My IQ has been increasing year by year.

Chapter 187 Why don't they just rob it!

In early September, the evening breeze in Huizhou already carried a hint of coolness.

A black Santana stopped at the bottom of the steps of the Physics Department building. The door opened, and Fang Shi got out of the back seat.

He was wearing a slightly wrinkled white shirt, his tie was loose and hung crookedly around his neck, and he was carrying a black briefcase. He walked with heavy steps.

The security guard in the lobby saw him and quickly stood up to greet him.

"Dean Fang, you just got back from your business trip?"

The Taoist priest nodded, said nothing, and walked straight to the stairs.

The Taoist priest walked to his office door, took out his key to open it, and turned on the desk lamp instead of the main light.

He threw his briefcase on the table, picked up the landline phone, and dialed a few numbers.

"Zhang Yuan, come to my office and call Lin Fang."

After finishing the call, Fang Shi leaned back in his chair, took out a pack of cigarettes from the drawer, and lit one.

Less than five minutes later, a series of hurried footsteps echoed down the corridor.

Zhang Yuan pushed open the door and walked in, with Lin Fang following behind him. Zhang Yuan was holding half a half-eaten steamed bun in his hand.

"Teacher, you've returned from the capital?"

Zhang Yuan casually placed the steamed bun on the coffee table next to him, pulled over two chairs, and sat down with Lin Fang.

The Taoist priest didn't say anything, took a deep drag of his cigarette, and then stubbed it out in the ashtray.

He reached into the black briefcase, pulled out a thick document with a foreign language cover and the Ministry of Railways' red seal.

The sorcerer threw the document onto the table in front of Zhang Yuan.

"have a look."

The sorcerer's voice was deep.

Zhang Yuan picked up the document, flipped through a few pages, and immediately frowned.

"German? A Siemens technical manual?"

"To be precise, it was a page they deliberately let us see at the negotiating table this morning."

The sorcerer gave a cold laugh.

Lin Fang leaned over and took a look. It was a chart with a high-speed train drawn on it and several parabolic pressure waveforms next to it.

Representatives from Siemens and Kawasaki were present at this morning's meeting.

The sorcerer leaned back in his chair, watching the two of them.

"The German representatives presented this diagram and asked us what the standard cross-sectional area is for existing railway tunnels in the country."

Zhang Yuan raised his head.

"Around one hundred square meters, that's a common size."

"Yes, one hundred square meters."

The Taoist priest nodded.

"Then they laughed and told the negotiation team that the aerodynamic shape of their ICE3 train was based on the cross-sectional area of ​​tunnels in their country. If we didn't buy their complete aerodynamic software license and just built the locomotive ourselves, once the speed exceeded 250 kilometers per hour, the micro-pressure wave generated instantly when entering the tunnel could shatter all the windows of the carriages."

The office fell silent.

Zhang Yuan's expression changed.

"This is intimidation. We can modify the front of the car ourselves by conducting wind tunnel tests."

"How should we modify it?" Fang Shi looked at him. "Do we have full-scale transonic data?"

Zhang Yuan opened his mouth, but no words came out.

No.

Currently, domestic high-speed wind tunnels cannot generate high-precision data under extreme conditions.

However, computer simulations are hampered by the limitations of traditional fluid dynamics equations in terms of computing power.

"I told them that we could calculate the data ourselves."

The sorcerer's voice suddenly rose a little.

"Guess what they said?"

Zhang Yuan and Lin Fang looked at the sorcerer.

"Their expert said in front of all of us that, given the current level of fluid dynamics algorithms and computer hardware in China, it would be impossible to calculate a full-scale aerodynamic model for three-dimensional transonic conditions within ten years."

The Taoist priest pointed to the documents on the table.

"Therefore, they dared to ask for 200 million euros just for the license of the underlying code of this one pneumatic data, and it was a black box license, only giving the result and not the process."

Zhang Yuan suddenly stood up.

"Two hundred million euros? A black box? Why don't they just rob it!"

Zhang Yuan's chest heaved violently.

"They're just blatantly robbing us."

The sorcerer looked up at the ceiling.

"Because they've figured out your weakness. If you can't produce your own data, you can't prove that you can build a safe train without their authorization. If you don't pay, the negotiations can't continue."

Lin Fang's face also looked very pale.

"What did the ministry say?"

"The ministry is stalling for time. I've been in meetings every day during my stay in Beijing."

The sorcerer sat up straight and placed his hands crossed on the table.

"The second round of key contacts is scheduled for early next month. The ministry is under a lot of pressure. If we can't come up with some theoretical basis, we might really have to accept the 200 million euros by the nose."

The Taoist priest looked at Zhang Yuan and Lin Fang.

