Which are the seminar topics for chemical engineering related to fluid mechanics ?

Wind farms are a source of alternate energy. The best utilization of the available location to get maximum energy depends on the aerodynamics surrounding a windmill. 

Fluid dynamics of such wind farms can be an interesting area to explore. You can get some idea from the publications here:

https://scholar.google.co.in/scholar?hl=en&as_sdt=0%2C5&q=Wind+farm+fluid+dynamics+studies&btnG=