Skills fluidsim
🌊

fluidsim

Safe ⚙️ External commands

Run CFD simulations with Python-based FluidSim

Also available from: davila7

FluidSim brings high-performance computational fluid dynamics to Python. Run Navier-Stokes simulations, analyze turbulence, and visualize results with simple Python commands. No complex Fortran or C++ setup required.

Supports: Claude Codex Code(CC)
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Test it

Using "fluidsim". Run a 2D turbulence simulation and show me the energy spectrum

Expected outcome:

  • Created 2D Navier-Stokes simulation with 256x256 grid
  • Running for 10 time units with viscosity 1e-3
  • Generated energy spectrum showing -5/3 slope in inertial range
  • Saved vorticity field visualization at t=10.0
  • Simulation completed successfully - energy decay rate: 0.95

Using "fluidsim". Configure a stratified flow simulation for internal gravity waves

Expected outcome:

  • Initialized ns2d.strat solver with Brunt-Väisälä frequency N=2.0
  • Set up 256x256 grid with domain size 2pi x 2pi
  • Created dense layer initial condition with Gaussian profile
  • Running for 20 time units with adaptive CFL time stepping
  • Configured output periods for buoyancy and velocity fields

Security Audit

Safe
v4 • 1/17/2026

All 330 static findings are false positives. The scanner incorrectly flagged markdown documentation code blocks as shell commands. The skill is a legitimate scientific computing framework for computational fluid dynamics with no security risks. All detected patterns are documentation examples showing Python code for simulations.

8
Files scanned
1,802
Lines analyzed
1
findings
4
Total audits

Risk Factors

⚙️ External commands (8)
SKILL.md:27-46 SKILL.md:54-345 references/installation.md:14-64 references/simulation_workflow.md:9-152 references/solvers.md:9-85 references/parameters.md:5-195 references/output_analysis.md:9-271 references/advanced_features.md:13-391
Audited by: claude View Audit History →

Quality Score

45
Architecture
90
Maintainability
87
Content
29
Community
100
Security
91
Spec Compliance

What You Can Build

Study 2D turbulence energy cascades

Simulate forced 2D turbulence to observe inverse energy cascade and forward enstrophy cascade phenomena

Model stratified atmospheric flows

Simulate density-stratified flows to study internal gravity waves and atmospheric dynamics

Analyze geophysical vortex dynamics

Use shallow water equations to model ocean eddies and rotating basin dynamics

Try These Prompts

Basic 2D turbulence 
Create a 2D Navier-Stokes simulation with 256x256 grid, run for 10 time units with noise initialization and save vorticity plots
Stratified flow setup 
Set up a stratified 2D simulation with Brunt-Väisälä frequency N=2.0, configure for 20 time units, and initialize with a dense layer
High-resolution 3D 
Configure a 512x512x512 3D Navier-Stokes simulation with MPI support, set viscosity to 1e-5, and enable spectra output
Taylor-Green validation 
Initialize Taylor-Green vortex in 2D, run simulation, and compare energy decay with analytical solution

Best Practices

  • Use powers of 2 for grid resolution (128, 256, 512) for optimal FFT performance
  • Enable CFL condition with CFL=0.5 for stable adaptive time stepping
  • Save physical fields sparingly to manage disk space, use spatial means for time series
  • Test with lower resolution first before scaling to production runs

Avoid

  • Do not use arbitrary grid sizes - stick to powers of 2 for FFT efficiency
  • Avoid setting fixed time steps without CFL checking for turbulent flows
  • Do not save every time step - use appropriate output periods to manage data volume

Frequently Asked Questions

Why are my simulations unstable?
Ensure CFL condition is enabled or use sufficiently small time step. Check viscosity values are not too low for your resolution.
How do I choose the right solver?
Use ns2d for 2D turbulence, ns3d for 3D flows, strat solvers for density-stratified flows, and sw1l for rotating shallow systems.
What is the maximum resolution I can run?
Depends on available memory. A 512x512x512 simulation needs about 8GB RAM. Use MPI parallelization for higher resolutions.
How do I restart a simulation?
Use params.init_fields.type='from_file' and point to the state file in your simulation directory.
Can I run this on my laptop?
Yes for 2D simulations up to 512x512 resolution. For 3D or high-resolution runs, use a workstation or cluster with more memory.
Why use pseudospectral methods?
Spectral methods provide high accuracy for periodic domains and efficient computation of derivatives via FFT algorithms.

Developer Details

Author

K-Dense-AI

License

CeCILL FREE SOFTWARE LICENSE AGREEMENT

Repository

https://github.com/K-Dense-AI/claude-scientific-skills/tree/main/scientific-skills/fluidsim

Ref

main

File structure

📁 references/

📄 advanced_features.md

📄 installation.md

📄 output_analysis.md

📄 parameters.md

📄 simulation_workflow.md

📄 solvers.md

📄 SKILL.md