"Several other universities in China are working hard to develop wind tunnel models, while the task assigned to USTC is to simulate the underlying fluid algorithms."

The sorcerer paused.

"I spent three days running around Beijing, begging and pleading, and finally managed to snag a 48-hour network computing node for our lab from the Chinese Academy of Sciences Supercomputing Center."

Zhang Yuan's eyes lit up.

"Supercomputer time? When?"

"Cut it for us at dawn twenty days from now," the sorcerer said.

"However, supercomputing is not for trial and error."

The sorcerer stared at Zhang Yuan.

"In the next few days, we will run a sandbox verification version of the underlying algorithm of the 3D model on our four local servers. If the local code overflows with memory, it will still crash and become useless code when it is transferred to the supercomputer. The machine time allocated by the country cannot be wasted like this."

Zhang Yuan's fist slowly clenched.

"This isn't a death order, and I know it goes against the current logic of computing power."

The Taoist priest stood up, walked to the window, and looked at the dark night outside.

"But the country needs us. No matter how Siemens mocks us, we have to try our best, even if it means hitting a brick wall. If we succeed, the country will have a trump card to fight back at the negotiating table. If we fail, at least we will have figured out the bottom line of this path."

The Taoist priest turned around and patted Zhang Yuan on the shoulder.

"Do your best. I need to go to Beijing again in the next couple of days. Once you've built the model, go ahead and test it. If you have any problems, contact me by phone."

Zhang Yuan looked at the bloodshot eyes of the sorcerer and nodded heavily.

"Understood."

Zhang Yuan picked up the documents on the table.

"Lin Fang, let's go down to the basement."

first day.

The door to the laboratory on the second basement level was slammed shut.

Zhang Yuan and Lin Fang threw their bedding rolls in the corner and turned on the four servers.

The room was soon filled with the roar of the fans starting up.

The whiteboard was pushed to the center of the room, and Zhang Yuan took a marker and wrote a long string of Navier-Stokes equations on it.

"First, build a sandbox model."

Zhang Yuan stared at the whiteboard.

"Import the geometric parameters of the front of the vehicle, cut the mesh a little coarser first, and run it once to check the boundary conditions."

Lin Fang sat in front of the computer, her hands flying across the keyboard.

"Import complete. Initial grid size: 3 million."

Run the standard solver.

The green cursor bounces in the black command line.

Half an hour later, the cursor stopped.

A red message pops up on the screen: The equation does not converge.

Zhang Yuan walked over and looked at the error log.

"The turbulence model diverged at the tip of the car's nose; the mesh was too coarse to capture the details of airflow separation."

O

"Continue to refine it?" Lin Fang asked.

"Detailed"

Day three.

The air in the laboratory began to become murky.

Several empty instant noodle boxes were piled on the table, and Zhang Yuan's beard had grown quite a bit.

"The grid has been increased to eight million."

3

Lin Fang pressed the Enter key.

The server fans became increasingly loud, like a truck struggling to climb a hill under heavy load.

This run took three hours.

Zhang Yuan stood in front of the screen, his eyes fixed on the scrolling data.

"The pressure level is rising..."

'

Zhang Yuan muttered to himself.

"We've entered the transonic range, Mach number 0.8..."

'

Suddenly, the scrolling data paused for a moment.

Immediately afterwards, a large area of ​​NaN appeared on the screen.

The calculation result overflowed and became an invalid number.

"It exploded again."

Zhang Yuan slammed his fist on the table, causing the cup next to him to shake.

Lin Fang rubbed her sore eyes.

"Nonlinear convection terms cannot be handled. As soon as the speed enters the transonic range, the compressibility of air changes abruptly, and traditional difference schemes simply cannot stabilize."

Zhang Yuan walked to the whiteboard, picked up the eraser, and forcefully erased part of the formulas on it.

"It needs to be changed. Let's try a welcoming style."

Day .

The trash can was overflowing with cigarette butts and waste paper.

Zhang Yuan sat in the chair, staring blankly at the ceiling.

Lin Fang was asleep, lying on the table with a coat draped over her shoulders.

The screen still displayed the glaring NaN.

We've tried all the conventional methods.

They tried various mainstream fluid dynamics algorithms, but as soon as the mesh accuracy increased, the computational load exploded exponentially, and then the nonlinear terms collapsed at a certain moment.

If the grid precision is reduced, the calculated data will be a complete mess, so bad that it won't even fool your own people at the negotiating table.

Zhang Yuan picked up the cigarette pack on the table, took out a shriveled cigarette, but didn't light it; he just put it in his mouth.

One-third of the twenty-day deadline has already passed.

Zhang Yuan closed his eyes, his mind filled with the arrogant smile of the foreign representative.

