Well, yes, you shared a code. An internet search makes it clear that it is likely not fully yours.

You just dumped the code here, without any info on: what is the problem, what you have tried, checked, verified, tested etc.

Are we supposed to do that for you?

What makes it even more frustrating is that this is for a thesis. A piece of work that should be original, reflect your own work and something you should be proud of. Instead, it is a testament to the failure of your teachers to teach you how to ask even the most basic questions. They obviously failed you. I repeat my previous statement. You have no business writing cfd codes. You need to start by learning how to pose questions, how to provide relevant information and how to stop expecting someone else will solve your problems.