We’ve all been there. We try pouring ketchup onto our fries from the bottle, but it doesn’t come out. So we tap the back of the bottle a few times, and suddenly, the ketchup rushes out and your entire meal is covered with it. Why does the ketchup exhibit such behavior?
The shape of a container can affect the flow of the fluid inside it. Water in a narrow stream flows smoothly, but once the water molecules make their way into a pond, they spread out and no longer flow coherently. If you blow into a long, narrow straw, the air will go straight through. Once the air flows into the large room you are standing in, it slows down as it mixes with the air around it, so someone standing five feet away from you won’t feel a breeze at all.
The above examples show how the shape of a container affect the flow of passive fluids. In today’s study, Kun-Ta Wu and colleagues investigated how the motion of active fluids, fluids that flow using an internal source of energy, is also affected by the shape of their container. They used a system of microtubules, chains of proteins assembled into long, stiff rods. Clusters of a protein called kinesin exert a force on microtubules by “walking” along them. Microtubules interact with each other to form swarms or turbulent-like flows.
Softbites team introduces its official authors. Find here our second post of our series of interviews.