- #1
PhyIsOhSoHard
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As you can see, around Reynolds number of 5 105 the transition occurs for a smooth sphere.
However, why is it that after this transition that the drag coefficient increases at turbulence?
[Aerodynamics] Why does the drag coefficient increase after turbulence
- Thread starter PhyIsOhSoHard
- Start date
In summary, the drag coefficient is a dimensionless quantity that represents the resistance an object experiences as it moves through a fluid. It is calculated by dividing the drag force by the product of the dynamic pressure and the frontal area of the object. Turbulence affects the drag coefficient by creating areas of high and low pressure, resulting in a higher drag force. However, it is possible to reduce the drag coefficient after turbulence by designing the object with aerodynamic shapes and implementing control systems. An increase in drag coefficient can negatively impact an object's performance by reducing speed and increasing energy consumption, making it crucial to minimize drag in industries such as aviation and automotive.
As you can see, around Reynolds number of 5 105 the transition occurs for a smooth sphere.
However, why is it that after this transition that the drag coefficient increases at turbulence?
- #2
rcgldr
Homework Helper
- 8,855
- 632
A lot of the drag for a sphere is related to the size of the wake induced behind the sphere. The drop in the curves corresponds to the air tending to stay attached longer to the surface of the sphere, reducing the size of the induced wake, and decreasing coefficient of drag. As the speed continues to increase, the wake starts to increase in size again.
1. What is the drag coefficient?
The drag coefficient is a dimensionless quantity that represents the resistance an object experiences as it moves through a fluid, such as air. It is dependent on the shape and size of the object, as well as the properties of the fluid.
2. How is the drag coefficient calculated?
The drag coefficient is calculated by dividing the drag force (the force that opposes the motion of the object) by the product of the dynamic pressure (a measure of the fluid's density and the object's velocity) and the frontal area of the object. This calculation is typically done through experimentation and can vary depending on the conditions of the experiment.
3. Why does turbulence affect the drag coefficient?
Turbulence is caused by chaotic fluctuations in the fluid's velocity, which can create areas of high and low pressure around the object. This changes the flow of the fluid around the object and can increase the drag force, resulting in a higher drag coefficient.
4. Can the drag coefficient be reduced after turbulence?
It is possible to reduce the drag coefficient after turbulence by designing the object with aerodynamic shapes and smooth surfaces that minimize the creation of turbulence. This can also be achieved by implementing control systems, such as active flow control, to manipulate the fluid flow and reduce turbulence.
5. How does the increase in drag coefficient affect an object's performance?
The increase in drag coefficient can negatively impact an object's performance by reducing its speed and increasing the amount of energy needed to overcome the drag force. This can be especially detrimental in industries such as aviation and automotive, where reducing drag is crucial for optimal performance and efficiency.
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