Ye Duzheng barely reached into his pocket, took out the natal wooden sign that his mother had given him and threw it at the other person - it was said that the thing was made of peach wood and could ward off evil spirits.
Of course.
Before taking out the wooden sign, Ye Duzheng reacted first.
The guy who appeared in front of him was not a mummy, but someone who had become famous in the base recently...
An acquaintance, Han Li.
See this situation.
While Ye Du was secretly relieved, he also covered up the initial panic in his heart with a slow speaking speed, and said:
"Comrade Han Li, who I thought it was, turns out to be you..."
to be honest.
Ye Duzheng actually had a very good impression of Xu Yun.
After all, if it weren't for the weather Doppler radar he brought out, the weather center would probably never have a chance to prove itself again.
If that's the case...
It is foreseeable that the entire meteorological center will lose its fighting spirit for a long time.
At the same time, look at it from an industry perspective.
The help of meteorological Doppler radar to the entire meteorology is also obvious.
The emergence of this kind of equipment is likely to open up a new avenue for the meteorological field that has always been unable to see the future - and it is still the kind where China has a dominant position.
Therefore, whether it was based on his job or personal feelings, Ye Duzheng had a very good impression of Xu Yun, and even felt a little grateful.
So after being shocked.
Ye Duzheng did not show any dissatisfaction, but smiled and asked Xu Yun:
"Comrade Han Li, why are you here? By the way, have you had dinner?"
At this time, more than seven or eight hours had passed since the first batch of data was released. The sky had already changed from day to night, and in a few hours it would be almost twelve o'clock.
Not long ago, dinner was delivered to the base.
"Well, I just drank some porridge."
Xu Yun tilted his head towards a certain direction outside the tent. At this time, he could vaguely see several sideline team members busy distributing dinner.
However, tonight's "standard meal" is not of high standard, mostly steamed potatoes and vegetable leaf soup with elm leaves.
The steamed buns grind the teeth, and the elm leaves are bitter.
Xu Yun's ability to drink polished rice porridge was mainly related to his status as a patient, who needed to be nursed back to health during the recovery period.
Then Xu Yun turned his attention to Ye Duzheng's calculation paper and looked at it carefully:
"Huh? Director Ye, this is...a variant of Stokes' equations?"
Ye Duzheng was slightly startled and seemed a little surprised that Xu Yun could recognize the contents of the equation.
However, he soon remembered Xu Yun's identity and nodded lightly:
"Yes, it is the N-S equations with a little change based on vorticity."
According to Lao Guo’s previous introduction.
Xu Yun is a graduate of the Department of Mathematics of Cambridge University, so it is normal for him to recognize the N-S equations. After all, this equation is a major problem in the field of mathematics.
Or put it another way.
Considering Xu Yun's ability to come up with the theory of meteorological Doppler radar, it is strange that he cannot recognize the N-S equations.
Xu Yunze turned around and looked at the crackling scene filled with the sound of abacus, and casually asked Ye Duzheng:
"Director Ye, how is your progress now?"
"schedule?"
Ye Duzheng raised his eyes and looked at Xu Yun for a second, shook his head, and pulled out a wry smile:
"Where is the progress? Comrade Han Li, what you see now is all - I don't even know how to deduce it later."
Ye Duzheng said.
He also held the front half of the ballpoint pen with his fingers to make a small lever, and slapped the end of the pen on the math paper twice. It was obvious that he was a little annoyed.
The calculation of meteorological data was not a secret, so Ye Duzheng didn't want to hide anything.
After all, everyone has a desire to talk.
Then Ye Duzheng sighed and shook his head, ready to change his mind honestly - since the variation he was considering was not feasible, he could only calculate it according to the plan given by Mr. Zhu.
even if......
There are probably some problems with that idea.
And just as Ye Duzheng was writing, Xu Yun's weak voice suddenly came to his ears:
"Director Ye, I have an idea... Do you think it is feasible to add a Bernoulli function after this variant?"
Ye Duzheng's pen tip, which had already written a few letters, suddenly stopped.
