Learning Forum

[S.Shrestha-4]

Hi!

Is there a way to calculate fluid viscous stress in the exit of the nozzle to calculate the viscous stress contribution to thrust of the nozzle? 

Thanks!

[Federico]

Hello, 

High Viscous Stress Near Walls: At the walls of the nozzle, the fluid velocity is close to zero (no-slip condition), while the fluid in the center moves much faster. This velocity difference causes viscous stress between the fluid layers, which tends to slow the fluid down.

Low Viscous Stress in the Core: Away from the walls, where the velocity is more uniform, viscous stress is much lower.

do you mean to calculate the overall viscous stress for the nozzle? Or are you specifically interested in any viscous stresses at the exit?

[S.Shrestha-4]

I want to calculate the area-averaged viscous stress in the exit plane of nozzle with slip walls condition. So overall viscous stress, that is a field function and taking the average from the surface integrals option.