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Hello,
I've been trying to simulate unsteady panel method following Basu and Hancock. I've used Newton Raphson method to find the value of vorticity GAMMA. Once I find the value of GAMMA, use this to find the values of the length and the orientation of the wake panel. (Repeat this loop until the values converge to desired accuracy). But the quadratic equation of vorticity has a negative determinant - i.e no roots. This is happening after a couple of time steps. I've looked at the code so many times and I am not able to find the error.