Smoothening interior boundaries - 3D microstructures

Hi all,

I am trying to smoothen out irregular zigzag patterns that come from meshing voxel-based microstructure domains. For instance, the input mesh I am attaching is the following:

I want to smoothen the zigzags to form a smooth surface boundary but I can’t seem to manage this with -ar or -nr. Moreover, I want the outer domain boundaries not to change.

Is there a way, we could do this with MMG3D? If so how should I proceed?

I am attaching the mesh file as well. (InputMesh.mesh)InputMesh.mesh (1.6 MB)