CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > Siemens > STAR-CCM+

new to CFD, changing angle of attack/incidence?

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   April 22, 2012, 11:57
Default new to CFD, changing angle of attack/incidence?
  #1
New Member
 
Benjamin Kim
Join Date: Apr 2012
Location: Philadelphia, Pennsylvania
Posts: 6
Rep Power: 13
bjk87 is on a distinguished road
I am new to CFD and just learning how to use Star-CCM+. I was able to analyze and simulate a very simple airfoil by following tutorials. However, I do not know how to change the angle of attack. Do I just transform the geometry part by rotating it a certain amount of degrees/radians? Or is it more complex than that? Thank you.
bjk87 is offline   Reply With Quote

Old   April 22, 2012, 17:19
Default
  #2
Senior Member
 
Ryne Whitehill
Join Date: Aug 2009
Posts: 312
Rep Power: 18
rwryne is on a distinguished road
Quote:
Originally Posted by bjk87 View Post
I am new to CFD and just learning how to use Star-CCM+. I was able to analyze and simulate a very simple airfoil by following tutorials. However, I do not know how to change the angle of attack. Do I just transform the geometry part by rotating it a certain amount of degrees/radians? Or is it more complex than that? Thank you.

Depending on your problem type, you do not need to rotate the geometry.... just change your farfield boundary conditions to reflect new velocity values (i.e. use the directional scalars of the velocity vector to "rotate" the flow)
rwryne is offline   Reply With Quote

Old   April 23, 2012, 16:42
Default
  #3
Senior Member
 
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,649
Rep Power: 65
LuckyTran has a spectacular aura aboutLuckyTran has a spectacular aura aboutLuckyTran has a spectacular aura about
Quote:
Originally Posted by bjk87 View Post
I am new to CFD and just learning how to use Star-CCM+. I was able to analyze and simulate a very simple airfoil by following tutorials. However, I do not know how to change the angle of attack. Do I just transform the geometry part by rotating it a certain amount of degrees/radians? Or is it more complex than that? Thank you.
It depends on your boundary conditions, but another way is to simply have the velocity inlet to have flow at an angle relative to the inlet instead of purely normal.
LuckyTran is online now   Reply With Quote

Old   April 23, 2012, 18:05
Default
  #4
New Member
 
Benjamin Kim
Join Date: Apr 2012
Location: Philadelphia, Pennsylvania
Posts: 6
Rep Power: 13
bjk87 is on a distinguished road
Oh, I see. Thanks.
bjk87 is offline   Reply With Quote

Old   August 18, 2015, 17:13
Default angle of attack in STARCCM+
  #5
New Member
 
rangel
Join Date: Aug 2015
Posts: 1
Rep Power: 0
rangelgeja is on a distinguished road
Hello all,

I changed the velocity components to obtain an angle in an airfoil but I am having negative drag. Anyone knows why? The lift is ok.

In other simulation, I changed the angle of attack in CAD program and imported for STARCCM+, thus I know the right values. I just would like to be able to change the angle of attack IN the STARCCM.

And you know other ways to do this? I couldn't understand the ways in the tutorial.
rangelgeja is offline   Reply With Quote

Old   August 19, 2015, 13:34
Default
  #6
Senior Member
 
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,649
Rep Power: 65
LuckyTran has a spectacular aura aboutLuckyTran has a spectacular aura aboutLuckyTran has a spectacular aura about
Quote:
Originally Posted by rangelgeja View Post
Hello all,

I changed the velocity components to obtain an angle in an airfoil but I am having negative drag.
Did you update the direction vector for the drag and lift?
LuckyTran is online now   Reply With Quote

Old   August 20, 2015, 16:42
Default
  #7
Senior Member
 
Matt
Join Date: Aug 2014
Posts: 947
Rep Power: 17
fluid23 is on a distinguished road
1. As LuckyTran implied but did not specify, your drag vector must point in the same direction as freestream flow. Lift is perpendicular to that. So if you are changing your velocity vector then your force vectors must change too. You can also define the vectors along the chord line and normal to the chord line to get normal and axial force, then simply transform those using: L=N*cos(AOA)-A*sin(AOA), and D=N*sin(AOA)+A*cos(AOA).

2. No need to rotate in CAD if you want to move model WRT flow direction. There is a transform and rotate function if you right click the geometry under parts and select transform > rotate. Then define origin, axis and angle to get your model pointed in the right direction. You will have to remesh.
fluid23 is offline   Reply With Quote

Old   September 2, 2015, 12:11
Default
  #8
New Member
 
Xiaosong Zhang
Join Date: Oct 2014
Posts: 14
Rep Power: 11
jsb12136 is on a distinguished road
There is another way to do this. Make sure you have 2 regions. One region is a disk region which has the airfoil in it and the other one is the stationary fluid domain. Simply rotate the first domain to fit your AOA. Hope that will help.
jsb12136 is offline   Reply With Quote

Old   October 2, 2015, 04:31
Default
  #9
New Member
 
fangwei
Join Date: Sep 2015
Posts: 4
Rep Power: 10
yshen303 is on a distinguished road
in the inlet boundary condition if i change the angle of attack by change the directional vector.like below
for example
X-direction 1
Y-direction 0
which is 0 angle of attack. right?
X-direction 0.97814760073
Y-direction 0.20791169081775931
which is 12 degree angle of attack. right?

if i change the AOA, do i have to change the axis for the life and drag?
yshen303 is offline   Reply With Quote

Old   October 2, 2015, 04:32
Default
  #10
New Member
 
fangwei
Join Date: Sep 2015
Posts: 4
Rep Power: 10
yshen303 is on a distinguished road
Quote:
Originally Posted by MBdonCFD View Post
1. As LuckyTran implied but did not specify, your drag vector must point in the same direction as freestream flow. Lift is perpendicular to that. So if you are changing your velocity vector then your force vectors must change too. You can also define the vectors along the chord line and normal to the chord line to get normal and axial force, then simply transform those using: L=N*cos(AOA)-A*sin(AOA), and D=N*sin(AOA)+A*cos(AOA).

2. No need to rotate in CAD if you want to move model WRT flow direction. There is a transform and rotate function if you right click the geometry under parts and select transform > rotate. Then define origin, axis and angle to get your model pointed in the right direction. You will have to remesh.


in the inlet boundary condition if i change the angle of attack by change the directional vector.like below
for example
X-direction 1
Y-direction 0
which is 0 angle of attack. right?
X-direction 0.97814760073
Y-direction 0.20791169081775931
which is 12 degree angle of attack. right?

if i change the AOA, do i have to change the axis for the life and drag?
yshen303 is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
[ICEM] generating new mesh when changing Angle of Attack Nick R ANSYS Meshing & Geometry 4 April 17, 2012 18:33
ASME CFD Symposium, Atlanta, July 2001 Chris R. Kleijn Main CFD Forum 0 September 13, 2000 05:48
ASME CFD Symposium, Atlanta, July 2001 Chris R. Kleijn Main CFD Forum 0 August 21, 2000 05:49
Which is better to develop in-house CFD code or to buy a available CFD package. Tareq Al-shaalan Main CFD Forum 10 June 13, 1999 00:27
public CFD Code development Heinz Wilkening Main CFD Forum 38 March 5, 1999 12:44


All times are GMT -4. The time now is 22:08.