 Solution

The incident uniform flow $U{\mathbf{e}}_z$ has spherical components $u_r=U\cos \theta$, $u_{\theta }=-U\sin \theta$. Integrating the Stokes streamfunction formulas, with the additive constant chosen to vanish on the axis, givesIt is regular at the origin. Applying the sphere theorem for a Stokes streamfunction yieldsThe resulting velocity components areTo find the velocity potential, integrate ${\varphi }_r={\tilde{u}}_r$ and verify $r^{-1}{\varphi }_{\theta }={\tilde{u}}_{\theta }$. This givesThe first term is the incident uniform flow, and the second is a potential dipole located inside the excluded sphere. At $r=a$, the radial velocity vanishes, while the far-field velocity tends to $U{\mathbf{e}}_z$. The poles are stagnation points; the surface tangential speed reaches $3U/2$ at the equator. These formulas describe uniform potential flow around a fixed sphere.