title: Savefig with differents names inside a for loop. Python
body: <p>Im calculating the flow in a lid-driven cavity, and Im plotting the result with a quiver. I want to save the plot in every time step, but obviously, as the name is the same, it´s only keep the last one, how can I do it?</p>
  
  <pre><code>for n in range(nt):
  
     #Here I do all the calculation to obtain the new u and v
  
     uC=0.5*(u[:,1:] + u[:,:-1])
     vC=0.5*(v[1:,:] + v[:-1,:])
  
     plt.cla()
     plt.quiver(x, y, uC, vC);
     plt.draw()
     plt.savefig( "Instant1.png")
  </code></pre>
  
  <p>So, imagine nt = 10, I want to get ten differents png files. Any ideas?
  I aprecciate all your help</p>