After a while.
Ye Duzheng raised his head in surprise and looked at Xu Yun with a mummy-like expression:
"Comrade Han Li, what do you say (fourth tone↓)?"
Under emotional excitement.
Ye Duzheng even had an accent from his hometown of Jinmen.
And opposite him.
Looking at the wide-eyed Ye Duzheng, Xu Yun was actually a little surprised in his heart - he thought that the concept of localized distributed vorticity was relatively complete now.
But soon, he reacted quickly.
Too.
The key figure in the convection-diffusion equation is Suhas Patankar, and judging by his age, he is only in his early twenties.
Although Xu Yun can't remember exactly when he proposed the SIMPLE improvement algorithm, Suhas Patankar is not a genius who became famous at a young age.
He wanted SIMPLE to improve the algorithm, but he proposed that it would be more than ten years later anyway.
Not an exaggeration.
These days, the research on the Navier-Stokes equations in the entire mathematics and physics circles is still in a very primitive state.
Even the SIMPLE algorithm, which is the original version of the semi-implicit method for solving pressure coupling equations, was not proposed until 1972.
Think of this.
Xu Yun decided to help Ye Duzheng in a small way - although he had no plans in this regard before.
But he was naturally happy to do something that could allow Rabbit to catch up with or even overtake the first echelon.
It doesn’t cost any money anyway, just give it a try.
Then Xu Yun paused, quickly organized some thoughts in his mind, and said to Ye Duzheng:
This chapter is not finished yet, please click on the next page to continue reading the exciting content! "Director Ye, what I mean is to add a Bernoulli function after this variant, and then take a curl. Do you think it is feasible?"
"This is what I heard from a senior student when I was at Cambridge University. The scenario they deduced at that time happened to be the same variant..."
Swish——
As a result, Xu Yun didn't finish his words.
Ye Duzheng lowered his head and wrote a function on the paper:
C=p/p u2/2.
This function comes from the equation?(u2/2)=(u??)u uxw, which is the Bernoulli function.
Then Ye Duzheng took the curl according to Xu Yun's statement and got a new formula:
?w/?t=?x[uxw] v?2w.
Even though this formula looks like emojis, it seems like (￣▽￣)~*(￣▽￣)/ (w)[]~(￣▽￣)~* again.
For Ye Duzheng.
The moment he saw it, his heart skipped a beat!
This is......
The evolution equation of w!
At the same time, because ?x(uxw)=(w??)u?(u??)w, this evolution equation can also be rewritten in the form of convection derivatives:
Dw/Dt=(w??)u v?2w.
Write here.
Ye Duzheng paused again, turned to look at Xu Yun, and asked impatiently:
"Comrade Han Li, what's next? What's the next step?"
At this moment.
Ye Duzheng seemed to have returned to the days when he was studying in Chicago.
At that time, he was following a mystery novel serialized in the Chicago Daily News. Every time he finished a chapter, he couldn't wait to update it like crazy.
If it weren’t for the fear of losing the valuable qualification to study abroad.
Ye Duzheng even considered whether to tie the author to a small black room to update - he must update 50,000 words a day, otherwise he will not be able to eat that day!
And opposite him.
Xu Yun signaled Qiao Caihong to move his wheelchair closer to Ye Duzheng.
Then he took the paper and pen from Ye Duzheng's hand and explained while writing:
"Director Ye, if you want to continue deriving this equation, you must first understand the physical meaning of this variant."
"Let's introduce another angular momentum equation here for comparison... You see, the physical meaning should be obvious, right?"
Ye Duzheng looked at it carefully for half a minute, and then quickly said:
"Oh, I get it."
"What is described on the right is due to the elongation of the fluid element, the change in the moment of inertia of the body element, and the viscous moment acting on the body element, right?"
Xu Yun nodded.
The physical meaning of this variation can almost be regarded as the entry-level concept of vorticity in later generations.
That is, the vorticity of the fluid block may change due to its elongation, causing a change in the moment of inertia, or accelerating or decelerating due to viscous stress.
