Drop water into the oil
For the Get Wet first project, we needed to choose an interesting flow phenomenon. There are all kinds of interesting flow visualizations, such as the deformation of a liquid as it drips on a solid surface, the fluctuation of the flame during combustion, I decided to observe the process of mixing two incompatible liquids for the Get Wet project.
For the experiment set-up, I decided to use water and oil to observe. First, I inject a certain amount of water into the container, then put a layer of cooking oil on the surface of the water, and finally inject the clean water into the container. Since the experiment was located indoors, I was unable to provide perfect lighting conditions. I got a better angle by adjusting the position of the container.
Since there is no food coloring in my apartment, the mixing of water and oil is not obvious. In the picture we can see that water and oil are incompatible with each other. That is because the oil is hydrophobic. Water molecules are polar molecules with strong electromagnetic attraction between them. Yet oil molecules are non-polar and have low electromagnetic properties. It makes the oil difficult to diffuse into water, just as nonmagnetic objects are difficult to be adsorbed by magnets.
As is shown in the picture, when water is poured into the oil, a lot of bubbles are created
where the two liquids come into contact. This is because the density of the oil is less than that of water. When the water contact with the oil, the water will sink due to its own weight, and part of the air is carried in the process of water falling in the air. The air is subjected to a larger downward force from the water and a smaller upward force from oil. This is why the bubbles in the picture appear.
I set the ISO of the camera to 3200 and the shutter speed to 1/80. Because of the choice of an improper container, the curvature on the container obscures part of the field of view, affecting the imaging when we observe the pouring of water into the oil. If there is a chance, I will choose a more appropriate container, such as a straight glass.