What does a drag coefficient of 1 mean?
The Reynolds number will be low for small objects, low velocities, and high viscosity fluids. A equal to 1 would be obtained in a case where all of the fluid approaching the object is brought to rest, building up stagnation pressure over the whole front surface.
Can coefficient of drag be greater than 1?
The drag coefficient of a vehicle is affected by the shape of body of the vehicle. Can coefficient of drag be greater than 1? It’s only approximately constant. For example the drag coefficient of a sphere can vary depending on the speed and can have values greater than 1 at low Reynolds numbers.
What’s the most aerodynamic shape?
For speeds lower than the speed of sound, the most aerodynamically efficient shape is the teardrop. The teardrop has a rounded nose that tapers as it moves backward, forming a narrow, yet rounded tail, which gradually brings the air around the object back together instead of creating eddy currents.
Is drag coefficient constant?
For most aerodynamic objects, the drag coefficient has a nearly constant value across a large range of Reynolds numbers. In all of the cases presented on this figure, the density, viscosity, and diameter of the ball are the same. The flow velocity is gradually increased from the left to increase the Reynolds number.
Does drag increase with speed?
Drag increases with speed (v). An object that is stationary with respect to the fluid will certainly not experience any drag force. Start moving and a resistive force will arise. Get moving faster and surely the resistive force will be greater.
What is a normal Reynolds number?
Actually, the transition between laminar and turbulent flow occurs not at a specific value of the Reynolds number but in a range usually beginning between 1,000 to 2,000 and extending upward to between 3,000 and 5,000. …
What is a good Reynolds number?
We can determine whether fluid flow is laminar or turbulent based on the Reynolds number. If the Reynolds number is less than 2300, the flow is laminar. Any Reynolds number over 4000 indicates turbulent flow.
What is Reynolds number equal to?
Reynolds number (Rn) is defined as Rn=(ρVL)/μ=(VL)/ν, where V is the fluid velocity relative to the body and L is a typical length.
What is the value of Reynolds number for turbulent flow?
2000
What is H in Nusselt number?
Forced convection in fully developed laminar pipe flow For fully developed internal laminar flow, the Nusselt numbers tend towards a constant value for long pipes. For internal Flow: where: Dh = Hydraulic diameter. kf = thermal conductivity of the fluid.