Tesla Model 3 Aerodynamics Explained By Exa’s Digital Simulation Expert

2 years ago by Steven Loveday 52

Tesla Model S Steam Ribbons (via EXA/PFPR Communications)

Tesla Model S Steam Ribbons (via EXA/PFPR Communications)

InsideEVs received an email with an article penned by Exa Corporation’s Digital Imaging Expert, Ales Alajbegovic (via Rupert Andrews/PFPR Communications), explaining the upcoming Tesla Model 3 aerodynamics, and its impact.

Exa’s PowerFLOW digital simulation software is used by Tesla to design its cars. While the Exa corporation doesn’t actually see Tesla’s process, the company uses the same software to analyze the vehicles, and can provide valuable information.

Tesla Model 3, No Front Grille

Tesla Model 3, No Front Grille

In order for the Model 3 to hit its promised base price of $35,000, the battery pack will need to be smaller. This makes achieving the hopeful 215 mile range a challenge. Tesla CEO, Elon Musk said the drag target is set to be extremely low, at 0.21 Cd. This is lower than the Model S that boasts 0.24.

As an example, when Tesla reduced the Model S Cd from 0.32 to 0.24, the range increased by 50 miles. Ales speculates that the 0.21 reduction could add another 10-20 miles of range.

The reveal of the Model 3 showed that the company has gone to great lengths to assure that the goals are met. The first noticeable change is the fact that the Model 3 has no grille or grille graphic. This allows for the continuous wedge shape to aid in air flow. Some people complained about the look of this, but the all-electric car has no need for it.

Ales believes that there are no “active” aero devices on the Model 3; another cost saver. Instead, everything is designed to be aerodynamic in and of its own physical design. For instance, all wheel designs use a “turbine-blade” style that forces air beneath the car, limiting drag.

Since Tesla decided not to switch to cameras yet, the side mirror mounts are thinner and more aerodynamic. Air is forced to flow into the front of the car and over the wheels, due to air curtains in the fenders. This also directs the air flow more smoothly along the sides of the vehicle. Underneath the vehicle has not been seen clearly, but Ales said it is likely to be “flat and smooth” with a diffuser at the rear.

It will be very telling to see the final product and the actual numbers for drag and range. Tesla has never had issues with range in the past, as the company has surpassed all competitors in the category, but keeping the cost down for the Model 3 is something that is new to the company. It’s probably pretty safe to say that Ales of Exa is the authority when it comes to crunching these numbers.

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52 responses to "Tesla Model 3 Aerodynamics Explained By Exa’s Digital Simulation Expert"

  1. sven says:

    “For instance, all wheel designs use a ‘turbine-blade’ style that forces air beneath the car, limiting drag.”

    Interesting. I didn’t know that.

    1. MTN Ranger says:

      I wonder how that compares to the “moon discs” some eco-modders use.

    2. Speculawyer says:

      Yeah, I never heard about that either. I wonder if it is really true.

      If true . . . wow . . . I’m blown away. What a way of discovering a beautiful wheel design that is also engineering functional.

    3. Kdawg says:

      And golf ball pockets are also aerodynamic. Maybe Tesla should go the Mythbusters route.

      1. Pushmi-Pullyu says:

        Aieeee! My eyes! 😉

      2. Dragon says:

        I’d love to see a car like that putt-putting around town.

        1. deborahabc123 says:

          LOL !!!!!!!!!!!!!!!!!!!! 🙂

      3. Brian says:

        That car is probably a FOUUUURRRRRR! banger 😉

    4. mtavel says:

      Something seems fishy with the wheel story. The wheels are all identical…. so while the ‘turbine’ wheels on the left side of the car may be forcing air underneath the car, the wheels on the right would be sucking the air out from underneath the car and out the side. The wheels are flipped from one side to the other, so the turbines force air in opposite directions.

      1. Bone says:

        I agree. While most other things in the article make perfect sense, the part about wheels seems bit off. Maybe the people at Exa are most focused in taking full advantage of having Tesla as a customer and telling a good story to boast their sales.

        Turbine blade wheels were originally used in track cars to improve air flow to cool the brakes. On regular street cars it’s mostly aesthetics. Smooth discs without openings are generally considered best for aerodynamics. Most efficiency oriented wheels are almost flat, but have just small openings to provide some airflow to the brakes.

      2. sven says:

        Holy sh*t, you’re right.

        1. sven says:

          My BS detector must have been malfunctioning.

      3. David S. says:

        Look at the photos more closely. The wheels on the right side and left side seem to be different (symmetrical).

        1. Djoni says:

          You mean asymmetrical, because they’re different on each side.
          Like a mirror image.
          And that photo just might be that.
          But if not it’s just like having a left and right foot.
          If the tire is the same size its good since rotation is usually just moving front and rear wheel of the same side.
          And then, this turbine blowing air would make some sense, although I always thought that less air underneath is more aerodynamic.

