Wall Flux integrals - Shear Stress Units??

  • Last Post 16 October 2018
wydlerrc posted this 11 October 2018

Fellow Analysts,

I am trying to calculate the shear stress over a wall in a 2D asymmetric model. I run the sim to good convergence and request the output in surface integrals tab -> wall fluxes -> shear stress.

My issue is that the value reported is in "(Pascal)(m^2)" which leads me to believe Fluent is outputting a force, not a stress. If that was the case I would expect that if I request the axial force along that same wall (x-direction force) I would get the same number (in Newtons); however, this isn't the case. The numbers do not agree to any reasonable percent error.

Am I looking at this wrong? Why is Fluent reporting shear stress in (Pascal)(m^2)?


Thank you,




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abenhadj posted this 11 October 2018

You are using a surface integral that means the shear stress will be multiplied with area of the surface/facets. So the unity will be Pa*m^2. To get the forces use fore reporting and prescribe the direction along which thy will be calculated. Or you check the components of wall shear force acting on your surface. In Fluent you have two or three components of shear force available for postprocessing.

Best regards, Amine

klu posted this 12 October 2018

Hi Ryan,

Can you please attach a screenshot of the geometry and which wall are you trying to postprecessing?

abenhadj posted this 16 October 2018

Can you please tell us if your question has been answered?

Best regards, Amine