The image is a stream of corn-starch and water mix (non Newtonian fluid) hitting a table. Take a look at how the stream has hard breaks in areas and smooth flows in others.
Oobleck Drop
Get Wet
Greg Collins
9/30/2018
This is my first image of fluid flow. The focus of this image is the motion and effects of non-Newtonian fluid. More precisely dilatant fluids (aka, corn starch and water). Dilantant fluids are a subset of fluids that as force is applied (shear) the more solid it becomes. In the image there is falling oobleck, corn starch and water, that has regions of solid and liquid depending on the localized stress. This is highlighted in the clean fracturing of the oobleck.
To take the photo a some what runny oobleck must be made. I used one cup corn starch, one cup water and 2 tablespoons beet juice for colorant. Food dye can be used instead but be sure to add two tablespoons of water as well. After the oobleck was made the it was scraped up on a drywall spatula and helped at an angle 8 to 10 inches of the counter surface so the oobleck could flow off. You will observe the oobleck flowing like a viscous fluid on the spatula then become ribbons as it falls off. as demonstrated below.
The shear do to gravitational force acting on the oobleck along the spatula is low enough to allow it to flow easily, but as it flows off the spatula and there is no longer a normal force supporting the weight of the oobleck the shear along the Y axis of the flow increases causing the flow to become solid like. You will observe plastic deformation and finally fracture as the flow falls off the spatula. When the oobleck strikes the table surface, as seen in original post, there will be a brittle fracture do to high shear loads casing the fluid to exhibit greater solid tendencies. Oobleck has this odd behavior do to what is called dilation effect. This means, that in order for the fluid to flow it must expand. It needs to do this because the fluid is just small particles suspended in a fluid, and to flow the particles need to move around each other to do that they must dilatate. If the volume is constrained, this includes surface tension constraints, the particles jam up and cannot flow (Abdoulaye Fall, 2012). This is why you can squeeze oobleck through your hand but if you tray and force your hand in a bowel of it, you feel an almost hard surface instead. this is also why there is a delay in the oobleck from being ribbons when striking the table and then slowly flowing into the puddle that is on the table.
To get the image a white back drop with a neutral surface was used. To can the best contrast a dye is need or the oobleck will blend with the back ground. A black surface and background could be use instead for contrast. Three soft white incandescent lights were used to light the image. White linin towels were used to farther soften the light. For general room lighting halogen track lighting was used.
The image was captured with a mirrorless Panasonic G85 at 16MP, in aperture focus mode. At an F-stop of f/4 and a shutter speed 1/400 s, and iso of 640. The focal length was 16mm. The reason I chose aperture focus was I wanted to control the depth of field. When I went in to automatic mode or shutter mode the camera would focus the depth of field onto the background not the foreground.
The image clearly demonstrates the physics of non-Newtonian fluid, primarily Dilantant fluids. If I did this again I would take the photo with better lighting with a wider depth of field. I felt the photo could be sharper and a lower iso could help with that. I also would pick a more vibrant color as that would be more visually appealing.
References
2, E. B. (2011). Through Thick and Thin. Science, 1230-1231.
Abdoulaye Fall, F. B. (2012). Shear thickening of cornstarch suspensions. Journal of Rheology, 56.
Jaeger, E. B. (2018). A dynamic jamming point for shear thickening suspensions. Chicago: The James Franck Institute, University of Chicago,.
28 Comments. Leave new
I really like how you decided to crop this image. I think that the flow captured here is really intresting, its crazy think to think that something can change from a solid to a liquid so fast.
Great Idea. the physics really show. great work. I think it will look nicer if you added multiple colors
Clear and unique image. Did you have trouble cleaning that up afterwards? The dye you used (which you revealed to be beet juice in class) is not mixed uniformly in some parts of the fluid, which in my opinion makes the image even more interesting, because of the detailed, rich streaks of red that occur, better illustrating that a non-Newtonian fluid can behave as a liquid and a solid simultaneously. You mentioned that your depth of field is more shallow than you’d like it to be – this can be remedied by closing down your aperture (higher f-stop will increase the plane of space perpendicular to the camera that in in sharp focus) and adding more light to your scene to compensate for the decreased amount of light that will hit the sensor due to a smaller aperture.
