So is anybody else excited about the new 20 KM CFD that surrounds the plane, coming in SU 11? This looks very fascinating to me and appears to make the MSFS flight model even more sophisticated. I did some asking around and from the responses I got, I don't think something like a 20 KM CFD surrounding the plane has been done before in a home market flight simulator.

Some of the screenshots of the new 20 KM CFD look amazing:

 

 

If it's true that a 20 KM CFD surrounding the plane hasn't been done before in a home market flight simulator (based on the responses I got when I asked around), this is really ground breaking flight model technology for MSFS. Am I one of the few people here at Avsim that is excited about this new technology for MSFS?

Edited November 4, 20223 yr by abrams_tank

For everyone else who had to Google this, it's computational fluid dynamics.

I am excited to see it in action in SU11, but I'm more excited to hear what they have planned for the future of weather. I remember they talked about your wake punching holes in clouds, and heavies creating turbulence behind them. Will we eventually see hail? Rotor clouds? Microbursts and tornadoes and St.Elmo's fire?

This is just the beginning. (My only concern is Asobo likes to overdue the first iteration of stuff: Icing. Turbulence. Lightning. Then they roll it back so far that it's like it doesn't exist anymore. And THEN they get it right to where it should be.)

I wonder why it is measured in KM while for everything else NM is the way to go in aviation.

The proof of the pudding is in the eating.

We’ll have to see how it improves on the flight dynamics only when it’s out.

Hope this will actually be an improvement unlike the overcooked turbulence model that’s been recently introduced.

This is a great first attempt in SU11 by MS/Asobo to realistically simulate atmospheric airflow, thermals, turbulence of various kinds, vortices, etc and the aerodynamics/physics interaction of said airflow with the aircraft (thus the 20km cocoon around aircraft). Hopefully they continue to build on it in SU12 and beyond.

A lot great information and findings are in this thread on the official forums https://forums.flightsimulator.com/t/testing-the-new-airflow-simulation/549454 for those wanting to learn more about what's coming. The updated weather debug window provides a lot of info now on all the factors involved and what's being simulated. Also this thread https://forums.flightsimulator.com/t/cfd-is-amazing/549365 on both aircraft CFD and atmospheric CFD is worth a read. Especially cool how turbulence now is actually based on interactions of various airflows/thermals/etc, such as rotor turbulence in the screencap below from the first thread.

Thermals themselves are based on a multitude of factors as stated in that thread:

• Position of the sun (Day of year, time of day, location)
• Temperature
• Wind speed
• Clouds
• Albedo (Colors) of the satellite imagery
• Trees
• Water
• Scenery
• Trees
• Terrain slope

Edited November 4, 20223 yr by lwt1971

13 minutes ago, lwt1971 said:

Thermals themselves are based on a multitude of factors as stated in that thread:

• Position of the sun (Day of year, time of day, location)
• Temperature
• Wind speed
• Clouds
• Albedo (Colors) of the satellite imagery
• Trees
• Water
• Scenery
• Trees
• Terrain slope

And trigger.

For example a combine harvester working in a field can trigger the release of a thermal over the field but I beat they don't model that! 😁

1 hour ago, mspencer said:

For everyone else who had to Google this, it's computational fluid dynamics.

I KNEW it couldn’t be Cheyenne Frontier Days. 

2 hours ago, abrams_tank said:

So is anybody else excited about the new 20 KM CFD that surrounds the plane, coming in SU 11?

Heck yeah very excited here.  I'll be sleeping with my hands on top of the covers until SU11 releases.

I love where desktop flight simulation is heading, really exciting. Is this tech active in the su11 beta? 

Not long to wait now, but I'm certainly looking forward to seeing it in action.

Would rather have CFD than CTD any day.

Has  been done in X-Plane for some time, I should point out.

You can actually see the vertical components of the airflow around an aircraft in that simulator using the available on-screen output, and X-Plane has modelled since XP10 the deflection of air currents due to orography, as well as wake turbulence, shear and even microbursts.

The difference IMO is that ASOBO is taking a slightly more elaborate approach to the modelling of some of these currents, including the way convection is represented, the sources of energy that feed it, and the combination of various air currents into more complex patterns, as far as I could tell from some of the videos ASOBO has published.

My main focus goes to gliders and their new functionalities and to rotary wing, but this new "cube" around the aircraft is surely going to be food for my tests.

Presently thermals aren't very consistently modelled, and it's evident from the way you catch them in simulated gliders and the kind of flight path you're able to follow in order to try to stay within their "cone of action", so, I hope this got fine tuned for the upcoming soaring weather in SU11.

