grid sensitivity analysis

[Xythras]

hello to everyone, I was wondering about the sensitivity analysis of the grid solution, if you hesitate a formula or a criterion to determian from which cell dimansion makes sense to start fictitious, obviously note the size of the simulation volume.
and second question, in question where temperature profiles and therefore heat exchange are part of the results that you want to analyze, does it make sense to conduct this analysis by imposing the condition of adiabacity on solid walls?
I was suggested by one of my "tutor", but I didn't consider it because I think it made no sense.
Thanks for the answers.

 

[Xythras]

the first question, I realize now can be placed more clearly, taking as a reference to measure the shortest edge of your simulation volume, what is the maximum percentage of its length from which you can start to generate grids, then go to fix them?
in my case being a conduit take the minino diameter of the section?

 

[Vmax]

In general I never give advice to students because I think the best way to learn is to miss a sufficient number of times, but in your case I make this single exception because you are in bad hands.
on the grid size there is no general formula, keep in mind that the grid must be able to solve the flow well.
on the study of sensitivity you are right, you have to do it under non-adiabatic conditions, your tutor said a worldwide cow and it would be better for everyone to take care of anything else.. .

 

[Xythras]

thanks to the answer, I had arisen the doubt that there was some empirical method to determine from what size of the cells to start, but at this point it seems clear that it is dictated by experience.