How is drag coefficient related to Reynolds number?

How is drag coefficient related to Reynolds number?

Note that the drag coefficient decreases with the Reynolds number, and it becomes almost a constant (CD = 0.4) for a Reynolds number between 103 and 2×105. As the Reynolds number increases (Re > 2×105), the boundary layer becomes thinner in the front of the sphere and begins its transition to turbulent.

Is a .3 drag coefficient good?

The average modern automobile achieves a drag coefficient of between 0.25 and 0.3.

What car has the least drag coefficient?

But according to Mercedes, the new A-Class sedan features the lowest drag of any production vehicle in the world, with a coefficient of 0.22. At this level, it defends the world record held by the Mercedes-Benz CLA. Meanwhile, the A-Class hatch is just slightly less impressive at 0.25.

What car has the highest coefficient of drag?

electric Mercedes EQS
The electric Mercedes EQS is the world’s most aerodynamic production car. Its 0.20 drag coefficient beats the Tesla Model S and Lucid Air.

Is Reynolds number same as drag coefficient?

As the Reynolds number is increased, the form drag increases relative to the skin fric- tion. Beyond a Reynolds number of 1000, the skin friction is negligible. Between Re = 1000 and Re = 200000, the point of separation remains very near the equator so the drag coefficient remains approximately constant at CD = 0.4.

When Reynolds number is less than 1 then drag force is?

(iv) If the Reynolds number is very small, much less than 1, then the fluid will exhibit Stokes, or creeping, flow, where the viscous forces of the fluid dominate the inertial forces.

What is the best drag coefficient?

With a drag coefficient of 0.20, Mercedes-Benz claims its upcoming luxury electric car, the EQS, is the world’s most aerodynamically efficient production car.

What is the drag coefficient of a F1 car?

Due to the nature of the vehicles, the aerodynamics of F1 cars are quite different to that of road cars – with drag coefficients of between 0.7 and 1.0 (it used to be even higher but rules restrict how much area can be used for aerodynamic devices) – this is between about 2 and 4 times as much as a good modern road car …

What car has the best aerodynamics?

The Most Aerodynamic Cars You Can Buy

  • Mercedes-Benz A-Class.
  • Mercedes-Benz CLA.
  • Mercedes-Benz S-Class Saloon.
  • Toyota Prius.
  • Hyundai Ioniq.
  • BMW 7 series L.
  • Tesla Model X.
  • Kia Optima Hybrid.

Which EV has the best drag coefficient?

Tesla claims the new Model S Plaid, which can reach 60 mph in under two seconds, is the most aerodynamically efficient production car on the market, with a 0.208 drag coefficient.

Does drag increase with Reynolds number?

As the Reynolds number increases, the viscous forces decrease relative to the inertial forces (and therefore relative to the pressure gradient), so the point of separation moves upstream, towards the equator. As the Reynolds number is increased, the form drag increases relative to the skin fric- tion.

Can you have a negative Reynolds number?

Reynolds number can not be negative in any case because its dimension less number and its shows only magnitude. Re can not be negative, you must use the absolute value of the velocity to obtain it. Re is the ratio of inertia forces to viscous forces , so negative makes no sense.

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