  This paper introduces a simple formulation for topology optimization problems
ensuring manufacturability by machining. The method distinguishes itself from
existing methods by using the advection-diffusion equation with Robin boundary
conditions to perform a filtering of the design variables. The proposed
approach is less computationally expensive than the traditional methods used.
Furthermore, the approach is easy to implement on unstructured meshes and in a
distributed memory setting. Finally, the proposed approach can be performed
with few to no continuation steps in any system parameters. Applications are
demonstrated with topology optimization on unstructured meshes with up to 64
million elements and up to 29 milling tool directions.
