# How can i get the normal and shear force on a wall?

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 September 5, 2021, 17:30 How can i get the normal and shear force on a wall? #1 New Member   xiasheng Join Date: Sep 2021 Posts: 1 Rep Power: 0 hello, i am doing a 2D calculation result in the cfx. I try to get the lift force and component of a cylinder. lift force is easy, i use force_y@cylinder because flow direction is jast to X. but i have problem of component, i want get force from normal pressure force and shear viscous force. at first, i use theta=atan2(Y-0.005[m],X-0.81[m]) to get the agree of point on the cylinder,[0.81 0.005]is the center of cylinder. for normal pressure force, i use areaInt(p*sin(theta))@cylinder to get it for shear viscous force, i use areaInt(Wall Shear*cos(theta))@cylinder in theroy, lift force=normal pressure force+shear viscous force, but i got (normal pressure force+shear viscous force) bigger than 3xlift force i have checked fluent and it show me same lift force. so i think some error about normal pressure force and shear viscous force can some on help me? and if it is unscrupulous object, how can i get component of lift force?

 September 5, 2021, 18:51 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 16,872 Rep Power: 132 Have you plotted the the theta function and checked it is correct? Also check the p*sin(theta) and Wall Shear*cos(theta) components are correct? __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.