Multiple Clustered Layer Solutions for Semilinear Elliptic Problems on S

We consider the following superlinear elliptic equation on Sn  ε∆Snu− u+ f(u) = 0 in D; u > 0 in D and u = 0 on ∂D, where D is a geodesic ball on Sn with geodesic radius θ1, and ∆Sn is the Laplace-Beltrami operator on Sn. We prove that for any θ ∈ ( 2 , π) and for any positive integer N ≥ 1, there exist at least 2N + 1 solutions to the above problem for ε sufficiently small. Moreover, the asymptotic behavior of such solutions is also characterized. We then apply this result to the Brezis-Nirenberg problem and establish the existence of solutions which are not minimizers of the associated energy.