        2. Jacked Beanstalk says:

          Nice catch. Those photos show entirely different wheels than the aerodynamic illustration in the article, furthermore they would move air from underneath the car at high forward speeds.

  2. beta995 says:

    I wonder about the bumper shape that directs are down, and not over the hood.

  3. Rob Stark says:

    “Since Tesla decided not to switch to cameras yet”

    More accurately, the Regulators have not allowed Tesla to switch to cameras yet.

    1. Speculawyer says:

      Yeah, I was pretty annoyed by that line as well. I’m sure Tesla is VERY EAGER to dump the side mirrors ASAP. They are just not allowed. That regulation really needs to change. I never even use the passenger side one, that one is useless.

      1. Mxs says:

        Are you serious???? You should not be saying it out loud, really.

        But I guess I am not completely surprised. The way driving is trained and licensed in North America, this market will greatly benefit from autonomous cars …. The lawyers, just need to figure out who they will litigate with …. The car company, the hardware supplier or the programmer??

        1. evcarnut says:

          The Lawyers can litigate in Hell with themselves & get Real Jobs! Shovelling Coal for the Deviall.. l o l ….

          1. Nick says:

            Haha!

            That’s funny.

        2. Jim says:

          For people that actually turn their head, seeing to the side of the car and behind is not a problem. The mirror is not used. For the lazy people that can’t turn their head, yes they need a mirror … and blind spot detection, since you can’t see it with the mirror and you didn’t bother physically looking there.

          That being said, replacing the mirrors can provide better visibility, and will be welcomed.

          1. super390 says:

            I need that passenger side mirror. My Ford has a big blind spot, I don’t wear contacts and when I’m going 40 mph on a winding road along a bayou I can’t spend a lot of time trying to look over my shoulder.

            1. Jim says:

              A “shoulder check” is considered proper driving. Don’t admit you don’t do it. People that don’t follow proper driving for whatever reason, gives reasons for those that want autonomous to fully take over eliminating the driver completely.

      2. Jacked Beanstalk says:

        “I never even use the passenger side one, that one is useless.”

        And they should lose those stupid turn signals that nobody uses!

  4. HVACman says:

    “This allows for the continuous wedge shape to aid in air flow. Some people complained about the look of this, but the all-electric car has no need for it.”

    This is “kinda” true, but it ain’t that simple. There is still the need for SOME air (about 2,500 cfm) to flow through the front of the vehicle, as the front is where the air-cooled AC condenser coil, Battery TMS cooling coil, and drive unit/power electronics cooling coil are located. There can be up to 50,000 BTU/hr of heat to be dissipated. Not the 600,000 BTU/hr that an ICE has to remove, but still….you have to have some air moving through there, either via ram effect of with fans pulling air from shutters.

    1. evcarnut says:

      I owned a Studebaker AVANTI …it had “no grill opening” way back then …just a Small slit at the bottom ..with the Rad Inside on a Angle to catch the air & keep the engine Cool…It looked odd especially back then ., But I liked it .They always said Avanti body design was Ahead of it’s time …Way ahead , except for the ICE engine …Just Google “Studebaker Avanti Cars ” & See…….

      1. evcarnut says:

        BTW….Avanti was designed in 1963 by a Frenchman That designed & Invented the Ball Point Pen …The Avanti Still Looks great …, Even today!..”N0 GRILL”..Check it out!

        1. sven says:

          It would look better with a nose cone. 😉

      2. super390 says:

        Its cD, I think, was in the low .30 range. It was good enough that Avantis set some class speed records at Bonneville despite the limitations of Studebaker’s small-block V-8. The supercharged Avantis that set those records were sold in tiny numbers and must be very valuable now.

  5. SparkEV says:

    Model S 0.24 is 75% of 0.32.

    Model 3 0.21 is 88% of 0.24.

    Model 3 is smaller than S. How much smaller frontal area isn’t known, but if one guesstimates 88% of S, then 3 would be about 75% of S aerodynamically, same as going from 0.32 to 0.24.

    If S got 50 miles bump from 25% better aero, I would expect 3 to get similar bump. How is it then it’s only 10-20 miles? Does he mean only with regard to Cd and not frontal area?

  6. Speculawyer says:

    I say it over and over . . . this is why Tesla is the only company that really gets EVs done right.

    Engineering matters.

    An insideEVs thread about a good article by Car & Driver on aerodynamics:
    http://insideevs.com/car-driver-aero-comparo-tesla-model-s-versus-volt-leaf-prius-video/

    1. Mxs says:

      And you somehow think that the other car companies do not know these things??? They all have massive experiences in racing, these teams live in wind tunnels ….