This reminds me of all those aesthetic/stim blogs on instagram. If you’re not familiar, they make a lot of oddly satisfying videos of people playing with slime and jello. The science of this picture is also interesting, it’s just weird to think of fluids breaking or fracturing like you captured above. There is a little fuzziness in some areas, but it’s not too distracting. I think my biggest complaint would be the cropping. I think it would be better if all we could see is the slime, and completely crop the counter out of the picture.
I really like that you were able to capture both the solid and the liquid states in this image. But the contrast of the goop and the counter makes it kind of flat. Try colorizing or inverting the colors in post.
I really like how this photo is cropped and the shadows that are in it. I think the shadows really help define the fluid motion.
The odd chaotic waves create an interesting flow portrayal. Perhaps a more contrasting background to bring out the pink “goo” would give the image some more depth
It’s really interesting seeing how this came out. The bending and folding of the corn starch seems as though the fluid would stay in this position. If you had given it a darker background I feel like it would make the image “pop” a little more
It illustrates the flow physics phenomena. And nice focus of the stream. But the framing perhaps needs more work.
I really enjoyed the characteristics of both solids and liquids in this picture. The framing is well done, but if the table were less distracting I think it would enhance the image.
Interesting image and flow and good timing capturing the image. I also like you color and cropping choice.
I think this is really cool concept but I would spend a little more time trying to capture this phenomena full on. If you can get a full splash with breakage that might demonstrate it a little better because without knowing what you are trying to capture I would guess this is just some silly putty folded over. Maybe even consider dropping something into the fluid rather than dropping the fluid itself.
The shadows that the fluid is casting accentuate the scale of the motion. The depth of field could be expanded slightly so that everything would be in focus but overall it is clear.
I like the motion of the cornstarch as it hits the ground. The pink color is nice but seems to clash with the tan, grainy ground. Maybe a white background would set some better contrast and leave the focus on the fluid. Good job framing the image as well.
Very cool, it captures the kind of creepiness that the newtonian fluid takes on in brief moments of time. Almost organic (I guess it is organic?) A slow-mo video of this could be really cool too!?
Very interesting color using the beet juice, gives it a very natural coloring. Was there a tripod in use? Did you use a tripod and continuous shooting?
I think that the image really brings out some great contrast in the solid state and liquid motion. The focus is great and it’s a very cool fractured scene.
The texture of the slim looks very smooth and flowing. Maybe next time lay down some tin foil or solid colored surface to eliminate the distraction of the counter top.
I think this is an interesting idea. (Clever with the beet juice!) I do really like the solid and fluid nature of the image – I think you captured the dynamic really clearly. The contrast isn’t super strong between the light pink and the light table, but it’s not too bad. If you were to re-do, I would suggest doing a darker color for the mixture or putting it on a darker table.
I like how you cropped this image. I wonder if you could create more of a contrast between the background and the subject. Perhaps setting up on a darker background would be better.
The cropping of the image looks good. The shape of liquid is pretty good. It shows the dynamic of the liquid.
I think this image is cool and I I liked how you had elements of liquid and solid. I feel like you could have focused in on the point of action a little better, other than that great picture!
The texture of the image is really nice because of the contrast. Also the cropping choice was definitely a good one.
Unique idea, great combination of solid and fluid flow. Editing online is much better than showed in class. Like the vibrant pink color of the goo.
It does a good job of showing the solid and fluid flow. I think it is actually in focus well. As you said, it could be cool to see the fluid in mid air.
The image shows a very cool phenomena. Unfortunately looks like the ISO might be set a bit to high and it seems to come out grainy. The cropped image frames the subject matter very nicely.
I like this photo because it has great feel and texture. The flow of this non Newtonian flow is interesting! I like the color of the goo.
That’s both intriguing and gives me a bit of a queezy feeling. Likely because it’s pink and looks like it could be intestines that have hard breaks in it. Just me? Ok, well I do really like it, it’s a creative idea! I think if you zoomed in more so that you couldn’t see the table and maybe did multiple colors it would have a very artistic look to it!