Even displacement correction in an orbit-averaged stresslet ($⟨\mathbf{u}⟩-G_{\mathrm{eff}}=O(S{R}^2/(\mu r^4))$)

Opposite points on the orbit have opposite displacement and the same stresslet director up to sign. Their paired fields are $[G(\mathbf{r}-R\mathbf{p},\mathbf{e})+G(\mathbf{r}+R\mathbf{p},\mathbf{e})]/2$, so odd displacement powers cancel. Since a stresslet decays as $r^{-2}$, the first correction to its far-field orbit average of a tangent stresslet is $O(S{R}^2/(\mu r^4))$. The finite-radius mean need not be an exact point stresslet.