Metropolis: My IQ is 300

Chapter 137

The appearance of a girl is naturally disliked by several professors, because the girl itself is a bit strange and impolite, and the speech is very rude, the most important thing is that the hair is still burning.

Several professors around Chen Fan had their eyes drifting. It was obvious that they really didn't want to pay attention to them.

This child is not what they need.

"You say, I'm listening."

"You need me to speak? No reason."

"Do you want to express the smell of cheap perfume on your body? Or is it your fancy dress? Or is it a problem with your mentor?"

‘My mentor is not from Peking University, I got in here. ’

Chen Fan said occasionally, "I remember my enrollment is for many people."

Chen Fan looked at the professor beside him, and several professors turned to each other without speaking.

Chen Fan continued: "Let's continue with the ns equation you mentioned."

The girl nodded and said: "Navier-Stokes equations (English name: Navier-Stokesequations), the equation of motion describing the conservation of momentum of a viscous incompressible fluid. Abbreviated as NS equation. The equation of motion of viscous fluid was first developed by Navier-Stokesequations. It was proposed in 1827 and only considered the flow of incompressible fluids. Poisson proposed the motion equation of compressible fluids in 1831. Saint-Venant in 1845 and Stokes independently proposed the form of a constant viscosity coefficient in 1845, both called Navier -Stokes equation, NS equation for short."

Chen Fan nodded.

"These are basic, what do you tell me?"

"Actually, where is the saying that there is incompressibility, because it is just that the pressure is not enough, but I think, the concept of viscous fluid should not be considered incompressible, because this will be in the derivation, respect and love as new elements Coming in like this is very illogical and, besides, very stupid."

"Uh, your thinking is actually what I need. Your thinking is very interesting to me. The first thing you suspect is the problem of the ns equation itself."

"Yes, if the theory proposed is wrong, then the ns equation is actually another description. I have read many of your documents and some of your documents. I like to read them. Your methods are for the current Under these circumstances, it is completely sufficient to negate this equation."

Chen Fan nodded.

The girl continued: “So, I assumed that the ns equation exists, but what I can’t explain is that incompressible things. I constructed the idea that everything in the world is said to be compressible. Incompressible things are. The ones that don’t exist, there are atoms under the molecules, there are quarks under the atoms, and there are many more under the quarks. These are all spaces, and the technology is not enough. To describe incompressibility, this is like studying a non-existent phenomenon. The focus is still needed. It’s to research. Time is wasted and efforts are not thankful."

Tao Yaoyao said, "Who is your mentor?"

"I'm just a mentor."

"Very unqualified?"

"It's very annoying, I don't like him. He always took my papers out for publication. He might think it was nothing before. This time, I want to try it myself. If Chen Fan is really good, then I’m an idol. It turns out that I guessed right. Chen Fan is different from others."

Tao Yaoyao got up and said, "Well, you guys talk first, I'll go out and take care of something."

When she reached the door, Tao Yaoyao said, "A few professors, do you still want to stay here?"

Several people looked at each other, got up and left the house.

Tao Yaoyao has a lot to deal with.

For the first thing, Hua Xiong found the principal and denied the standards of this review because there is a theory of priority.

After the principal knew about it, he directly eliminated all the lists.

Subsequently, everyone listed a new standard, and the standard for enrollment is national.

People from abroad can also come, but there is so much time. Whoever can come over will come over.

"Isn't this open to enrolling students from all over the world? Even if these students are not selected by Chen Fan, they can still stay in China..."

Hua Xiong said: "Yes, I think the identity of Chen Fan is enough."

Tao Yaoyao said: "I think, regardless of whether it is foreign or domestic, I don't like to treat it differently. I hate the news of a certain school."

The principal said: "That's natural. This time, I am personally responsible. I will see who will make trouble for me. A genius, not necessarily an exam. I have always agreed with this statement."

Perhaps, this is the core, in fact, most of the time, the lack of genius is also the reason for the physique.

Inside the classroom.

Chen Fan discussed with the girl in front of him and reached another level.

"According to Newton's second law, the removal of the control body from the flow field satisfies the following law: at a certain moment, the rate of change of the total momentum of all fluid clusters in the control body over time = the resultant force received by all the fluid clusters in the control body. Control Body forces mainly include surface force and volume force. Surface force acts on the surface of an object, such as pressure and other stresses. Surface force can be decomposed into normal force and tangential force. Normal force is usually pressure, and tangential force is usually viscous force. (Of course this is not absolute, because the normal force also includes the normal stress caused by the compressibility of the flow field); the volume force acts on each fluid cluster in the flow field, such as gravity, electromagnetic force, etc.

Therefore, Newton’s second law can be expressed as: the rate of change of the total momentum of the control body over time = the resultant force of the surface force of the control body + the resultant force of the control body’s volume force (for the convenience of derivation, the volume force is ignored below, and the influence of normal forces such as gravity is more important. When it is large, just add this item).

The above law can be expressed as a mathematical formula using flow field variables:

...

Chen Fan looked at the formula, rubbed his head and said: "Your idea was right at the beginning, but it is still wrong here. I even doubt Newton's second law now, but I have to say that there is a balance in everything in the world. Cyclical argument."

"Yes, I also think so, because no matter how you experiment, there is always some force or energy consumed. Although it is very small, I think these are caused by the irregular movement of the particles themselves."

"Or, watching the universe?"

Chen Fan said: "A molecule is a world? In fact, our world is a huge universe, or man itself is a universe? You read too many novels, right."