Can't figure it out in ten years?

Are we really going to be watched to death by them?

Zhang Yuan opened his eyes and turned to look at Lin Fang, who was fast asleep.

Zhang Yuan slowly sat up straight, exhaled the smoke from his mouth, walked to Lin Fang's side, and nudged her shoulder.

"Lin Fang, wake up."

Lin Fang groggily raised her head, her face still bearing the red marks from her sleeve.

"What happened? Did you get through?"

"no."

Zhang Yuan looked at her.

Do you remember the matrix Chen Zhuo wrote about last year?

Lin Fang paused for a moment, then her mind cleared up a bit.

"Chen Zhuo? Are you crazy? That was two-dimensional. This is a three-dimensional full-size model. The number of meshes is several orders of magnitude different."

"The logic is the same."

Zhang Yuan's eyes gleamed with a desperate, frenzied enthusiasm, like someone grasping at straws when they're already ill.

"We're currently stuck on continuous equations, while Chen Zhuo's approach is discrete. What if he could increase the dimension of that matrix and fit it into a 3D model?"

Lin Fang looked at the data on the screen and bit her lip.

Zhang Yuan turned around, walked to his desk, and grabbed the landline phone.

"Pull him down to save his life."

Foreign language reading room on the third floor of the old library.

The long wooden table by the window was bathed in sunlight.

Chen Zhuo sat on an old wooden chair, with a yellowed English monograph open in front of him, titled "The Fundamentals of Algebraic Topology".

He read very slowly, occasionally jotting down a few symbols in the notebook beside him.

Sitting opposite him was Su Wei.

A heavy IBM laptop sat in front of Su Wei, its screen displaying a dense array of financial data lines. She wore headphones, her brows slightly furrowed, seemingly checking the historical price fluctuations of a particular stock.

The desktop was quiet, with only the sound of pages turning and the occasional click of the mouse.

A soft footstep on the old wooden floor broke the silence.

The librarian walked over to the table, wearing reading glasses, and gently tapped twice on the edge of Chen Zhuo's table.

Chen Zhuo put down his pen and looked up.

"You must be Chen Zhuo, right?"

The administrator lowered his voice and pointed towards the door.

"Go to the front desk and answer the phone. It's the Department of Physics calling. They said they called several places before finally finding this place, and they sounded quite anxious."

Chen Zhuo was taken aback.

He gestured to Su Wei across from him, stood up, and walked towards the lending desk.

On the wooden service counter, there was a slightly faded landline phone with a microphone placed next to it.

Chen Zhuo walked over and picked up the microphone.

"Feed".

"Chen Zhuo, that's me, Zhang Yuan."

The voice on the other end of the phone sounded like it was being sanded on sandpaper, with a muffled hum of a fan in the background.

Chen Zhuo slightly adjusted his posture.

"Senior Brother Zhang?"

"Did I disturb your reading?"

Zhang Yuan gave a wry smile.

"I called your dorm first, and your roommate answered. He said you came to the old library with a stack of foreign language books. I searched through the internal address book for a long time before I could call the old library."

Chen Zhuo listened quietly.

"What's the matter? Is it urgent?" Chen Zhuo asked.

"That's going to kill you."

Zhang Yuan swallowed hard on the other end of the phone.

"Dean Fang secured the supercomputer's time, but we need to run the underlying algorithms locally first. However, we are completely stuck here. The three-dimensional transonic model cannot be pushed, and the continuous equations all crash."

On the other end of the line, Zhang Yuan's voice carried an undisguised sense of powerlessness.

"Chen Zhuo, I hope you can come and take a look."

Chen Zhuo turned his head and looked at the old camphor tree swaying in the wind outside the window.

"Okay, I'll be right there."

Chen Zhuo's voice remained gentle and calm.

After hanging up the phone, Chen Zhuo returned to his seat.

He neatly folded the draft paper, tucked it into the English monograph, and then stuffed it into his backpack.

Su Wei took off one of her earphones and looked at him.

"Are you leaving?"

"Um."

Chen Zhuo stuffed the notebook into his backpack.

Su Wei glanced at the clock on the wall.

"It's only 2 PM. Didn't you say you were going to finish this book today?"

"There's been a bit of a problem at the physics department."

Chen Zhuo zipped up his backpack.

"My senior brother contacted me, and they didn't seem to be doing well."

Chen Zhuo turned around, looked at Su Wei, and slightly raised the corners of his mouth.

"I'll go see if I can help. I'll finish reading the book; there's no rush."

Su Wei didn't say anything more, put her headphones back on, and returned her gaze to her financial data.

"See you tomorrow."

"See you tomorrow."

1