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-   -   How can i get the normal and shear force on a wall? (https://www.cfd-online.com/Forums/cfx/238311-how-can-i-get-normal-shear-force-wall.html)

 xiasheng September 5, 2021 17:30

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

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?

 ghorrocks September 5, 2021 18:51

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?

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