  Let $G$ be a semi-simple real Lie group without compact factors and $ \Gamma
< G$ a Zariski dense, discrete subgroup. We study the topological dynamics of
positive diagonal flows on $\Gamma \backslash G$. We extend Hopf coordinates to
Bruhat-Hopf coordinates of $G$, which gives the framework to estimate the
elliptic part of products of large generic loxodromic elements. By rewriting
results of Guivarc'h-Raugi into Bruhat-Hopf coordinates, we partition the
preimage in $\Gamma \backslash G$ of the non-wandering set of mixing regular
Weyl chamber flows, into finitely many dynamically conjugated subsets. We prove
a necessary condition for topological mixing, and when the connected component
of the identity of the centralizer of the Cartan subgroup is abelian, we prove
it is sufficient.
