Section 230

This problem can be said to be the key difficulty in proving the NS equation.

Xiao Yi began to deduce the process of the explosion solution on the draft paper.

[{[u/t+(u)u=p+νΔu], [u=0]……]

[lim(t→T)∥u(,t)∥Hk=∞]

At a certain point in time, the speed becomes infinite.

In a physical sense, it means that at a certain moment, the speed or energy density of the fluid becomes infinite.

It is as if the originally calm water in the pond suddenly exploded violently, and even use your imagination to turn the grenade into a water grenade, shake it vigorously before throwing the water grenade, so that the fluid inside it becomes turbulent enough, and then throw it out, and finally throw it to the enemy's side, and explode directly, causing power that may even be stronger than that of a grenade.

It can even explain the principle of the ability of those who have mastered superpowers related to water, that is, they can control the fluid force in the water and accurately control it to reach the "explosion solution" condition at a certain moment.

But obviously, this is a completely impossible thing.

This problem has been discussed in academia for many years, but people have never had a good way to explain the conditions for the formation of explosive solutions.

"For now, some related mechanisms have been discovered, um... one is called energy cascade and turbulence, which means that in turbulence, energy is transferred from large scale to small scale, which may cause the speed or velocity gradient on the small scale to become very large, and eventually lead to explosion."

This is easy to understand, because of the conservation of energy, the original one cubic meter of fluid energy is condensed into one cubic millimeter, which naturally leads to a sharp increase in the fluid energy within this cubic millimeter, and then an explosion occurs.

"In addition, the influence of initial conditions, such as some highly concentrated and strongly rotating initial flow fields may produce explosive solutions."

"Therefore, finding a good initial condition is the key to proving the NS equation."

"Initial conditions... initial conditions..."

Xiao Yi entered into deep thinking.

Until the end, he stood up suddenly.

"Need data!"

Since we want to find the appropriate initial conditions, there is a simple method, which is to set various initial conditions, and then use numerical simulation methods to determine the subsequent impact of different initial conditions on the fluid, such as when the explosive solution will appear, and the change of its data in the period before the explosive solution occurs.

And this requires the help of computers.

He went to the computer room, set up the model, and started running it on the server in the laboratory.

But at this time, a problem occurred.

The computing power of the laboratory server is not enough!

Looking at the slowly moving progress bar, his expression darkened.

Wang Hao, who was next to him, was also stunned when he saw this scene, and said: "Our server is worth 10 million, professor, what are you calculating?"

Xiao Yi pulled the corner of his mouth and said: "Some direct numerical simulation models of NS equations."

"Oh, that's not surprising."

Wang Hao nodded.

The direct numerical simulation of the NS equation is one of the models with the highest computing power requirements. Moreover, Xiao Yi has to calculate not only one model, but hundreds of models, covering various situations of fluid operation, such as pipe flow, boundary layer flow, open channel flow, etc., which require even higher computing power.

"Remember, when the laboratory is expanded next time, the computer room should also be expanded. By the way, ask how much it costs to build a supercomputing center and what is the scale of 100 million."

Xiao Yi waved his hand and prepared to build a supercomputing center for their laboratory.

No way, there is a lot of money, so you can be willful!

Wang Hao next to him swallowed his saliva.

Good guy, 100 million, it seems that their laboratory is really rich.

"Yes, professor!"

...

It is not convenient to do it here in the laboratory. After all, the laboratory server is not only used by him, but also by others sometimes. He is not so dictatorial.

This time, the amount of data must be used by supercomputing.

It just so happens that there is a supercomputing center in Fei City that has been established in recent years. The name is also very nice, called Chaohu Mingyue.

It seems that I can go and have a look.

…

The Chaohu Mingyue Supercomputing Center is located in the Fei City High-tech Zone. Its name naturally comes from a famous lake in Anhui Province - Chaohu Lake.

"Professor Xiao, I have heard of you for a long time!"

