Chapter 941: A battle of wits and courage with the air
Of course, the idea of backstabbing is just Chang Haonan's inner complaint.
If you really want to say it out loud, it would be a bit of a fuss.
Although Dassault has cooperated with Torch Group, it is also one of the important users of TORCH Multiphysics software, and even purchased a supercomputer specially launched by Sugon Group.
But in the field of numerical calculation, after all, the relationship is only between the manufacturer and the customer.
The two parties have not formed any form of business alliance, and the Falcon Z's cooperative research and development agreement does not specify the form in which engineering documents must be submitted.
However, this scenario of "partners abandoning themselves and choosing similar products from friends" is really too NTR.
Therefore, Chang Haonan downloaded the project file.
In fact, after a certain minor version, TORCMultiphysics is even compatible with opening and editing cmph files.
At most, some exclusive functions of COMSOL Multiphysics will not be available.
Soon, a wing that had been divided into grids appeared on Chang Haonan's computer screen.
Moreover, the details have been included.
If you zoom in, you can even see the flaperon model, as well as the winglets.
Strictly speaking, it is a wingtip sail.
It should be based on some designs of the Airbus A320.
Of course this is normal.
Aircraft design, especially civil aircraft design.
Easy elements will soon spread from one place to another.
“Let me see what you are calculating...”
Chang Haonan began to further check some of the data contained in the project documents——
In 1997, when the first trial version of TORC Multiphysics was released, the only common and convenient storage media was 3.5-inch floppy disks.
In order to avoid the situation where the project file is so large that it needs to be divided into several disks for storage, Chang Haonan separated the editing and running log files from the project file.
Later, this became the practice of almost all numerical calculation software.
As a result, the boomerang has now hit his head.
In the absence of information, it took Chang Haonan about half an hour to figure out what issues Dassault engineers were studying.
Simply put, they should be preparing to design a wing with extremely low drag in the transonic range.
Since the small-thrust turbofan modified from the M88 core aircraft is very powerful, as long as the resistance of the fuselage, especially the wings, reaches the standard, then this aircraft can completely fly at Mach 0.9 or even Mach 0.95. Economical and quiet sailing at "quasi-sonic speed".
This means that compared to competitors currently on the market whose speeds are generally Mach 0.7-0.8, Falcon Z can save about 15% of flight time.
It is obviously very attractive to the customer groups targeted by business jets.
And it’s also a very good publicity stunt.
However, it is impossible for the Falcon Z to make its wings into delta wings or swept wings.
To achieve excellent near-sonic performance on a generally straight wing, there is no future by optimizing the airfoil alone.
Attention must also be paid to the details of the wing surface.
This engineering document is to calculate the air flow near the wing surface.
It sounds similar to the work that Chang Haonan did to optimize the J-8C airfoil.
But the level of sophistication is much higher.
After all, within the allowable range of the structure, fighter aircraft do not need to consider the noise and jitter caused by airflow.
In fact, even considering the structure alone, a straight wing with a large aspect ratio is much more complicated than a delta wing.
Therefore, judging from the content presented in this engineering document, Dassault engineers seem to be still in relatively early stages of research.
When I switched to COMSOL Multiphysics, I most likely took a fancy to the high computational efficiency advertised by it.
Otherwise, there is a high probability that this airfoil will not be able to keep up with the Falcon Z schedule.
Of course, a passenger aircraft has a relatively simple structure.
Many models (such as the MA-60 of that year) even provide wings of different designs to customers as options.
But it would definitely be better if it could be made standard in the starting lineup.
But...
Looking at the wing modeling on the screen, Chang Haonan gently raised his chin with one hand.
"This calculation result seems... to have some problems?"
Before Samsung Offshore Engineering caused this incident, Chang Haonan had been studying the finite volume method out of interest. A solution to the problem of high computational weight when encountering viscoelastic constitutive equations.
In fact, he has found a constitutive equation that does not involve diffusion terms, but he has not yet found a specific solution method.
In that process, Chang Haonan used a large number of existing calculation examples at hand to provide "learning materials" for the high-order data dimensionality reduction process.
Therefore, although he himself cannot give numerical calculation results that are accurate to a certain number of digits like a computer, he still has some intuition about the characteristics, or trends, of the results.
But the several sets of results calculated by Dassault were not in line with his intuition. "Professor Liu."
Chang Haonan raised his head and looked at Liu Hongbo, who was sitting on the sofa and had drank an unknown number of cups of tea.
“Huh?”
The latter was bored at this time and was wondering whether to take the initiative to leave, when he heard the voice of his boss:
"Mr. Chang, please tell me."
"Your COMSOL Multiphysics version 2.5 is correct. Right? "
Chang Haonan asked.
“Yes.”
Liu Hongbo answered with some confusion.
"That's good."
Chang Haonan said, returning his eyes to the screen, and then forwarded the email from Dassault to Liu Hongbo's mailbox:
“I sent you an email, which contains a COMSOL Multiphysics project file. When you go back, open it with their latest version of the software. Don’t change anything, just run the calculation from scratch.”
Although Liu Hongbo still didn’t know what Chang Haonan wanted to do, he still nodded:
"Okay, I will send you the results as soon as possible."
However, Chang Haonan shook his head directly:
"No...I don't need the results."
"You're here Then extract the log of this calculation process and send it to my email.”
……
Liu Hongbo's movements were quite fast.
Less than two days later, Chang Haonan received the log file he sent.
txt format.
COMSOLM Multiphysics was released independently several years earlier than in history, so many software-level details are not good.
Typically, logs are stored directly in txt format.
Of course, for a hard-core ruthless person like Chang Haonan who checks logs with naked eyes, this is indeed a lot more convenient.
And the results of the inspection...
also confirmed his guess two days ago.
"What a fuck..."
Chang Haonan leaned back in his chair and laughed and cursed to himself——
Since nearly two months ago, he began to think about how COMSOL would solve the high computational weight problem of viscoelastic constitutive equations.
And the result is...
It is not solved at all...
It can be seen from the log that the calculation process is to directly follow the general method and use the grid-centered FVM discrete method to calculate N-S equations are solved numerically.
However, the situations with these characteristics are indeed extreme and are not actually common.
In particular, COMSOL’s past regular customers were generally schools and small and medium-sized enterprises with limited strength and financial resources.
Even less common.
Most of the new customers who started trying COMSOL Multiphysics after version 2.5 have not yet fully adapted to it.
Just like Dassault, they have already started using it for projects, but they are still in a state of exploration.
I don’t even know there is a problem with the result.
So, so far, the Swedes should not have received relevant feedback.
In other words, they probably didn’t know about or thought about the problem from beginning to end...
And Chang Haonan...
Then I have been battling with the air.
Thinking of this, he shook his head with a wry smile, then opened the Word document, preparing to write a memo to inform Dassault of the situation.
After all, Falcon Z is a joint development project.
If something goes wrong in a big job like the wing, it will inevitably affect the progress of the entire project.
By the way, let them go back to the calculation tools of the past.
Thanks to the fact that it is not bound to the finite volume method, TORCMultiphysics does not need to face the problem of high calculation weight when calculating the viscoelastic constitutive equation.
The price is that it consumes more computing resources.
But no matter what, it's better than figuring out the problem in the end.
As for the competitor COMSOL...
Chang Haonan already has a rather "evil" idea.
(End of this chapter)