structured quad mesh with transition zone - Computational Science

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

Predictive assembling model reveals the self-adaptive elastic properties of lamellipodial actin networks for cell migration

Demonstration of mesh features: a a structured quad mesh and an

Computer Graphics Group

Linear transition element with two 'hanging' nodes-illustration of

Materials, Free Full-Text

Applied Sciences, Free Full-Text

Demonstration of mesh features: a a structured quad mesh and an

PDF] Quasi-structured quadrilateral meshing in Gmsh - a robust pipeline for complex CAD models

Exploring and machine learning structural instabilities in 2D materials

JMSE, Free Full-Text

Quad‐Mesh Generation and Processing: A Survey - Bommes - 2013 - Computer Graphics Forum - Wiley Online Library

Demonstration of mesh features: a a structured quad mesh and an

JMSE, Free Full-Text