Hello everyone, I am facing a problem with the convergence graph.

Before, I ran 300 iterations for my solution and I was unable to reach convergence. This is the graph I have achieved.

After that, I ran 850 iterations and reached convergence. The graph is as shown below.

I observed that there is a big spike at around 400~500 iterations. I am not so sure about convergence as I am still a beginner at ANSYS Fluent. I am not sure if there is a problem with this graph and if my convergence is correct or wrong.

Please help!