Immediately afterwards.
Xu Yun wrote another Peclet number.
That is, Pe=ud/a, changing the circle at the top, and bringing it back to the original form.
See here.
An unexpected nasal sound suddenly came from Ye Duzheng's nose, and his brows suddenly raised.
He discovered a problem that he had never realized before:
Look at the variations.
Vorticity in a two-dimensional flow is convection and can be diffused like heat, so the analogy to the Peclet number is...
Re=u?/v.
This means that vorticity, like heat, cannot be created or destroyed out of thin air inside a two-dimensional flow.
And it can move from one place to another by convection.
But on the other hand.
∫wdV is conserved for all localized vorticity groups.
That is to say...
The vortices convect through the velocity field and propagate through diffusion, but the total vorticity within each vortex remains unchanged.
In other words...
The boundary is where the vorticity comes from!
This is a concept that Ye Duzheng has never thought of, which means that many of his previous ideas were wrong, and he indeed underestimated the depth of the boundary.
But it also means...
A new model is possible!
To be precise, it should be...
The first truly working new model in meteorology!
To know.
Although the Norwegian school has made great contributions to numerical weather prediction, even now, the entire meteorological industry still does not have a real model.
In fact.
Follow normal historical development.
Meteorology would not develop its first climate model until 1971 by Rassoul.
Moreover, the model established by Rasul predicts not local weather, but a climate model related to global warming.
And right now...
A new road appeared in front of Ye Duzheng.
A new road that no one has ever traveled before.
Looking at Ye Duzheng who looked shocked, Xu Yun looked very calm.
The concepts he mentioned are not based on his personal abilities, but come from the relatively complete knowledge system of later generations, and are nothing to be proud of.
After all, it is different from the current period.
Although the N-S equation is still in the cracking stage in later generations, the general form of analytical solution is still far away - because it is stuck on the nonlinear advection term.
But on the other hand.
It still has analytical solutions in various extreme situations...such as irrotation, inviscosity, etc.
As long as sufficient computing resources are invested in DNS in future generations, even complex fluid flows can be solved.
These are the results that Xu Yun had already established well before his time travel, so that people like Xu Yun who are not in the meteorological field can easily use them for interpretation.
Of course.
Due to professional barriers, Xu Yun's understanding of vorticity is almost finished here.
As for the more advanced concepts of equivalent potential temperature, pseudo-equivalent potential temperature, latent heat, sensible heat, and radiation...
There is no problem if you want Xu Yun to explain their meaning, but any further derivation would be pure wishful thinking.
But that's okay.
At this point, Ye Duzheng has obviously entered the state of 'enlightenment'.
Judging from the ability of this main founder of modern Chinese meteorology, he can probably handle the rest of the process by himself even without Xu Yun's help.
This chapter is not finished yet, please click on the next page to continue reading the exciting content! Not to mention that there is Tao Shiyan, a top leader in weather dynamics, beside him.
So it's very fast.
Ye Duzheng began to deduce the next steps on his own.
"The governing equation of temperature is DT/Dt=a?2T..."
"Then the equation of the temperature field is naturally DT/Dt=?T/?t u?T/?x=a?2T..."
"According to hydrostatic equilibrium and temperature lapse rate, it can be obtained..."
"Brother Shiyan, what do you think about changing the turning point pressure of the piecewise function here?"
"Just what I wanted..."
More than twenty minutes later.
Ye Duzheng wrote another calculation on the paper:
D/Dt(w2/2)=wiwjSij?v(?xw)2 v??[wx(?xw)].
And when I saw this calculation.
Xu Yun's expression wrapped under the bandage also relaxed.
call......
His mission is finally accomplished...
The smart classmates must have noticed it too.
That’s right!
The formula Ye Duzheng wrote at this time is exactly the vorticity quasi-energy equation.
It comes from the scalar product of the upper convection derivative and w, which is the vorticity for the local distribution.
The rightmost divergence term usually integrates to zero and is not needed much like the brain.
