For a big job like aerodynamic simulation or structural simulation of the whole machine, the real calculation process must be completed on the supercomputer.

However, the PC that is used as the input and output terminal can still see the saved log files.

In these years, many terminals and servers still run batch FTP, which only captures data once a day, rather than real-time linkage APIs.

Of course, because the computing speed on the server side is relatively limited, it does not seem to be very efficient.

"We mainly encountered the same problems in the two directions of research."

Yao Mengna put the two computers on the table, combed her loose hair a little, and then began to explain:

"One is the computational structural mechanics problem that I just talked about, the structural analysis of the body parts."

She tapped a few clicks on the keyboard of one of the computers, entered an account, and called up a series of calculations.

Then I turned to the second computer and did something similar:

"The other thing is that we're also working on the airflow interference when the aircraft throws large carriers."

"In previous wind tunnel tests, it was found that some munitions, especially some cruise munitions with strong lift, not only will not immediately free fall after they are destroyed with the wing, but will move upwards to damage the wing, and we hope to solve this hidden danger before the seventh batch of aircraft is put into production."

The early Su-27 did not need to consider any large-size ammunition because it basically did not consider ground attack, and there was no external fuel tank, so there was no need to consider such problems.

So, when developing a utility aircraft on the same platform, there are some strange problems that can be easily overlooked.

"I'll take a look at ......"

Chang Haonan came to the first computer just now, bent down and carefully checked the running log of the program.

He Ming, who was following behind, moved a chair very appropriately and placed it behind Chang Haonan.

"Mr. Chang, you sit first."

After a few seconds, he realized something, and he brought a second one to Yao Mengna and put it next to Chang Haonan.

"We use hyperboloid meshes and volume meshes...... Speaking of which, your modeling level is very high, and the geometry process is only a few days away? ”

Geometry processing is the first step in the mesh generation process.

In 1997, the main challenge facing most computational fluid dynamics and computational structural mechanics simulations around the world was the lack of a mature application tool for meshing from CAD models to surface structures.

For existing mesh generation tools, for some models with slightly higher accuracy, it often takes about 6 months, or even longer, to complete the entire generation work.

For example, the simplified model of the Boeing 747LCF took four months.

And the V22 Osprey took more than 9 months.

And from a later point of view, it is clear that there are design flaws.

In contrast, geometry that takes a few weeks to a month is not a big deal and is perfectly acceptable

However, for TORCH Multiphysics, the mesh generation process is typically shortened to 1-2 months, which makes the geometry processing a bit slower.

It's just that Chang Haonan has never had time to put his energy into modeling, and has always used Dassault's software package directly.

"The engineers at Sukhoi brought a new modeling software called KOMPAS, and I slightly adjusted the interface compatibility of TORCH Multiphysics so that it can directly connect to the project files in kom format."

"Originally, it was just a matter of saving trouble, but it turned out that this modeling method was very suitable for our software, and it has been used all the time."

Although this is not the main problem to be solved today, Chang Haonan still paid a little attention.

Damao's electronics industry has stagnated for nearly 10 years and has gradually fallen behind, but when it comes to software and algorithms, it has not fallen behind.

Although there are few hits due to the problem that the market is not big enough (except for Telegram), there are definitely some tricks and tricks in the body.

After a small episode, Chang Haonan once again focused on the grid generation log behind.

"Number of sub-region grid blocks: 253......"

"The number of grid cells is 133 million...... It's a lot, and it's very complicated......"

Mesh Assembly ......

When he saw this last step, he quickly noticed that something was wrong:

"Huh?"

According to the normal process, TORCH Multiphysics should automatically "assemble" the 253 mesh blocks together by interpolating between the grids within the overlapping area.

However, the logs show that the software is stuck at this step.

To be precise, it was the data scraping process that preceded this assembly step that got stuck.

"Too much data?"

This is the first possibility that Chang Haonan thought of.

However, in the logic of the mesh generation algorithm he designed, the computational complexity was specially reduced for large models.

In other words, no matter how complex the model is, it will only take an infinite amount of time to calculate, and it will not lead to problems such as memory explosion.

In short, it is impossible to get stuck here.

"Have you tried manual assembly?"

Chang Haonan asked after thinking for a moment.

"I've tried, but the rest is good, by the time it comes to this central lifter, even if the sub-region mesh is only a small change, the assembly input file has to be modified accordingly, if all is done manually, it will probably take ......"

Yao Mengna raised her head slightly and calculated:

"I need to manually enter about 60,000 lines of code......"

“……”

60,000 lines of code doesn't sound like much, but considering that TORCH Multiphysics can't be automated and has to be manually tuned, there must be a lot of computation and transformation problems involved.

What's even more troublesome is that as a new software, there are fewer people who can complete the process proficiently.

In short, it is clear that it will not be done in a short period of time.

When Chang Haonan tested the software before, it was impossible to test this model with hundreds of sub-regions and hundreds of millions of grid elements because of the tight time and heavy tasks.

In fact, since the release of TORCH Multiphysics for so long, no one has used it for a model of this size, as far as the various users have reported.

That's why I haven't found a problem before.

"If you can't do it manually......

Chang Haonan frowned slightly, and his fingers tapped lightly on the computer shell next to the keyboard.

"Have you ever considered abandoning the structural constraints of mesh nodes and dynamically adjusting the model rules based on changes in object boundaries when the surface is deformed?"

“……”

There was silence.

Yao Mengna and He Ming looked at each other.

Judging from the expressions of the two, they didn't even fully understand the meaning of Chang Haonan's words.

"For example."

Looking at the two with clear eyes, Chang Haonan had no choice but to explain further.

But after touching his body for a long time, he didn't find a pen or paper.

Yao Mengna, who knew Chang Haonan's habits, hurriedly took it out of her bag and put it in Chang Haonan's hand.

"For example, we can compare the computational region to a linear elastomer, and determine the displacement of the grid nodes by solving the system of elastic equations......"

"The algebraic model means that the displacement of the grid is obtained by multiplying the displacement of the moving boundary by a coefficient, which takes 1 on the dynamic boundary and 0 on the far-field boundary, and the inner field is interpolated according to a certain functional law......"

“……”

After some calculations and explanations, Chang Haonan drew a circle on the paper that had already been painted:

"Of course, this is not the case everywhere, for the part that is too complex, you can treat each side of the grid element as a spring, the spring coefficient is related to the length of the side, and when the boundary moves, the position of the new point is determined by solving the force balance problem of the node of the spring system......"

"This allows us to adjust and control the size, shape, and position of the grid points during the calculations, which is much less demanding on the mesh boundaries."

“……”

There was silence again.

"TORCH Multiphysics...... And this feature? ”

After a long time, Yao Mengna asked in a somewhat skeptical tone.

She was obviously personally involved in the development of this software, but after thinking about it for a long time, she really didn't think that there was such a way to play.

"Of course not."

Chang Haonan clicked the tip of the ballpoint pen back:

"But you can change it yourself!"

(End of chapter)