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Def: laminar: arranged in layers.
viscosity: the degree to which a fluid resists flow under an applied force.
Colored corn syrup is dropped into a mixture, mixed up, and when the direction is reversed, the drops form their original state.
Filmed at the University of New Mexico - Physics Department.
Explanation: What you watched is "laminar flow", which is a deterministic flow: You can run it, it mixes, and then rewind and it comes back to its original state. This is in opposition to 'turbulent' flow, which is chaotic: you run it and it mixes up, and you run it backwards and it mixes more.
It's all about reversibility. Why does a dropped glass break, but the pieces never unbreak? Why does batter bake into cake, but cakes never dissolve back into batter? It's not because it couldn't; the laws of physics have no dependence on the direction of time: the equations work equally well going from t = 1 to t = 0. The reason is primarily that at t = 1, things are in such a massively changed state that reversing behavior would involve reversing trillions of trillions of particles all with precision. But in the case of this sort of example, the viscous fluid has significantly less molecular motion than water (which is why the drops stay where they are until you start mixing). That means that the minor pulling of the rotating cylinder is fairly regular and orderly, so reversing it's rotation reverses the fluid movement in almost the exact same way that it causes in. In this example, the viscosity of the fluid and design of the mixer (being a cylinder), makes the transition from t = 1 back to t = 0 feasible. You're no longer having to manually reverse trillions of molecules motion.
Colored corn syrup is dropped into a mixture, mixed up, and when the direction is reversed, the drops form their original state.
Filmed at the University of New Mexico - Physics Department.
Explanation: What you watched is "laminar flow", which is a deterministic flow: You can run it, it mixes, and then rewind and it comes back to its original state. This is in opposition to 'turbulent' flow, which is chaotic: you run it and it mixes up, and you run it backwards and it mixes more.
It's all about reversibility. Why does a dropped glass break, but the pieces never unbreak? Why does batter bake into cake, but cakes never dissolve back into batter? It's not because it couldn't; the laws of physics have no dependence on the direction of time: the equations work equally well going from t = 1 to t = 0. The reason is primarily that at t = 1, things are in such a massively changed state that reversing behavior would involve reversing trillions of trillions of particles all with precision. But in the case of this sort of example, the viscous fluid has significantly less molecular motion than water (which is why the drops stay where they are until you start mixing). That means that the minor pulling of the rotating cylinder is fairly regular and orderly, so reversing it's rotation reverses the fluid movement in almost the exact same way that it causes in. In this example, the viscosity of the fluid and design of the mixer (being a cylinder), makes the transition from t = 1 back to t = 0 feasible. You're no longer having to manually reverse trillions of molecules motion.
