function potential_flow x=0:0.1:10; y=0:0.1:10; [X,Y] = meshgrid(x,y); U=1.0; alpha_deg=5; alpha=alpha_deg/180.0*pi; Phi = U*(X.*cos(alpha)+Y.*sin(alpha)); Psi = U*(Y.*cos(alpha)-X.*sin(alpha)); contour(Phi,'LineColor','red'); hold on; contour(Psi,'LineColor','blue'); end