finding local stress and surface tension

I am studying two phase flow (fluid-fluid) flow in a channel and am interested in finding out the local stress along the interface and especially at the triple contact point. I was initially calculating surface tension by finding P_xx, P_yy nd P_zz using "compute stress/atom" and then doing a spatial averaging using "ave/spatial" and then finally using the equation (P_yy+P_zz)/2 - P_xx. But then I wanted to calculate local stress and going through the mail-list found that finding stress by averaging stress/atom might not give accurate results and must use Hardy's approach (

Would appreciate comments on this.