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TESLA CYBERTRUCK AERODYNAMICS | CFD simulation with Pacefish



How aerodynamic is the Tesla CYBERTRUCK? How does its unusual SUV design influence the aerodynamics? At Numeric Systems GmbH we had the same curiosity, so we decided to perform a simulation of the CYBERTRUCK using our CFD simulation software Pacefish.

For that, we used an adapted publicly available geometry (https://grabcad.com/library/tesla-cybertruck-18). This non-official Tesla geometry may not be accurate on the details nor include the latest modifications of the car, but it should be suitable to see how this design performs aerodynamically on its whole.

WE OBTAINED A DRAG COEFFICIENT OF 0.39. 🧐 For comparison, this value is almost double of the model S (Cd = 0.208*), higher than the speculated for the BMW iX (Cd = ~0.25**) or the 2020 Ram 1500 (Cd = 0.357***), but substantially lower than the speculated for the F150 lightning (Cd = ~0.56**). In terms of range compared to the model S, at high speeds the CYBERTRUCK is expected to lose range more than two times faster due to its bigger frontal area.

⚡️POSITIVE SURPRISE⚡️
Contrary to what many people would think, the sharp edge of the roof does not produce a big detachment! 🤯 It is true that the flow it is not attached, but in fact the air follows down the slope quite seamlessly. The boundary layer does not substantially grow. This is quite remarkable and a big aerodynamic advantage compared to other pick-up trucks. Moreover, the diffuser makes a substantial effect in the center of the vehicle’s rear-end! It creates suction and reduces the wake.

⚡️IMPROVEMENT POTENTIAL⚡️
On the other side, our results show clear turbulent structures created by the front edge which connects the bumper and the bonnet, the vertical edge right behind the front lights, the wheel arches’ “protectors”/surrounding edgy geometry, the rim styling and the geometry of the a-pillar and c-pillar. 🤔 The generation of the turbulent structures is caused by the sharpness of these edges. These geometrical features increase the drag of the vehicle, which ultimately reduce the range the CYBERTRUCK. Furthermore, due to the sharp rear end, the flow instantly detaches and creates a considerably big low energy area (wake), mostly noticeable behind the top and side rear-end edges.

⚡️SUMMARY⚡️
Seems like having a head-turning design does NOT come at a high price for the aerodynamic performance of the CYBERTRUCK. 👏 The sloped geometry of the windshield and the bed cover make a very good job of keeping the air attached to the car, thus lowering the drag. It is a smart design. 🤓 At the same time, by adjusting couple surface features, in particular the surrounding edgy geometry of the wheel arches, the drag could be lowered even further. This reflects the typical conflict of interests between design and aerodynamic efficiency in the automotive industry.

⚡️SIMULATION APPROACH⚡️
Pacefish is our in-house GPU-accelerated Lattice Boltzmann Method (LBM)-based CFD software. For this setup we used the SST-DDES turbulence model, our proprietary wall model, moving ground and rotating tires (but not rims, due to current limitations), a simulation velocity of 100 km/h (62 mph) and the smallest element size of 2.89 mm. Due to the inherently transient definition of LBM, we performed a transient analysis and a statistical one, derived using time averaging. Pacefish uses a structured mesh that robustly handles challenging details of the geometry like sharp edges, so the mesh generation is fast and its setup straight-forward requiring minimal to zero model cleanup. We used 148 million cells for this simulation, which covered 6.4 seconds of physical real time. The run took 45h wall clock time on two GPUs which is a considerably short amount of time for such large transient setup. The production costs of this simulation run are below 1000€.

⬇️ ⬇️ Share here your questions and comments regarding this CYBERTRUCK simulation. ⬇️ ⬇️
Learn more about Numeric Systems GmbH or Pacefish on our website https://www.numeric.systems/ . Stay tunned to Numeric Systems GmbH on LinkedIn by following https://www.linkedin.com/company/numeric-systems-gmbh/ . Get in touch with us by e-mail via [email protected] and [email protected]
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Geometry: The base stl is from GrabCad https://grabcad.com/library/tesla-cybertruck-18 (thanks to Nicola Perna for that). In addition, we modified the tires, closed some big gaps inside the rear wheel arches and adjusted the diffuser’s geometry, so it resembles more to the actual shape of the CYBERTRUCK.

* https://www.tesla.com/models
** https://www.myevreview.com/
*** https://aeceurope.com/2020-ram-1500-capability/

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Stay tunned to Numeric Systems GmbH on LinkedIn by following https://www.linkedin.com/company/numeric-systems-gmbh/ . Get in touch with us by e-mail via [email protected] and aleix.la[email protected]

Original post: https://www.linkedin.com/feed/update/urn:li:activity:6953662440844759040/