outfile = "iron_entry_results.txt"

-- read projectile's position at its centerpoint
handle = openfile("tempfile","r")
position = read(handle,"*n")
closefile(handle)

-- define contour clockwise around the 10mm-long projectile
-- it needs to be ~2 mesh units outside the iron
length = 30			-- length of projectile (mm)
r = 2.25			-- radius of projectile (mm)
mesh = 0.4			-- mesh size inside iron projectile

top = position + length/2 + mesh*2
bot = position - length/2 - mesh*2

add_contour(0, top)		-- upper left
add_contour(r+mesh*2,top)	-- upper right
add_contour(r+mesh*2,bot)	-- lower right
add_contour(0, bot)		-- lower left
add_contour(0, top)		-- and back to start

-- STRESS TENSOR: compute mechanical force upon contour around projectile
radial_force_real, radial_force_imag, axial_force_real, axial_force_imag = line_integral(3)

-- LORENTZ FORCE: mechanical force on coil
-- Note: We can't use the (simpler) Lorentz force calculation because the
-- coil's force is unbalanced due to a single iron end cap.
-- groupselectblock(2)
-- lorentz_force = blockintegral(12) * (-1)

handle=openfile(outfile,"a")
write(handle, position, "\t", axial_force_real, "\n")
closefile(handle)

exitpost()