calculate avg nusselt no. for 2d convective heat transfer problem
 

My problem is related to convective heat transfer in 2d lid cavity. left wall is taken as lid. i am trying to calculate nusselt number in following way, correct me if i am doing it in wrong way.
1) Nu = hL/k , h=q/(Th-Tc)
2)i took value of q of lid wall from surface integrals<area weighted avg<wall flux<total surface heat flux.
3)then calculate value of h and then calculate value of Nu by putting value of h and k(of fluid).

Is it correct?

Yes it's correct, but becareful if you are measuring Total average Nu number or local Nu number

Thank you for your response. I am measuring avg nusselt number along a wall. I have calculated surface integral of heat flux through wall, that means average nusselt number.. Is it so?