Let $M$ be a manifold with two metrics $g,g'$ of Ricci curvature $r_g,r_{g'}$. I define a coupled Ricci flow:
$$\frac{\partial g}{\partial t}=-2 r_{g'}$$
$$\frac{\partial g'}{\partial t}=-2r_g$$
Have we solutions for the coupled Ricci flow for short time?