hi, i am modelling a plate heat exchanger, and i have done every necessary procedure. how can i get a plot of the nusselt number against reynolds number, and also a plot of friction coeff against reynolds number

If fluent does not have these variables (Re, Pr, Cf) ready for plotting you can create Custom Field Functions for defining your own variables for post processing. You can access the custom field function panel through the define menu. You can also create surfaces to plot your newly defined field function contours on any part of your geometry that you see fit. Hope this helps

Regards