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October 12, 2015, 23:38 |
Getting a Negative Drag_Coefficient
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#1 |
New Member
fangwei
Join Date: Sep 2015
Posts: 4
Rep Power: 10 |
Hello Everyone
I am running a 2D simulation over a Airfoil via Fluent. I am getting a good Lift Coefficient, but a negative Drag coefficient. Is there anyone experiencing the same issues while running the CFD? Besides, for the initialization method. Is there difference for Hybird and Standard initialization. which one is better? |
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October 12, 2015, 23:59 |
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#2 |
Member
Bharat
Join Date: Jul 2011
Location: Delhi, India
Posts: 49
Rep Power: 15 |
please check
1) is your mesh fine enogh. 2) is your solution converged. 3) values for force vectors, are they defined correctly for specified AoA.
__________________
chapter 3: -crossing the threshold- |
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October 13, 2015, 00:54 |
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#3 | |
New Member
fangwei
Join Date: Sep 2015
Posts: 4
Rep Power: 10 |
Quote:
for the (3), what is values for force vector?, for the angle of attack, in the farfield setting, the direction of incoming air is defined based on x, y unit vector component. for zero AOA, x:1 y:0 right? |
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October 13, 2015, 01:15 |
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#4 |
Member
Bharat
Join Date: Jul 2011
Location: Delhi, India
Posts: 49
Rep Power: 15 |
yes,
for(drag monitor) specific AoA X=cos(AoA) Y=sin(AoA)
__________________
chapter 3: -crossing the threshold- |
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October 13, 2015, 08:00 |
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#5 |
Member
Devesh Baghel
Join Date: Mar 2009
Posts: 84
Rep Power: 17 |
Hi,
Is direction vector correctly defined while calculation of drag ? sometimes happened, while defining opposite direction of vector which reflects negative value. |
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