Calculating Force of Drag Using the Reynolds Number

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The discussion centers on calculating the force of drag (Fd) using the Reynolds number, which is defined as the ratio of inertial forces to viscous forces. Participants debate the relationship between Fd and the Reynolds number, questioning whether Fd should be equated solely to inertial forces or if it should also include viscous forces. Clarifications are sought regarding the influence of air viscosity on drag and the transition between turbulent and laminar flow regimes. References to external resources, including NASA and Wikipedia, are made to support claims and seek further understanding. The conversation highlights the complexity of drag calculations and the need for clearer explanations in existing literature.
luckis11
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See

http://en.wikipedia.org/wiki/Drag_(physics )

There are two regimes, turbulent (high Reynold's number) and linear (Stokes) drag.

Bob S
 
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I meant how Fd is related to:

(Reynolds Number)=(Inertial Forces)/(Viscous Forces)
 


luckis11 said:
I meant how Fd is related to:

(Reynolds Number)=(Inertial Forces)/(Viscous Forces)

Did you not read the link I gave you?

...For the gas, the magnitude depends on the viscosity of the air and the relative magnitude of the viscous forces to the motion of the flow, expressed as the Reynolds number...

CS
 


"...For the gas, the magnitude depends on the viscosity of the air and the relative magnitude of the viscous forces to the motion of the flow, expressed as the Reynolds number..."

So? We have:
Re=(inertial forces)/(viscous forces)

At wiki it says
" Note that this (Re) is equal to the ratio between...which is the drag (up to a numerical factor, half the drag coefficient)..."

So, Fd=(inertial forces)?
Should't it be Fd=(inertial forces)+(viscous forces)?

Both wrong? Any site making all this a bit clear?
 
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