Coefficient of Drag of a projectile for different Mach Numbers

CdProjectile · January 12, 2018, 12:09

Hi guys,

I am in need of some help with a simulation. I am looking to do a simulation to find the coefficient of drag around a 155mm projectile for multiple Mach Numbers. I am approaching this as a 2D simulation. Currently any value I get for CD is blatantly wrong (in the thousands but should obviously be below 1). For low velocities of around 3 m/s the result would appear correct although obviously projectile travel much faster than this. At high velocities the result i get is in the millions so is obviously not correct.

ANyone have any ideas that can help me in my problem.

I have been following an adapting these two tutorials as i go along in the hope of getting things correct:

https://confluence.cornell.edu/displ...+Physics+Setup

https://confluence.cornell.edu/displ...+-+Step+4+*New

I also hope to get a illustration of the pressure around the projectile that shows how the pressure at the back of the projectile is lower due to the fact it is a blunt body.

Thanks.

DEd · January 12, 2018, 15:52

In order for the Cd to be correct you need to specify the right reference values.

CdProjectile · January 12, 2018, 16:50

Quote:

Originally Posted by DEd

In order for the Cd to be correct you need to specify the right reference values.

What values are you talking about and where do i go to change them. Using ansys 18.2 currently

DEd · January 12, 2018, 17:17

The "Reference values" in the tree view. Can also be found under the tab "Setting up physics" and "Reference values"

January 12, 2018, 12:09	Coefficient of Drag of a projectile for different Mach Numbers	#1
CdProjectile New Member Join Date: Dec 2017 Posts: 5 Rep Power: 8	Hi guys, I am in need of some help with a simulation. I am looking to do a simulation to find the coefficient of drag around a 155mm projectile for multiple Mach Numbers. I am approaching this as a 2D simulation. Currently any value I get for CD is blatantly wrong (in the thousands but should obviously be below 1). For low velocities of around 3 m/s the result would appear correct although obviously projectile travel much faster than this. At high velocities the result i get is in the millions so is obviously not correct. ANyone have any ideas that can help me in my problem. I have been following an adapting these two tutorials as i go along in the hope of getting things correct: https://confluence.cornell.edu/displ...+Physics+Setup https://confluence.cornell.edu/displ...+-+Step+4+*New I also hope to get a illustration of the pressure around the projectile that shows how the pressure at the back of the projectile is lower due to the fact it is a blunt body. Thanks.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
wrong SU2 calculation for lift and drag coefficient for NAC4421	mechy	SU2	7	January 9, 2017 05:18
Drag Coefficient for Ellipse Form (2D)	Ketut Utama	Main CFD Forum	8	December 11, 2014 11:03
Strange values in drag coefficient of a fuselage	Victor31	FLUENT	5	May 14, 2014 11:30
problem with saving drag coefficient	colopolo	FLUENT	5	April 12, 2013 10:59
Plot drag coefficient against Y(distance)	edwin	FLUENT	0	February 4, 2008 09:41

January 12, 2018, 15:52		#2
DEd Member Daniel Edebro Join Date: Feb 2016 Location: Gothenburg Posts: 41 Rep Power: 10	In order for the Cd to be correct you need to specify the right reference values.

January 12, 2018, 17:17		#4
DEd Member Daniel Edebro Join Date: Feb 2016 Location: Gothenburg Posts: 41 Rep Power: 10	The "Reference values" in the tree view. Can also be found under the tab "Setting up physics" and "Reference values"