Center of Pressure on a body

jpc · December 1, 2011, 15:54

ok i see where you're going. for those that might be following, here's where blackjack is pointing me (i think)

Mz,cp = Mz,o + (o-cp)xFo
= 17 + (0-0.28,0-0.016)x(-3.48,60.65)
=0.07368Nm

blackjack, how were you able to get yours down to 1 microNm?

would you expect the results of Cp to be the same if the moment was measured from another location?

jpc · December 5, 2011, 18:37

hi, just checking in since removing that spam from the thread. any comments blackjack or others?

blackjack · December 5, 2011, 22:23

rounding-off x by .001 changes the moment by 0.060 Nm.

32-bit precision works for me.

If I stand just right on the bathroom scale, I can have dessert. Likewise, if the forces are measured at a different location, they won't be the same. Hence the CP location will change.

I also envision someone constraining y=0 for an airfoil near zero lift. GIGO.

The less tolerance you have for slop, the less sloppy you can be. It's late. G'day.

Ashish V · February 9, 2021, 02:43

Hi CFDers!!
i am using star ccm+ for simulating my Aerodynamics on car.
but i could not find a proper way to find the Cop of my car.
Can someone tell me how to find the Cop.

Thanks.

February 9, 2021, 02:43	Help needed for finding Cop	#24
Ashish V New Member Ashish Join Date: Feb 2021 Posts: 2 Rep Power: 0	Hi CFDers!! i am using star ccm+ for simulating my Aerodynamics on car. but i could not find a proper way to find the Cop of my car. Can someone tell me how to find the Cop. Thanks.

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December 1, 2011, 15:54		#21
jpc Member JPConway Join Date: Nov 2011 Posts: 33 Rep Power: 15	ok i see where you're going. for those that might be following, here's where blackjack is pointing me (i think) Mz,cp = Mz,o + (o-cp)xFo = 17 + (0-0.28,0-0.016)x(-3.48,60.65) =0.07368Nm blackjack, how were you able to get yours down to 1 microNm? would you expect the results of Cp to be the same if the moment was measured from another location?

December 5, 2011, 18:37		#22
jpc Member JPConway Join Date: Nov 2011 Posts: 33 Rep Power: 15	hi, just checking in since removing that spam from the thread. any comments blackjack or others?

December 5, 2011, 22:23		#23
blackjack Member james nathman Join Date: May 2011 Posts: 62 Rep Power: 15	rounding-off x by .001 changes the moment by 0.060 Nm. 32-bit precision works for me. If I stand just right on the bathroom scale, I can have dessert. Likewise, if the forces are measured at a different location, they won't be the same. Hence the CP location will change. I also envision someone constraining y=0 for an airfoil near zero lift. GIGO. The less tolerance you have for slop, the less sloppy you can be. It's late. G'day.