      Don’t make something from Tesla what it is not. They have a clean slate and are you using modern technology to create BEV vehicle …. Which desn’t mean that they are the only ones. The oil baggage is important distinction …. Not a low drag know how ….

      1. Nick says:

        Unable vs unwilling isn’t a super useful distinction.

        1. Mr. M says:

          Mercedes produces cars with cd = 0,21 – 0,24 since ages.

      2. Pushmi-Pullyu says:

        No, I do not think the other car makers know how to properly design a car to be useful, stylish, and have very low wind resistance. Just because they have the aeronautical equations, doesn’t mean they have the ability to marry the needs of very low drag to the kind of car that people find useful and attractive.

        Look at the VW XL1, for example. That is a case of extreme engineering for low drag. To accomplish that, VW put the rear wheels closer together than the front wheels, used rear wheel skirts, and even went to the extreme of offsetting the passenger’s seat from the driver’s seat, so much so that the driver can’t even carry on a normal conversation with his passenger.

        Before the Model ≡ Reveal, there was speculation in comments here on InsideEVs that Tesla might have to put rear wheel skirts on the car to attain their goal of very low drag. That Tesla accomplished its goal without making it a weirdmobile like the XL1, and without even using wheel skirts, is a testament to the ability of Tesla’s engineers and designers.

        You think Tesla cheerleaders are over-praising the company? In certain respects they are. But in this particular area, I think Tesla deserves even more praise than it’s getting.

        1. super390 says:

          Tesla said .21 was the goal, not what the running prototype actually attained. There may still be minor changes coming that some people will call ugly. I’m fine with this, though, because I don’t think anyone’s being serious until they’ve gone under .20.

          I don’t think the Ford Probe V (0.137) is weird except for its wheel skirts and doors.

          http://www.carstyling.ru/en/car/1985_ford_probe_v/

          It was claimed to do that despite having intakes and an exhaust system. An EV version could do better.

          1. Speculawyer says:

            That’s a tall order. That gets into weirdmobile territory. Now I would still buy such a car. I wanted the Aptera. But going so weird moves the vehicle out of mass market acceptence in today’s world. You have to move forward slowly to allow people to become move accepting of such designs.

            I realize now, that “aerodynamic beyond consumer acceptance” is what Elon meant when he said ‘weirdmobile’

        2. Mr. M says:

          As far as i know the Mercedes CLA has also a cd of 0,21. To me it looks pretty normal.

      3. Speculawyer says:

        I didn’t say they don’t know these things. That’s irrelevant. They are not DOING these things.

    2. evcarnut says:

      The big difference between the big auto cartel & Tesla is that Tesla cars are Compelling , UNLIKE the COMPLIANCE Sh!t Boxes that The Big auto Cartels Build………….

  7. kdawg says:

    I wonder if they explain why black is always the fastest color?

    1. Jay Cole says:

      Well, that seems pretty /obv

    2. Speculawyer says:

      It absorbs extra energy from the sun to power it along.

    3. Koenigsegg says:

      Because Batman

    4. Pushmi-Pullyu says:

      Well, obviously black absorbs more sunlight, making the “skin” of the car hotter, and the extra heat radiating away from the surface creates microturbulances in the air right next to the surface. As we all know, microturbulances make an aerodynamic shape “slipperier”, allowing air to flow over it with reduced drag. This, therefore, increases the black car’s speed. 😀

      “If you can’t dazzle them with brilliance, baffle them with B.S.” — W.C. Fields

  8. Heisenberghtbacktotheroots says:

    Thanks Steven for one of the most interesting articles about the model 3 I have read so far.

    And thanks to all commenters for adding even more value!

  9. koz says:

    Looks to me from some angles that Tesla has taken a aero cue from the Leaf’s headlights. Model 3’s headlights are no where near as pronounced as the Leaf’s but they are more so than the S’. This helps lower the drag from the side view mirrors.

  10. Nix says:

    This is why all of those M3 front end photoshop nose-jobs are pointless. They aren’t going to change the shape just for looks. At most the M3 might get some minimal trim pieces on the nose as part of phase 2.

    The guy planning on selling fake grill wraps out of car wrap material probably has it right. The nose is what it is (which I’m perfectly fine with.)

    1. Pushmi-Pullyu says:

      Nix said:

      “They aren’t going to change the shape just for looks. At most the M3 might get some minimal trim pieces on the nose as part of phase 2.”

      I’m pretty sure you’re right. I don’t like the “shark’s nose” shape, but I have no doubt there is an excellent aerodynamic reason Tesla engineers chose that shape, and they’re not gonna change that just to make the car a bit more stylish.

      The “shark’s nose” is a triumph of practicality over style.

  11. Al S says:

    The wheels on the prototypes are 20″. Wouldn’t 17″-18″ ones be more efficient?

    1. Speculawyer says:

      The base model probably will have smaller and more boring steel rims.