of the background so that the distortion of the background has some context. It would have been nice to see the difference between the water-distorted and actual mountain background. I also wish that the lighting was a little better. I think if I had been able to catch the image at a later time in the day when the sun was more behind me, the reflections could have been really interesting. It would also have helped if the clouds weren’t blocking the sun as much as they were. Overall, I am happy with the outcome, especially since it wasn’t a “controlled” experiment so much as it was a test of the spontaneity in the splashing water.
References
Gekle, Stephan, and Jose Manuel Gordillo. “Generation and Breakup of Worthington Jets After Cavity Collapse.” Journal of Fluid Mechanics (2010): 1-3.Research Gate. Web. 27 Sept. 2016.
22 Comments. Leave new
It seems difficult to reproduce this image. The flow is easily seen in the image. The focus is perfect as almost everything in the image is clear and defined.
Amazing that you were able to obtain focus for this image! With the fast motion of water during the creation of a splash, that must have been difficult. The image is slightly dark, a blue sky day could have made for a more bright image.
The splash in this photo is awesome. You can really see all of the fluid elements going on. Crisp, nice photo.
By freezing the motion of the water this image gives me the impression on an ice sculpture. I particularly like the sheet of water on the right side of the image. How cool are the ripples in that one spot on the sheet? That has to be my favorite part of this image as it is unexpected. Instead of the typical gravity waves we are used to seeing in a lake the image captures waves propagating in an elastic membrane where cohesion and surface tension are I’m sure relevant in the establishment of restoring forces. Further right the process by which liquid sheets break up into droplets is visible in action. You have some great physics to discuss here.
Great idea to capture a flow visualization image while vacationing at Grand Teton! I love the outdoorsy feel of this image, it adds a touch of reality to keep the rock and trees in the background. Amazing focus on the splash shows the fine detail of ripples and droplets clearly. Great image!
1. Wonderful artistic energetic action image.
2. The fluid phenomena is clearly illustrated.
3. The photographic technique is excellent and captures the splash well.
Wow, I really like the angle this was shot from. The focus seems good and the contrast is awesome. The timing of it is really good too
I like how the flow takes up the majority of the frame. I am impressed that it is a snapshot form a video captured with a gopro.
This image is very interesting. At a first glance I could not tell what I am looking at, but after taking a longer look the image of a splash is truly depicted. I enjoy the uniqueness of the splash and how a splash is reproducible, but a splash like this would be a bit more difficult to reproduce. Nice use of a natural background and contrast.
Really cool picture! Love how you can see through the glass and how it looks like a film. The droplet hitting the layer is really cool. Just wish picture was bigger!
Really cool. Love seeing the sheets of water breaking on the edges. The focus is really good and it looks great for a gopro. You can barely even tell that it is fish eye.
Good natural background. Great detail of the fluid flow.
Art: The color contrast between the fluid mixing and the background is a little subtle but nice.
Flow: The flow is understandable and easily recognized.
Photographic technique: The focus of the water splashing is great.
1. Really cool image light and color
2. I like looking through the sheets of water
3. I like the setting
Art: Love the background diffraction through the water
Flow: The wavy lens made by the splash
Photography: maybe make it a little brighter. AMAZING WORK!!!!
Well lit photo of splashing water. Very crisp image for a still from a GoPro, well done. In the future maybe crop out the rock to focus more on the fluid flow.
– Great photo, the image is really clear.
– I like the use of the photographic technique using the GoPro.
– It looks like some kind of cool organic squid or something.
-Cool capture, really like the underwater view
-Nice flow visualization of water sheets and their movements
-Shot is very sharp and has a good contrast range
I like the clear water, it is a refreshing change from all the food coloring images that we have been seeing. The way the water goes in all directions is pretty cool. My favorite part is the small circular ripple within one of the ‘sheets’ of water, it is super cool.
A nice image of natural flow visualization. can imagine the river/lake that the splash is coming from. Nice focus on the water where you can see the ripples within.
Amazing capture of the splash without hardly any blur. I like the reference of the rock to the right also. Did you do any post-processing?
I brightened it up a bit and adjusted the contrast, but honestly I have no idea how to do much beyond that. Thanks for the feedback!