"It's not impossible."

Chen Fan picked up the pen and wrote and said: "In theory, with the basic equations including NS equations, plus certain initial conditions and boundary conditions, the fluid flow can be determined. However, due to NS The equation has one more second derivative term than Euler's equation. Therefore, it is difficult to find an exact solution of the equation except under certain conditions.

The simplest case where an exact solution can be obtained is parallel flow. The typical flows in this regard are the Hagen-Poiseuille flow in a circular tube (see tube flow for details) and the Couette flow between two parallel plates (see Newtonian fluid for details).

In many cases, it is not necessary to solve the N-S equation, as long as the order of the N-S equation is analyzed, the characteristics of the solution can be determined, or the approximate solution of the equation can be obtained.

For Reynolds number

In the case of, the acceleration term at the left end of the equation is negligible compared with the viscosity term, so that the approximate solution of Stokes flow can be obtained. RA Millikan [Robert Andrew Millikan] based on this solution gave a famous application (Millikan oil drop experiment), that is, the slow flow of small spherical oil droplets in the air.

For the Reynolds number, the viscous term is negligible compared with the acceleration term. At this time, the viscous effect is limited to the boundary layer near the surface of the object. Outside the boundary layer, the fluid behaves essentially the same as an inviscid fluid, so The flow field can be solved by Euler's equation.

The Bernoulli equation of viscous fluid can be obtained by integrating the N-S equation along the streamline:

Where is the acceleration of gravity; it is the mechanical energy loss caused by the unit mass fluid overcoming resistance and doing work. Therefore, when the fluid flows along the streamline, the mechanical energy is converted into heat energy, which increases the temperature of the fluid. "

Seeing the formulas written by Chen Fan, the girl's eyes were full of suspicion, she suddenly grabbed her hair and tore the paper on the table directly.

"I can't accept it. Anyway, I can't accept this. This is really too Damn it. You are like this, isn't it a dead end?"

Chen Fan said: "Then there is no way, come, come, you say, you say, how to deal with it?"

"I don't know. I refuse to answer this boring question. You are a master of leverage, just like the judicial examination, you have in-depth research and you will never know the answer."

"You look like a classmate of mine, called Zhou Ke."

"I don't know, I am me. By the way, I came to interview in your lab. No, it's your class. It's not. It's yours who wrote the paper. It's not. It's your course."

"Well, you and I will accept it. It's up to you to learn as much as you can. Actually, I don't know how much. I don't have much time. What you study is too slow in my eyes."

The girl smiled helplessly.

You must know that it is the students for the professors to maintain their own strength, because after the students create value, the professors should claim it. This is already an unspoken rule.

And Chen Fan's practice had to make her respect.

"｀ 々My name is Su Xiao, I am a lovely girl."

"Your perfume smells really unpleasant, you should change it, seriously."

"I can dye my hair and remove perfume, don't worry."

"Well, I just don't like to smell it. As for the color of your hair, I don't feel anything. I have actually seen any hair."

The girl smiled happily.

Chen Fan sorted out the files in his hand. He knew that he was about to catch the ns equation soon, but it was still the last step.

In other words, it is the same as the original moonlight conjecture. The last straw, Chen Fan, also needs a beautiful white pigeon to send it to himself.

Let yourself be able to find the final answer.

Before explaining the details of the Navier-Stokes equation, first, a few assumptions must be made about the fluid. The first is that the fluid is continuous. This emphasizes that it does not contain voids that form inside, for example, dissolved gas bubbles, and it does not contain the aggregation of mist-like particles. Another necessary assumption is that all involved fields are all differentiable, such as pressure, velocity, density, temperature, and so on. The equation is derived from the basic principles of conservation of mass, momentum, and energy. In this regard, sometimes a limited arbitrary volume must be considered, called the control volume, on which these principles are easy to apply. This finite volume is recorded as, and its surface is recorded as. The control volume can be fixed in space, or it can move with fluid.

Chen Fan wrote down such a passage, whether it is energy or quality, in fact, these all need to comply with certain laws of physics.

Because in this natural situation, this solution is actually the most correct.

Chen Fan couldn't figure out the last step of the blueprint that the system gave himself.

inspiration?

Chen Fan didn't know, but the previous Chen Fan would be deadheaded, but now, Chen Fan would put down the files and keep thinking, but he would walk and live normally.

"The enrollment matters have been handled almost. During this time, some people will come, but they will be processed according to their academic qualifications."

"I know, it's fine to get stuck."

"Don't you think this is a little differently treated?"

Chen Fan looked at Tao Yaoyao and said, "Actually, if a genius can't handle even the simplest college entrance examination, then there is no need to say what a genius is. I think genius is part of learning ability, hard work. , Is the biggest part, but I think I am a waste, hug."

Tao Yaoyao hugged Chen Fan, Chen Fan closed his eyes.

Tao Yaoyao helped Chen Fan comb her hair and massage her temples.

"Forget it."

"It's okay, you said, does fluid really have to flow?"

"Yes, it doesn't flow, how do you call it fluid?"

"How does it flow?"

"It may be a cycle, you see, many people are cyclic, isn't the water of our earth cyclic?"

Chen Fan froze for a moment, then got up, jumped up, and gave Tao Yaoyao a big mouthful.

Tao Yaoyao stunned Zhan.

"You are really a genius, really, you are the greatest genius, Tao Yaoyao, I know."

Tao Yaoyao now doesn't know if she should be happy or cry, after all, she changed her clothes this time.

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