Can anyone here, tell me the model used and list of the transport equations with the relevant boundary condition in sudden pipe expansion please..

try to read the old fluid mechanics book by Hansen, if my memory is ok, it gives an integral analysis of this situation, Good luck

Hi Ahmed, I couldn't find the book you suggested. Do you have any idea for this kind of problem?

typa "fluid mechanics Hansen" in your google search window and see what you get there or you can try amazon.com Most modern books about fluid mechanics are more focused on computer methods rather than the basic approach of Integral analysis, Panton Incompressible flow gives the integral form of the basic equations but nothing more. The same is true about Wilcox Basic Fluid Mechanics. The approach is straightforward, just apply the integral equations to your finite control volume

Computational Fluid Dynamics by Roache and Computational Fluid Mechanics and Heat Transfer by Anderson

boundary conditions are tough. You have many different types for the entrance, and you have the corner at the expansion that is tricky.