Hey,
I am a new PhD scholar, joined in March only. I did my M.tech in Biochemical Engineering and was looking for PhD. However, I was not sure about my research area. I grabbed the very first opportunity I got for PhD which was in Chemical Engineering. But now I am feeling totally exhausted because the coursework requires me to study engineering maths (I am from a biology background) and computational fluid dynamics as well as coding in MATLAB. I am unable to understand any of it as I have no basics about the same. What should I do? Should I quit and look for PhD somewhere else?

Hi Choti,
you must have something good to bring to the table or they wouldn't have picked you for the position?
But then again if you really don't like the topic quitting now would be better than in a year or two. Or even apply for others before quitting to see if something else comes up.

Hi Choti,
The big question is do you like the topic. My background is in microbiology and for my PhD I have done quite a bit of chemical engineering- There was stuff I didn't understand and TBH it took a while to get my head around it. I spent a lot of extra time reading the basics so I could understand what I am doing.
If you like the topic- can you ask for extra help ? are there video tutorials you can look at? Can you ask the PI for the suggestion of good books to read.
If you don't like the topic- I would hand in my notice and start looking elsewhere. Personally, I wouldn't stay while looking for something else, as I feel like you'd only be wasting your time and other time.

I did my undergraduate and masters degree in chemical engineering :)
Chemical engineering maths is difficult but any CFD work can be especially difficult. Computer modelling is not a fun place to start but i don't think it would get any more difficult (unless you go towards reaction modelling). You will probably find a lot of other people are struggling and you would hope academics understand that it is on the more difficult end of the spectrum. As Nead suggested, there is a lot of support, advice and educational videos out there can help.
I personally think having a passion for your subject/project makes doing a PhD significantly easier. If you don't enjoy what you are doing you will have less motivation to carry you through the tough times. Is there a part of your PhD that you enjoy? If so focus on that and just endure the CFD parts. Otherwise, there is no shame dropping out of a PhD and applying somewhere else.