excess shear stress in Flow3D
 

I have to analyze the shear stress acting on a river bed. In Flow3D v9.4 i have the output "Excess Shear Stress" in several cells near the river bed. But what's the unit of this shear stress? N/m2? And how can i calculate the shear stress directly on the river bed?

The Excess Shear Stress output is given only for cells that contain fractional solid or packed sediment volumes, so the cells you're seeing near the bed must include some of the bed as well. The units of shear stress are Pascal in SI units, psf in U.S. units.