The remaining two terms on the right correspond to the vorticity pseudo energy generated by the elongation of the vortex lines, and the vortex pseudo energy lost due to viscous force.
From this formula, we can intuitively see that eddy quasi-energy is like mechanical energy and can be dissipated by friction.
This formula will be mentioned repeatedly when discussing turbulence in later generations, and it can be regarded as an iconic formula.
more importantly.....
As we all know.
Atmospheric diffusion belongs to turbulent diffusion, and there are currently three widely used theories:
gradient transport theory,
statistical theory of turbulence,
Similarity theory.
This formula is the important core of the statistical theory of turbulence. On this basis, a model called WRF was born in later generations.
That's right.
WRF.
This is the most common model for meteorological numerical simulation forecasting in later generations. Many civilian scientists also use this thing to run numerical values at home.
Of course.
Folk science in the field of meteorology is far more intelligent than folk science in the fields of physics and mathematics, and there are obvious differences between the two.
Civil science in the field of meteorology is not so much ‘civil science’.
Rather, it is more like those astronomy enthusiasts who drive with astronomical telescopes to see the stars, and rarely make too many outrageous remarks.
At least I won't always say that I have invented a perpetual motion machine, and then when I look at the drawing, it looks like a Tai Chi diagram...
What civilians in the field of meteorology like most is to quietly run the local weather model at home, and then look at the sky to see if their results are accurate. Overall, it is quite Buddhist.
all in all.
WRF will be a very important model even in 2023, let alone this period.
even if......
What appears at this time is just a prototype.
Later, Ye Duzheng extended the formula to the fields of isobaric surfaces and isopycnal surfaces, and performed calculations related to circulation.
During this period, the girl Qiao Caihong also came forward and watched with interest for two minutes. When she returned to Xu Yun, her expression changed to this:
@v@....
after an hour.
Ye Duzheng and Tao Shiyan worked together to derive the complete vorticity field and fit a special mathematical model.
From Xu Yun's perspective.
This model is still quite different from the WRF of later generations - after all, there is no computing power of later generations these days, but the core logic is still similar.
To put it simply, it first uses cylindrical tangent space and horizontal mapping to construct a local space and map its neighbors to construct an isometric mapping.
Then the conditional local convolution kernel is redesigned to meet the convolution characteristics adapted to local conditions. Adjacent convolution kernels with similar adjacent local features and different geographical characteristics share three conditions.
As for the mathematical mechanism of the model, it is Fourier transform. Ye Duzheng constructed the mixing operation as a continuous global convolution, which can be effectively realized through FFT in the Fourier domain, and the spatial mixing complexity is reduced to a minimum.
The model even takes into account accumulated liquid and frozen water, using total rainfall particles as diagnostic variables, and the number of data sets has reached 20. (Inspiration comes from this paper arxiv/abs/2101.01000)
It can be said like this.
In today's world where computer models have not yet been developed, this model can be said to be the pinnacle of what humans can achieve.
Also, I don’t know if it was Xu Yun’s illusion.
He always felt that Ye Duzheng's model seemed to vaguely touch on the Fourier neural operator...
Of course.
Just a feeling.
After all, he is indeed not very knowledgeable in this area, so he cannot make a specific conclusion for a while.
It may be an illusion, or it may be true.
If it was just a misjudgment, that would be okay.
But if this is true...
So in the current timeline of this dungeon, the fun will be great in the future.
After all, this thing has long gone beyond the scope of fluid mechanics and involves AI...
Then more than ten minutes passed.
Tao Shiyan summarized the data of each group in front of the stage, and Ye Duzheng introduced his model ideas to everyone.
Considering that everyone has different understanding abilities, Ye Duzheng mainly focused on calculations.
That is to say, they focus on telling everyone how to calculate, and the specific principles are ignored for the first time - because what they need now are direct calculation models and tools, and they do not need to know how the tools are derived.
Fifteen minutes later.
Each group started...
Final calculation.
soon.
Crackling——
The sound of abacus and the sound of a few hand-cranked computers were heard in the tent again.