Director Tu Ran of the Chaohu Mingyue Supercomputing Center stood at the door. When he saw a group of people coming, he smiled and greeted the leader.

That person was naturally Xiao Yi. After confirming that he needed to use the supercomputing, he directly contacted the Chaohu Mingyue Supercomputing Center and prepared to come and observe.

"Hello, Director Tu."

Xiao Yi stepped forward and shook hands with Director Tu, and then looked at a glass cube in front of him.

The Chaohu Mingyue supercomputer was placed in this cube, and it looked pretty good.

After a few pleasantries, Xiao Yi pointed to the glass cube in front of him and asked, "Is this Chaohu Moon?"

Tu Ran laughed, then nodded and said, "Yes, our Chaohu Moon is inside, and we can also see it from the outside."

"Let me introduce Professor Xiao to our Fei City's 'strongest brain'."

Xiao Yi nodded, "I'm all ears."

Then, Tu Ran began to introduce: "This glass cube is 16.8 meters long and wide, and 13.5 meters high..."

While listening to Tu Ran's introduction, Xiao Yi followed him in.

Tu Ran knew everything, but Xiao Yi only remembered the most critical data.

Double-precision computing peak 12PFlops.

"How high can this computing power peak rank in the world?"

Xiao Yi asked.

Tu Ran was stunned, and then replied: "As for the ranking, our China is not participating in this ranking comparison now, but according to the data now published, it can probably rank around 100 in the world."

Xiao Yi nodded.

Such computing power should be enough to calculate his model.

Then he said, "Well, Director Tu, as I said before I came, I plan to use Chaohu Moon to calculate a model. Can I go up and try it now?"

"Haha, of course no problem."

Tu Ran smiled and nodded, then led the way: "Come with me, the computer room is over here."

When they arrived at the computer room, Xiao Yi also took out his laptop.

Connect the laptop to the supercomputer host, then upload the model, and soon, the calculation began.

And this time, the progress was faster.

Tu Ran was a little surprised, "Professor Xiao, what is the model you calculated, and it takes up so much space."

It's not enough to connect to one server, you have to connect to four servers.

"Something about fluid mechanics."

"I see." Tu Ran expressed his understanding.

At this time, Xiao Yi waved to Wang Hao behind him, and Wang Hao understood, and then put the box in his hand on the table next to him. When he opened the box, he could see that it was full of hard drives.

Then Xiao Yi said, "I'd like to trouble Director Tu to copy some of the calculated data to these hard drives."

For him, the calculation results of these models are not important, because these results are destined to suddenly "explode" within a certain period of time.

The most important thing is the changes that exist in the process from the beginning of the calculation to the explosion.

And the data generated in this process is the most important.

Seeing this, Tu Ran was at a loss whether to laugh or cry, and said, "Okay, I understand why Professor Xiao has to come here specifically to calculate a model. It turns out to be for data."

Xiao Yi also smiled knowingly.

If he only calculated the model results, of course he could directly connect the computer to the supercomputer through the network in the laboratory and calculate it.

But the problem this brings is that the speed at which the data calculated by the supercomputer is transmitted to him is limited by bandwidth, which will be very slow.

So the fastest way is to transport the hard drive in the flesh.

It only takes him half an hour to drive back to the laboratory from here. He can also visit the supercomputing center here. If he waits for the data to be uploaded here and then downloads it there, the transmission speed is estimated to be about the same, or even lower.

This is the so-called physical transportation speed is faster than the network transmission speed.

For example, the amount of data obtained by several observatory observation centers in the original black hole photo was about 5PB in size, and finally several cars were used to pull the hard disk to the research center.

In this way, while waiting for the calculation to be completed, Tu Ran continued to take Xiao Yi to visit their supercomputing center.

Xiao Yi also asked about the relevant opinions on building a supercomputing for the Science Island Laboratory.

In this way, time passed quickly.

Until the evening.

The data calculation was completed, and during the calculation process, the data was also stored in the hard disks brought by Xiao Yi.

A total of more than 300T of data.