General question

Hi Dear All,
I have a question especially to those of my friends that they also work for such types of problems.
My first question is that if we have software like Fluent where we can simulate low Reynolds numbers flows for different bluff bodies such as circular, square and rectangular cylinders. Then why we need to study such problems using numerical methods such as LBM.
My second question is in reality the flow past high rise building and bridges when experimentally treated they used the high Reynolds numbers which is related to actual practical applications. So why we study such types of problems for low Reynolds numbers in two-dimensional environment. And we know that in reality such low Reynolds numbers not play so important role. So we study low Reynolds number flows for square, circular cylinders for what purpose.
Thanks
Yuanchaomei

My first question is that if we have software like
Fluent where we can simulate low Reynolds numbers
flows for different bluff bodies such as circular,
square and rectangular cylinders. Then why we need
to study such problems using numerical methods
such as LBM.

fluent is a tool among others which uses a numerical method among others.

My second question is in reality the flow past
high rise building and bridges when experimentally
treated they used the high Reynolds numbers which
is related to actual practical applications. So
why we study such types of problems for low
Reynolds numbers in two-dimensional environment.

with building and bridges the reynolds number is high, but in other domains like micro-fluidics the reynolds number is low.