please help me for general description of CFD
 

hello everyone
i happend to take a presentation of CFD introduction at my work.
there is a number of people only familiar with concent of CFD.
so i prepared for just applications and beginer stuff
but a senior resercher wants to me to clarify about
is there a limit when we use CFD,
what is a design factor of N-S eq, and how's different when open channel flow and closed channel flow in design factor wise.

i studied CFD but i never teach anyone about this so i really need help.
if anyone of you have answers i'll appriciate.

your question is too broad and ambigue to be answered...sorry...
you can find many proper materials from many other well prepared CFD books on CFD resource part of this CFD-online site
and they would be very helpful for your mission...i think...

The main difficulty in numerical simulations like CFD is to come to stability and convergence.Moreover, we need to experimental data to verify our numerical results; however, we can model or simulate almost all kind of fluid flows numerically, which may be more difficult experimentaly.

I agree with justyou..too general question.. There are many factors that you need to evaluate... to start i would look if the formulation of N.S. applies or in other words if you are still in the continuum. ( so check the Kn number for example)
Then you may want to check if you're using a Newtonian fluid.
then you may need to check if you are compress. or incompress

It is possible to simulate most of situation as long as a valid model and enough computational power are available