structured quad mesh with transition zone - Computational Science Stack Exchange

I wonder which software can be used to generate the mesh like below. Anybody has an idea?

Mesh generation

Structured Mesh - an overview

Micromachines, Free Full-Text

Self-organized intracellular twisters

mesh - NDSolve and FEM support for non conformal meshes of a disk

GIS Dictionary

Computational study of the mechanical influence of lacunae and

SIMULATION PARAMETERS & BOUNDARY CONDITIONS

Micromachines, Free Full-Text

Micromachines, Free Full-Text

A 2nd Order Tunable Bandpass Sigma Delta Converter for Material