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西岡佳祐 edited this page Mar 15, 2026 · 3 revisions

VirtualElementMethods

VEM × バイオフィルム力学 — 任意多角形/多面体メッシュによるバイオフィルムの機械的解析

Repository: keisuke58/VirtualElementMethods

What is VEM?

VEM (Virtual Element Method) は FEM の一般化で、任意多角形/多面体要素上で弾性問題を解ける。形状関数を明示構成しない ("virtual") 代わりに射影演算子で剛性行列を近似する。

Confocal → VEM (2-step pipeline)

Step FEM (traditional, 5-step) VEM (2-step)
1 Confocal z-stack Confocal z-stack
2 Voxel segmentation Colony centroids → Voronoi
3 Marching cubes VEM solve ← done!
4 Tetrahedral remeshing
5 Abaqus FEM solve

pipeline

VEM Schematic

schematic


Modules

Base VEM

File Description
vem.py 2D Poisson (Sutton 2017 base)
vem_elasticity.py 2D plane-stress elasticity (patch test 1e-18)
vem_3d.py 3D elasticity on polyhedra (patch test 1e-19)
vem_3d_advanced.py 3D Voronoi + sparse solver + VTK export
vem_apple.py Apple-shaped Voronoi demo

Prototypes

File Idea
vem_spacetime.py Space-Time VEM: anisotropic (x,t) Voronoi, SLS 粘弾性
vem_growth_coupled.py Growth-Coupled VEM: 5-species replicator + VEM + cell division
vem_confocal_pipeline.py Confocal → VEM: 5ch confocal → Voronoi → VEM (2-step)
vem_phase_field.py Phase-field VEM: Aldakheel 2018 style 破壊, DI→G_c
vem_nonlinear.py Neo-Hookean VEM: 大変形超弾性, Newton-Raphson
vem_error_estimator.py A posteriori error: ZZ-type, Dörfler marking
process_heine_fish.py Heine 2025 FISH: real image → VEM

3D Real Biofilm (NEW)

File Purpose
pipeline_3d_real.py 3D TIFF → colony segment → Voronoi → VEM
benchmark_3d_vem_vs_tet.py VEM Voronoi vs FEM tet comparison
phase_field_real_3d.py Phase-field fracture on real SAPA biofilm
vem_phase_field_3d.py 3D Phase-field VEM on polyhedral mesh (NEW)

Key Numbers

Metric Value
E range 10–1000 Pa (literature: 20–14,000 Pa)
E ratio CS/DS up to 28×
Convergence L² 2.14 (Voronoi)
3D Real PA 65 cells, E 42–237 Pa
3D Real SAPA 131 cells, DI 0.18–0.79, E 74–682 Pa
Phase-field 2D 69 elements, d_max=0.85, 57/82 cracked
Phase-field 3D 208 polyhedra, catastrophic at step 14, d_max=0.56 pre-cat
Tests 70 passing

Grand Showcase

grand showcase


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