hi, i am currently writing a 3D panel method program which uses triangular panels. i have written the part that calculates the doublet strengths on each panel and these seem to be correct. however i am having trouble determining the pressure coefficients from the doublet strengths. now, for a four-sided panel method the local velocity tangential to the wing panel is the derivative of the doublet strength with respect to distance. this is done using a finite difference approach, by finding the change in doublet strength across adjacent panels and dividing by distance between panel control points. this is done in the spanwise and chordwise directions and then the cp is calculated as follows: cp=1.0-((qinf+ql)^2+qm^2)/(vt^2) where qinf is the local freestream vel, ql is local chordwise vel, qm is local spanwise vel. and vt is the freestream vel. my problem is, how can i adapt this so that it works for triangular panels that may not be regular in shape, size or orientation?