What does turbulent eddy viscosity, Turbulence y+ and turbulence_y stand for ?

Juan Felipe Garzón Romero

Hello everyone. 
I'm doing a simulation of the validation manual of Acusolve,
How can I extract Reynolds stress from post-processing? 

Turbulent Flow Through a Pipe

https://2021.help.altair.com/2021/hwsolvers/acusolve/topics/acusolve/turbulent_flow_through_a_pipe.htm

I have already reached some results. However, I want to extract from the post-processing the Reynold stress to do the following graph. 

The following figure shows the fractional contributions to the total stress from the viscous and Reynolds stresses in the near wall region of channel flow.

that 

I don't know if: 

is Reynold's stress or the following two. 

I don't know what result stands for the Reynold stress from those types of results.

 

The link down below stands for some of the supported results I have reached.

data. https://2021.help.altair.com/2021/hwdesktop/hv/topics/pre_processing/interfacing/hv_cfd_acusolve_reader_r.htm

 

Bill Calver_22424

Hello Juan Felipe,

In the Spalart-Allmaras (SA) turbulence model a single transport equation is solved for the transport of eddy viscosity, nt.  You may be more familiar with two-equation turbulence models, for example k-e, in which two transport equations are solved to satisfy turbulence closure.  One transport equation is solved for turbulent kinetic energy, k, and the other for the dissipation of turbulence, e.  Turbulence_y, on the other hand is a dimensional value of the distance to the nearest wall, used in various turbulence models.  Turbulence_y_plus is the non-dimensional wall distance, as shown in the image you posted. 

Reynolds stresses are not directly available as output from AcuSolve.  However, with certain assumptions you may be able to compute them from available data.  If you would like to look into this further please reach out to your local Account Manager or Application Engineer.

Thank you,

Bill

Juan Felipe Garzón Romero

Thanks a lot