1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Fluid Mechanics - Drag coefficient and Pressure coefficient

  1. Jun 26, 2008 #1
    Hey guys,
    I'm working on a lab here about pressure variation normal to streamlines. For the last experiment, there is airflow around a cylinder with a static pressure tap. The pressure tap records Cp (divides by dynamic pressure) and angle of rotation.

    I have data points for Cp vs Theta (10° increments) that looks great, just like it should. Now I need to calculate Cd. After looking on the web a lot I found something that said

    Cd=.5*INT(Cp*cos(x) dx, 0, 360(or 2pi))

    I have computed this integral as an area under the curve both in Excel as Riemmen Sums and with a fit line on my calculator. Both ways I get answers around 30. I thought I was fine...

    Now I have a lab due tomorrow and found out Cd should be more like 1.1 or so. Any ideas? Is there another relationship between Cp and Cd?
  2. jcsd
  3. Jun 26, 2008 #2
    The expression for drag coefficient looks good. What are your (theta, Cp) values?

    Chusslove Illich (Часлав Илић)
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?