Profile Drag Coefficient

[dtoshni]

I am in a fix. Can a body have two different drag coefficients for forward and backward motion? Because, I was investigationg the case of this diving vehicle and throufh my calculation I ended up getting Cd = 0.39 and 0.86 for upward and downward motion respectively(ie keeping the profiler aligned in +z direction, two different Cd for motion along +z and -z). Is it normal or am I doing something wrong?

Thank you

Daniel T

[Guest625101138]

Yes. Anemometers rely on this principle.

Not sure about your example though. You would need to explain more about what you are doing.

Rick W.

[dtoshni]

Thank you Rick.

I was investigating the case of this vehicle, a profiler(autonomous) that goes down with the help of a thruster and when it has to come up it comes up due to its positive buoyancy, It essentially travels in one dimension only. and it points towards downward direction only.

Daniel

[Guest625101138]

There are some common shapes shown midway down this page with
http://www.aerospaceweb.org/question...cs/q0231.shtml

A good example is the half sphere. This is the typical cup on an anemometer. The difference in Cd is substantial.

Rick W.

[dtoshni]

Thanks a lot Rick!! The link helped a lot.