Incredible non-Newtonian fluid

In a domestic parent-child show, the director of the show group presented a problem for the children: how to use a gum to break open the coconut? I saw the children squeeze the gum into a pointed cone and smashed the coconut into the gum quickly, and the coconut was broken. After seeing this scene, you must think that the show group is a false experiment for the effect of the show. In fact, this is an experiment that uses the properties of non-Newtonian fluids. After reading this article, you will be suddenly bright, and you may even be impatient to do this experiment.
VS Newtonian fluid non-Newtonian fluid
Want to learn non-Newtonian fluid, first we have to know what fluids Yes. A fluid is the form of an object corresponding to a solid. It is a general term for liquids and gases. Its basic characteristics are that it does not have a certain shape and has fluidity. Its flow behavior is determined by viscosity, and the lower the viscosity, the easier it will flow.
According to viscosity characteristics, fluids can be divided into two basic types: Newtonian fluids and non-Newtonian fluids. The viscosity of Newtonian fluid is mainly related to temperature and has nothing to do with the applied pressure. Its viscosity will not change when it is beaten or hit. Most pure liquids such as water and alcohol and light oil are Newtonian fluids. When a non-Newtonian fluid is subjected to a certain force, such as when struck, impacted, or stepped on, its viscosity changes, or the viscosity decreases and it flows more easily, or the viscosity increases and becomes as hard as a solid. Concentrated solutions and suspensions of high molecular polymers are generally non-Newtonian fluids, such as tomato sauce and honey.
Speaking of which, you may still feel a little confused, it is difficult to distinguish the difference between the two. Imagine stepping on the water in the basin with your feet, you will not feel the water suddenly become solid, it is always the gentle water, this is Newtonian fluid. Non-Newtonian fluids change their viscosity or flow behavior when subjected to a certain force. For example, if you mix water and starch in a certain ratio, a non-Newtonian fluid will form. It is a liquid when stirred by hand, but it looks like a solid with a fist! If the entire swimming pool is filled with this non-Newtonian fluid, it may really be able to achieve “water drifting”!
The type of non-Newtonian fluid
non-Newtonian fluid can be divided into time invariant time-varying non-Newtonian fluid and non-Newtonian fluids. The former viscosity is related to the magnitude of applied pressure, the latter is related to the time of applying pressure.
Non-time-varying non-Newtonian fluids are divided into pseudoplastic fluids and expanded plastic fluids.
The viscosity of the pseudoplastic fluid decreases as the applied pressure increases. Like tomato sauce. If you say you want to remove the ketchup from the bottle, you find that it is not easy to pour it out. What would you do then? You will shake or hit the bottle. This will reduce the viscosity of the ketchup and make it easier to flow, so it will be easier to pour out.
The viscosity of the expanded plastic fluid increases as the applied pressure increases. For example, “Europe” is a mixture of corn flour and water, similar to uncooked custard. It was originally a flowing mucus that would become as solid as a solid when suddenly stressed. For example, if you hit it with a hammer, it will not scatter everywhere, but it will become stronger. If you roll it in your hand, it will roll into a hard ball, and once you stop rolling, it will immediately turn into a flowing liquid and slide out from your fingertips. In this case, the viscosity or flow resistance of the substance increases as the applied pressure increases.
Time-varying non-Newtonian fluids can be divided into thixotropic fluids and rheological fluids. For thixotropic fluids, the longer the pressure is applied, the lower the viscosity. Such as honey, constant stirring will make honey more and more smooth. For rheological fluids, the opposite is true, the longer the pressure is applied, the higher the viscosity. For example, cream gets thicker and thicker.
What is the use of understanding non-Newtonian fluids?
By understanding non-Newtonian fluids, we can understand that many seemingly incredible phenomena in life can be explained scientifically. For example, why can chewing gum break coconut? Why the deeper you struggle in the swamp, the deeper you get? Because chewing gum is a non-Newtonian fluid, when it is suddenly stressed, the cone-shaped gum will become as hard as a solid, and it will break open the coconut. The swamp can be regarded as a non-Newtonian fluid.
We can use the properties of non-Newtonian fluids to avoid some problems. For example, we can avoid building houses on certain types of clay. Because earthquakes exert pressure on this clay, it may be that these originally seemingly strong clays have reduced viscosity under pressure and become fluid. If the house is built on this clay, there will be huge hidden dangers. .
At the same time, we can also use the characteristics of this fluid to continuously improve our products. For example, scientists are studying the use of non-Newtonian fluids to make high-performance fillers for use in liquid body armor. Obviously, this new product may better reduce load and increase safety.
Life is not short of beauty, just the eyes that find beauty. Pay attention to interesting phenomena in life, learn to explore and discover, you may be the next scientist.