An inscribed radius estimate for mean curvature flow in Riemannian manifolds

Abstract

We consider a family of embedded, mean convex hypersurfaces in a Riemannian manifold which evolve by the mean curvature flow. We show that, given any number $T>0$ and any $\delta>0$, we can find a constant $C_0$ with the following property: if $t \in [0,T)$ and $p$ is a point on $M_t$ where the curvature is greater than $C_0$, then the inscribed radius is at least $\frac{1}{(1+\delta) \, H}$ at the point $p$. The constant $C_0$ depends only on $\delta$, $T$, and the initial data.