But, as a comparison from previous versions of MS SF, WOW!!! that's surely a HUGE step ahead...

Edited November 4, 20223 yr by jcomm

2 hours ago, ThomseN_inc said:

I wonder why it is measured in KM while for everything else NM is the way to go in aviation.

Probably because metric is the norm in science and this is a scientific aspect of flight.

8 minutes ago, jcomm said:

It's been done in X-Plane for some time, I should point out.

You can actually see the vertical components of the airflow around an aircraft in that simulator using the available on-screen output, and X-Plane has modelled since XP10 the deflection of air currents due to orography, as well as wake turbulence, shear and even microbursts.

The difference IMO is that ASOBO is taking a slightly more elaborate approach to the modelling of some of these currents, including the way convection is represented, the sources of energy that feed it, and the combination of various air currents into more complex patterns, as far as I could tell from some of the videos ASOBO has published.

Well... :) to be clear, XP has not done actual CFD using Navier Stokes equations (like https://docs.flightsimulator.com/flighting/html/Developer_Mode/Aircraft_Editor/Debug/Debug_Aircraft_CFD.htm) to model airflow even for the immediate area around an aircraft, let alone a 20km cocoon around it which MSFS is doing in SU11. AKAIK yes XP shows airflow and force vectors around the aircraft as MSFS did from initial release, and yes it does thermals based on orography (i.e. terrain) but so did MSFS from the beginning (this was a simpler modelling of thermals). But now we're talking about atmospheric airflow simulation on a much larger scale here, and various factors feeding into thermals simulation (as listed in prev post), all driven by actual CFD to boot, and how turbulence finally is simulated based on all these airflows interacting/colliding. I'd say it's way more than "slightly" in how elaborate the simulation of atmospheric airflow is in SU11. What MSFS is doing here is an entirely different league quite frankly, IMHO of course.

Hopefully Asobo updates the SDK docs above for this new expanded CFD-based atmospheric airflow simulation, but like I said before this thread on the official forums contains a wealth of info: https://forums.flightsimulator.com/t/testing-the-new-airflow-simulation/549454

Updraft simulation

The updraft simulation simulates rising air - the results of which are fed into the atmospheric airflow simulation. The updraft simulation particles are created close to the ground based on the solar radiation simulation and clouds. Their velocity is based on the solar radiation simulation and wind speed, and their initial angle is based on the terrain. These particles are affected by the wind, but not the terrain or the scenery (after they are created). They rise on an angle relative to the terrain and are blown by the wind. The higher the wind, the less altitude the particle will gain before dying. Right now (SU11 Beta) there is a minimum wind speed of about 3 knots to get proper thermals.

Atmospheric airflow simulation

The atmospheric airflow simulation covers a large area around your plane and is affected by the DEM, live data, and updraft simulation. The upper-altitude of this simulation is the boundary layer. This simulation is always done a small distance above ground level and does not increase in altitude with your plane. Objects and trees do not affect this simulation. Since this simulation has long-lived particles, it can result in interesting behavior, such as tumbling air (rotor turbulence).

Proximity Airflow Simulation

The proximity airflow simulation covers a much smaller distance and the particles have a lower lifespan, but it updates much more frequently and is affected by just about every object in the scene ( including trees and buildings), as well as live data, at a resolution of about a foot. The atmospheric airflow simulation is an input for the proximity airflow simulation until the boundary layer, after which it is just the wind (live data) that affects the proximity airflow simulation.

Updraft simulation → Atmospheric airflow simulation → Proximity airflow simulation → Aircraft
 

Blue = Lateral movement (or deflected)
Green = Rising
Red = Falling

The length of the line represents the speed. The red cube at the end of the line represents the origin of the CFD particle. The colors are blended, so air that is falling on an angle will be purple for instance.

In the first screenshot, the air is being pulled up to the right (teal lines) and the air behind it was tumbling and falling. The airflow CFD particles have a finite lifespan based on the velocity of the particle. As you increase the wind speed you’ll notice that the CFD particles are created further away and travel further.

The general idea is the atmospheric flow simulation creates a backdrop for the proximity airflow simulation. The atmospheric flow simulation only creates particles right above ground level, primarily interacts with the DEM and thermals, and does not increase in altitude with your plane, but since it’s such a large distance, it can simulate things that the proximity airflow can’t, such as eddies. The proximity airflow particles is then pushed along by the atmospheric flow simulation particles and checks for more things along the way (at a resolution of 1ft), such as buildings and trees.
 

As long as my 8 year old CPU can keep up.. 😉