I don't know how to define the aerodynamic center when using multi element wing airfoil just like picture below.
Plz answer me, this is my important project idea.
My current calculation is similar with your project, but it is for the time-dependent deformation. You can numerically integrate the equation given from the NASA lecture to calculate the Center of Pressure. Substituting the average pressure, P(x), in the equation by the average resultant force F(x) on the small wing segments, then you can find out the aerodynamic center where the aerodynamic force acting through.
For the details, you can access the link below for that lecture.
https://www.grc.nasa.gov/www/k-12/airplane/cp.html
From the software, you can extract the force at the coordinates on the wing surface, depending on your mesh element. Then, you can determine the "x" term, which is the distance from the local points to the reference line (based on your definition and it can be from the leading edge of the top wing or from the trailing edge of the bottom wing). Besides, you can also compute the small segment distance, shown as the "dx" term, of these points.
Or you can divide the wing by several equal segments. It can be good enough for about 20 segments in each airfoil element. The average force of each segment, F_average(x_i) can be computed, and the constant segment distances, dx_i, are easily estimated by simple calculations. The accuracy depends on the number of your wing segments. If your case is transient simulation. You can take the cycle-average forces. Good luck.
This is what the transient pressure, stream function, and vorticity look like... http://dudleybenton.altervista.org/projects/CFD/airfoils.gif
First of all, Thanks for your nice answers.
Our team eventually determined aerodynamic center by dividing lift coefficeint for each airfoil. We just defined each airfoil's aerodynamic center by 25% length of chord. And then, we found lift coefficient by ANSYS, calculate whole moment coefficient.
If we have enough time, we hope dividing the wing by several segments, but our project just overdue, so this topic would be the next project title.
Thanks again for your help, and sorry for my bad english.
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