= Shear and pressure force partition in cylinder lubrication
{title2=$F_w^{s}=2\mu UJ_1,\quad F_c^{s}=-2\mu WJ_1,\quad F_c^{p}=2\mu(W-U)J_1$}
In the translating-cylinder frame, a wall moves at $-U$ and the nearby cylinder surface at $W$. With gap $d+x^2/(2a)$ and equal outer <pressures>, <lubrication theory> gives the displayed forces with $J_1=\pi\sqrt{2a/d}$. Wall and cylinder shear forces alone do not balance because the sloping cylinder's <pressure force> is of the same order. Their complete sum is zero. <Pressure> exerts no moment about the circular cylinder center, while shear supplies the leading singular rotational resistance.
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