That's right, a hand-cranked computer.
This thing can be regarded as a standard old antique equipment, which is almost extinct in later generations, and has very strong characteristics of the times.
how to say......
In terms of contemporary nature, it is somewhat similar to later DVDs and PHS, which are products of a specific period.
This chapter is not finished yet, please click on the next page to continue reading the exciting content! The hand-cranked computer was invented in 1878. Most of them use a pinwheel structure. They can generally only do four arithmetic operations, square numbers, cubic numbers, square root, and cube root.
.
If you need to input trigonometric functions and logarithms, you need to look up the table.
The hand-crank computers used in China today are all of the "Feiyu" brand, one of the few domestically produced mechanical devices that are better than imported ones during this period.
The first batch of 500 "Feiyu" brand handheld computers was produced, most of which were given to the Second Machinery Department and the Fifth Institute, and some were given to the 156 project that year.
The Fifth Academy used this hand-operated computer to calculate a trajectory from the missile's takeoff point to shutdown, which took almost two months - this is a missile that does not have the ability to change orbit.
In addition, the "Flying Fish" brand hand-cranked computer is much more sophisticated than the one imported from Germany and looks as petite as a girl.
Therefore, it was also given a nickname by the Second Machinery Department that a certain author sounded unhappy about:
Fish girl.
all in all.
At this point, Xu Yun has nothing to do with him - if we talk about written arithmetic and mental arithmetic, he is probably not as good as many seniors of this era.
So he waited alone for the results, while Qiao Caihong and several sideline team members helped drive away the mosquitoes.
........
Half an hour passed.
Lao Guo, who stayed for a while in the morning and then went to continue the research project, got off work and hurried to the scene with Cai Shaohui from the research group.
I don’t know if it was Xu Yun’s illusion.
He always felt that Lao Guo's coughing frequency was much higher than before...
after an hour.
A final report was handed over to Ye Duzheng.
However, Ye Duzheng did not rush to Lao Guo to report. Instead, he and Tao Shiyan randomly inspected several links for verification.
After verification.
Ye Duzheng just took the report and quickly came to Lao Guo.
"Guo Gong, Cheng Gong."
Ye Duzheng first said hello to Lao Guo, then glanced at Cheng Kaijia, who had been staying at the scene next to Lao Guo, and said with a serious expression:
"Fortunately, a new batch of weather forecast results have been released."
"This result has been rechecked by Comrade Tao Shiyan and I, and there are no mathematical errors or omissions."
Lao Guo's expression remained unchanged, but his left hand holding the briefcase still exerted a little more strength.
It can be seen that his heart is not peaceful:
"Director Ye, what have the higher-ups deduced?"
Ye Duzheng took a deep breath after hearing this, opened the manuscript in his hand, and introduced:
"Gong Guo, Gong Cheng, first of all I want to emphasize one thing."
"That is, our meteorological data collection started 12 hours ago, but due to efficiency issues, the results were not available until just now."
"That is to say... the result we derived actually includes the weather forecast for the past twelve hours."
Lao Guo nodded after hearing this.
This sentence is not difficult to understand.
According to their prior arrangements.
The meteorological Doppler radar collects data every 20 minutes. The data is filtered and transmitted to the Capital Computer Institute. The computer then processes it into a parameter field and sends it back to the base, where Ye Duzheng and the others conduct further calculations.
This process was repeated over and over again, and the process lasted for more than ten hours, almost half a day.
Although due to computational efficiency issues, these data cannot produce results instantly or in a short time.
But this situation does not affect the objective existence of the weather forecast results of the past ten hours - it is just that they have lost their timeliness.
But from a reference point of view.
The weather conditions in the past 12 hours can actually verify the derivation results to a certain extent.
It's like someone sent a letter predicting the situation in the next six months, but due to various reasons, a year has passed since it was delivered to the recipient.
Although this letter has lost the meaning of conveying information, it can verify whether the writer's judgment and vision of the current situation are correct.
Think of this.
