LAUSR

In this paper, the large time decay of the magneto-micropolar fluid equations on $$\mathbb {R}^n$$Rn ($$ n=2,3$$n=2,3) is studied. We show, for Leray global solutions, that $$ \Vert ({\varvec{u}},{\varvec{w}},{\varvec{b}})(\cdot ,t) \Vert _{{L^2(\mathbb {R}^n)}} \rightarrow 0 $$‖(u,w,b)(·,t)‖L2(Rn)→0 as $$t \rightarrow \infty $$t→∞ with arbitrary initial data in $$ L^2(\mathbb {R}^n)$$L2(Rn). When the vortex viscosity is present, we obtain a (faster) decay for the micro-rotational field: $$ \Vert {\varvec{w}}(\cdot ,t) \Vert _{{L^2(\mathbb {R}^n)}} = o(t^{-1/2})$$‖w(·,t)‖L2(Rn)=o(t-1/2). Some related results are also included.