set style data linespoints
set xlabel "Cx"
set ylabel "Cz"
set xrange [0:0.14]
set yrange [-0.4:0.8]
set grid
set xtics 0,0.02,0.18
set ytics -0.2,0.2,1.6
set key 0.018,0.75
plot "5000.txt" using 3:2 title "Re=5000", "8000.txt" using 3:2 title "Re=8000", "12000.txt" using 3:2 title "Re=12000", "18000.txt" using 3:2 title "Re=18000", "22000.txt" using 3:2 title "Re=22000", "26000.txt" using 3:2 title "Re=26000", "30000.txt" using 3:2 title "Re=30000", "35000.txt" using 3:2 title "Re=35000", "40000.txt" using 3:2 title "Re=40000", "45000.txt" using 3:2 title "Re=45000" 
set term png medium size 640,480
set output "polaires.png"
rep
set out
set xlabel "i"
set xrange [-3:5]
set xtics -3,1,5
set key -2,0.75
set output "czi.png"
plot "5000.txt" using 1:2 title "Re=5000", "8000.txt" using 1:2 title "Re=8000", "12000.txt" using 1:2 title "Re=12000", "18000.txt" using 1:2 title "Re=18000", "22000.txt" using 1:2 title "Re=22000", "26000.txt" using 1:2 title "Re=26000", "30000.txt" using 1:2 title "Re=30000", "35000.txt" using 1:2 title "Re=35000", "40000.txt" using 1:2 title "Re=40000", "45000.txt" using 1:2 title "Re=45000" 
set out
quit