Lao Guo couldn't help but glance at Ye Duzheng, thought for a moment, and asked him:
"Director Ye, what are the predictions in the report for the past 12 hours?"
Ye Duzheng turned the document over to him, revealing the contents on it, and introduced:
"Guo Gong, look."
"According to the forecast results, there was less Doppler feedback from rainfall particles in the past 12 hours, so there will be no rainfall in the entire Jinyintan grassland."
"But the vertical dust emission efficiency is high, the long straight vectors of aerosols show a regional distribution, and the vertical discriminant variables are very obvious."
"So based on data fitting, we judge that there may be a northwest wind with small intensity of sand and dust between 11:00 and 13:00 noon."
After listening to Ye Duzheng's introduction quietly, Lao Guo immediately looked at Zhou Cai and asked him:
"Assistant Zhou, what is the actual situation in the grassland today?"
As the assistant to the factory director of the base, Zhou Cai's weather conditions on that day are data that he must follow up and summarize every day.
At this time when digital communication has not yet appeared, he got the overall weather conditions even earlier than Ye Duzheng and Tao Shiyan.
Hearing Lao Guo's question.
Zhou Cai immediately took out a small book, flipped through a few pages, and said quickly:
"There is indeed no rainfall record on the grassland in the past twelve hours... To be precise, there is no rainfall record in the entire Haiyan County. However, there was a light rain in the neighboring Huangyuan County, which lasted for about 40 minutes."
"As for the sand and dust...oh, there is indeed a sand and dust record, which was reported by a comrade from the Animal Husbandry and Sideline Team."
"The starting point of the dust was near the Sixth Branch Factory. The time was around 1:30 in the afternoon. The direction... was indeed northwest wind."
Hear this.
The atmosphere at the scene suddenly became a little subtle.
It didn't rain, and there was dust again...
Forecast for the first 12 hours.....
It's actually accurate?
After a while.
Cheng Kaijia, who had been silent all this time, spoke, his face still maintaining a restrained calmness:
"The information is correct, but some comrades, I think this situation has a certain degree of chance. At least these results alone cannot explain too much."
"First of all, it's very common here in the grassland to not rain for half a day. Secondly, if I remember correctly, the dust that appears on Jinyin Beach this season should basically be caused by northwest winds."
"So in order to determine whether the deduction results are accurate, I think a new round of evaluation needs to be continued."
Hear this.
Several people present nodded in agreement.
Students who have studied geography should all know this.
In summer.
The southwest monsoon reaches the Bay of Bengal and then hits the Tibetan Plateau as it advances northward, dividing into east and west branches:
One wind turned eastward along the Himalayas and blew westward.
The other branch flows along the direction of the mountains to southwest my country, intensifying the water vapor channel effect, increasing precipitation on the edge of the plateau, and further intensifying drought in the interior of the plateau due to the rain shadow effect.
So in this place in the West Sea.
In winter and summer, northwest wind accounts for more than 80%, and southeasterly wind occurs occasionally.
So just relying on the description of no rain for half a day and small-scale northwest dust does not prove much.
To prove that the derivation results are accurate enough, a larger test must be passed.
Think of this.
Lao Guo looked at Ye Duzheng again and asked him:
"Director Ye, how does the derivation result predict the next weather? - Hmm...for example, is there any forecast of rainfall?"
"It's raining..."
When Ye Duzheng heard this, a subtle expression appeared on his face:
"Of course, and... the time is very close to now."
Lao Guo felt a chill in his heart and asked:
"Oh? When?"
Wow——
Ye Duzheng turned over another page of the report, looked at the results above and said to Lao Guo:
"Three hours later, that is, between 11 pm and 1 am, there should be a fight that lasts for half an hour..."
"Thunderstorm."
............
Note:
Yesterday, in order to change my biological clock, I woke up very late at night and coded all night, so I updated it in the early morning.
I have said before that this situation is very common when updates are released. The quantity will not be small, but the time may not be fixed, so please don’t rush me. If there is no update that day, I will ask for leave in advance.
