What is reference area for drag?

What is reference area for drag?

The reference area depends on what type of drag coefficient is being measured. For automobiles and many other objects, the reference area is the projected frontal area of the vehicle. This may not necessarily be the cross sectional area of the vehicle, depending on where the cross section is taken.

How is drag coefficient calculated?

The drag coefficient Cd is equal to the drag D divided by the quantity: density r times half the velocity V squared times the reference area A. The drag coefficient then expresses the ratio of the drag force to the force produced by the dynamic pressure times the area.

What are the dimensions of the drag coefficient?

What is the dimension for drag coefficient? Explanation: In fluid dynamics, the drag coefficient has no dimensions. It is a dimensionless quantity. Drag coefficient is used to quantify the resistance of an object in a fluid environment.

Does drag coefficient have units?

The units below are consistent units for the drag force equation. A = Reference area as (see figures below), m2. C = Drag coefficient (see figures below), unitless.

What is dimension for drag coefficient?

Explanation: In fluid dynamics, the drag coefficient has no dimensions. It is a dimensionless quantity. Drag coefficient is used to quantify the resistance of an object in a fluid environment. It is mainly used in air and water.

How does area affect drag coefficient?

The total aerodynamic force is equal to the pressure times the surface area around the body. Drag is the component of this force along the flight direction. Like the other aerodynamic force, lift, the drag is directly proportional to the area of the object. Doubling the area doubles the drag.

How do you find drag coefficient from Reynolds number?

Figure 1 graphs the dependence of drag coefficient for a sphere and a cylinder in crossflow on the Reynolds Number Re = ρuD/η, where D is the sphere (cylinder) diameter, η the viscosity of liquid, and .

How do you find the frontal area?

Question: The frontal area A represents the frontal projection of the car’s area and could be approximated simply by multiplying 0.85 times the width and the height of a rectangle that outlines the front of a car. This is the area that you see when you view the car from a direction normal to the front grills.

What is drag coefficient measured in?

Variable Identity Metric Units
D Drag Newtons
Cd Drag Coefficient No units
r Density of air kg/m3
V Velocity m/s

Does drag coefficient have a unit?

Its a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water. It is used in the drag equation in which a lower drag coefficient indicates the object will have less aerodynamic or hydrodynamic drag.

What is the drag coefficient of a cylinder with L/D 0?

It is therefore not surprising that the drag coefficient for a cylinder with l/d=0 is about 1.17, the same as a flat disk. The reference area for a cylinder is also the same as that used for the disk except the radius is that of the cylinder’s circular cross-section.

What is the drag coefficient of a circular disk?

Above a Reynolds number of 1000, the drag coefficient of the circular disk becomes a constant that has been consistently measured as 1.17. This coefficient is based upon a reference area equal to the frontal area of the disk, or π r² where r is the radius of the disk.

What area should be used to calculate drag?

What area to use depends upon the application. In case of a cylinder it is the projected area normal to flow. For a flow past a thin flat plate, it will be the area of plate exposed to flow. The relative importance of the two kinds of drag is very apparent in case of flow over a circular cylinder or a sphere.

What is the drag coefficient of a cylinder in wind tunnel?

If a cylinder is mounted in this orientation in a wind tunnel, the drag coefficient should be about 1.17 using the same circular reference area assumed for all the shapes we have discussed.