Chapter 946 Chang's Turbulence

The Numerical Calculation Business Department headed by Liu Hongbo and the Technical Department headed by Wei Yongming are two non-affiliated departments of the same level.

In fact, Chang Haonan first decided that Torch Group would take over part of the numerical calculation business. The original intention was to provide after-sales service to TORCH Multiphysics users who had a demand for numerical calculation but did not have sufficient capabilities.

From this perspective, he once considered setting up the Numerical Calculation Business Department as a secondary department under the Technical Department.

But before he could finalize this matter, this business, which was originally just a foil, became a new hot spot.

Many small companies or general universities saw that Torch Group provided this service, and simply gave up their plans to start simulation from scratch and directly outsourced all related businesses.

At first, Chang Haonan thought that this was a bit of a delay, so he set a rule to give priority to those users who purchased TORCH Multiphysics.

However, the business volume did not decrease at all.

In the end, there was no choice but to continuously expand the scale of the Numerical Calculation Business Department and then officially list it as one of the company's main businesses.

Later, they were even able to surpass the profits of the software department from time to time.

Therefore, although there was cooperation between the two, most of the time they were responsible for their own areas.

As for the "secret trump card", since it was prepared for the 2.0 version of TORCH Multiphysics, and Liu Hongbo had not used it yet, he naturally knew nothing about it.

Logically speaking, for such projects with a large impact, for the sake of safety, the most proficient calculation tools should be selected, that is, the old version with stable performance.

But at the moment, Dassault is pushing too hard.

In addition, from what Chang Haonan said, this trump card was developed by him himself.

So, Liu Hongbo was willing to give it a try...

...

Soon, about a dozen business backbones were pulled into an office on the top floor of Torch Group.

And Chang Haonan had already sat at the head of the conference table, waiting for everyone.

In fact, after serving as the chief planner of the Aviation Power Group and a professor at Beijing University of Aeronautics and Astronautics, he rarely returned to Torch Group to work.

Therefore, some new employees may not even have seen Chang Haonan himself.

Fortunately, the people who just walked in looked familiar, and they should be from the earliest members of Torch Group.

Liu Hongbo arranged seats for the rest of the people, and then he sat on the left hand side closest to Chang Haonan:

"Mr. Chang, according to your requirements, these comrades have either participated in the helicopter project of Bingfei Group with me, or originally jumped from the Aviation Industry Corporation of China, and have experience in aircraft-related design..."

When the numerical calculation business department was expanded a few years ago, there were relatively few people in the whole of China who could master this skill.

Moreover, a considerable number of them were Chang Haonan's "apprentices" brought out by the aviation industry system.

For example, Lin Shikuan and others from the 601 Institute.

During that period, Torch Group happened to be named and praised by the superiors as a typical "high-tech enterprise".

Therefore, in order to show support for Chang Haonan and to solve the work problems of some non-staff personnel after the reduction of the establishment of state-owned enterprises, the two sides hit it off and transferred the work relationship of some of them to Torch Group.

At that time, the latter was still an enterprise under the system of the Academy of Sciences, and both sides were happy.

Who would have thought that within two years, Torch Group would become a wholly-owned subsidiary of Aviation Power Group...

Now it has become "supporting the enemy".

However, it was precisely because of these people that Chang Haonan had the confidence to take on this wing design task alone two days ago.

Otherwise, he and Liu Hongbo alone...

They would not be able to catch up with the deadline even if they worked themselves to death.

"Comrades, I now have a calculation application submitted by the French Dassault Group, which is a wing design for a high-speed business jet..."

"..."

After everyone sat down, Chang Haonan first introduced the general situation of this project in a few words at the fastest speed.

Then, the topic was shifted to the focus of today:

"This job is time-sensitive and the task is heavy. The old version of TORCH Multiphysics has a very low error tolerance rate and there are no chances for trial and error, so some new computing tools are needed to improve efficiency."

"Originally, the new software version 2.0 was optimized for this kind of external flow field simulation computing task, but the software itself has not been tested and packaged yet, so it cannot be used directly."

"Fortunately, one of the optimizations related to CFD has been completed, and it can be used in the current version 1.32 of the software in the form of a custom function module..."

"..."

TORCH Multiphysics can be welcomed by many top research institutions. In addition to its excellent performance, this highly free custom module is also a major reason.

It allows high-level users to edit models or algorithms by themselves and integrate them into the software.

Although there are still some limitations, for the software industry in 1997, it was almost equivalent to unlimited imagination.

……

Almost everyone sitting in this conference room had worked in the same R&D team as Chang Haonan in the past.

So, when they heard him mention a new optimization, everyone took out their notebooks as if by reflex -

It was so familiar.

It was as if they were back to the days when they worked on projects together in the past.

Chang Haonan, who saw this scene, smiled knowingly at this moment.

Then he put down the teacup, stood up and walked to a mobile blackboard, just like he did in the past:

"In short, turbulence is still the main factor restricting engineering fluid simulation. After taking into account the requirements of efficiency and accuracy, the widely used method is still mainly based on the Reynolds average equation."

"But for complex engineering fluid motion, such as flow separation and transition prediction, a turbulence model that takes into account different flow states is required, which will inevitably greatly improve the efficiency and accuracy of engineering fluid simulation."

"Therefore, I made some improvements to the two-equation model that was commonly used in the past, only transporting turbulent kinetic energy, and using high-order dimensionality reduction methods to algebraically solve other turbulent variables..."

At this time, someone suddenly whispered:

"The new turbulence model...why not call it Chang's turbulence?"

The half-joking tone triggered a good-natured laugh, which just relieved the tense atmosphere in the conference room.

Amidst the laughter, more than one person actually wrote "Chang's Turbulence" as the name in his notebook...

While chatting and laughing, Chang Haonan had already written down the N-S equation that everyone was familiar with on the blackboard.

Of course, for the speed range of the Falcon Z project, there is no need to consider volume force and additional heating terms.

Q/t+(F-Fv)/x+(G-Gv)/y+(H-Hv)/z=0.

"The Cartesian coordinate system directly coincides with the physical position of the computational domain, but additional processing methods are required for the density change of the grid, which is not suitable for direct programming calculations. Therefore, it is necessary to first convert the physical space (x, y, z, t) into the computational space (ξ, η, ζ, τ)..."

"From the closure problem of turbulent simulation that we have often solved in the past, it can be found that the solution and determination of the mixing length need to be linked to the boundary conditions and flow conditions of the turbulent field, and there is no universal equation. In order to solve this problem, I will seek the mixing length distribution of the spatial turbulent structure as a means to establish a universal connection between Reynolds stress and the time-averaged flow field..."

"..."

The content introduced by Chang Haonan has made a qualitative leap in difficulty compared to the original.

Especially at the level of mathematical theory.

Fortunately, other people have not been idle over the years.

The accumulation of a large amount of computational experience has also enhanced their understanding of computational models and algorithms to some extent.

Therefore, although they could not fully understand all the theoretical knowledge used by Chang Haonan, at least everyone could still follow his train of thought.

Compared with the situation in the past when he would be interrupted and asked questions every time he spoke, it was much better.

And this was the most precious wealth that Chang Haonan had left behind since his rebirth...