fluidsim▌
K-Dense-AI/scientific-agent-skills · updated Jun 4, 2026
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### Fluidsim
- ›name: "fluidsim"
- ›description: "Framework for computational fluid dynamics simulations using Python. Use when running fluid dynamics simulations including Navier-Stokes equations (2D/3D), shallow water equations, stratified flows, o..."
| name | fluidsim |
| description | Framework for computational fluid dynamics simulations using Python. Use when running fluid dynamics simulations including Navier-Stokes equations (2D/3D), shallow water equations, stratified flows, or when analyzing turbulence, vortex dynamics, or geophysical flows. Provides pseudospectral methods with FFT, HPC support, and comprehensive output analysis. |
| license | CeCILL FREE SOFTWARE LICENSE AGREEMENT |
| metadata | version: "1.0" skill-author: K-Dense Inc. |
FluidSim
Overview
FluidSim is an object-oriented Python framework for high-performance computational fluid dynamics (CFD) simulations. It provides solvers for periodic-domain equations using pseudospectral methods with FFT, delivering performance comparable to Fortran/C++ while maintaining Python's ease of use.
Key strengths:
- Multiple solvers: 2D/3D Navier-Stokes, shallow water, stratified flows
- High performance: Pythran/Transonic compilation, MPI parallelization
- Complete workflow: Parameter configuration, simulation execution, output analysis
- Interactive analysis: Python-based post-processing and visualization
Core Capabilities
1. Installation and Setup
Install fluidsim using uv with appropriate feature flags:
# Basic installation
uv pip install fluidsim
# With FFT support (required for most solvers)
uv pip install "fluidsim[fft]"
# With MPI for parallel computing
uv pip install "fluidsim[fft,mpi]"
Set environment variables for output directories (optional):
export FLUIDSIM_PATH=/path/to/simulation/outputs
export FLUIDDYN_PATH_SCRATCH=/path/to/working/directory
No API keys or authentication required.
See references/installation.md for complete installation instructions and environment configuration.
2. Running Simulations
Standard workflow consists of five steps:
Step 1: Import solver
from fluidsim.solvers.ns2d.solver import Simul
Step 2: Create and configure parameters
params = Simul.create_default_params()
params.oper.nx = params.oper.ny = 256
params.oper.Lx = params.oper.Ly = 2 * 3.14159
params.nu_2 = 1e-3
params.time_stepping.t_end = 10.0
params.init_fields.type = "noise"
Step 3: Instantiate simulation
sim = Simul(params)
Step 4: Execute
sim.time_stepping.start()
Step 5: Analyze results
sim.output.phys_fields.plot("vorticity")
sim.output.spatial_means.plot()
See references/simulation_workflow.md for complete examples, restarting simulations, and cluster deployment.
3. Available Solvers
Choose solver based on physical problem:
2D Navier-Stokes (ns2d): 2D turbulence, vortex dynamics
from fluidsim.solvers.ns2d.solver import Simul
3D Navier-Stokes (ns3d): 3D turbulence, realistic flows
from fluidsim.solvers.ns3d.solver import Simul
Stratified flows (ns2d.strat, ns3d.strat): Oceanic/atmospheric flows
from fluidsim.solvers.ns2d.strat.solver import Simul
params.N = 1.0 # Brunt-Väisälä frequency
Shallow water (sw1l): Geophysical flows, rotating systems
from fluidsim.solvers.sw1l.solver import Simul
params.f = 1.0 # Coriolis parameter
See references/solvers.md for complete solver list and selection guidance.
4. Parameter Configuration
Parameters are organized hierarchically and accessed via dot notation:
Domain and resolution:
params.oper.nx = 256 # grid points
params.oper.Lx = 2 * pi # domain size
Physical parameters:
params.nu_2 = 1e-3 # viscosity
params.nu_4 = 0 # hyperviscosity (optional)
Time stepping:
params.time_stepping.t_end = 10.0
params.time_stepping.USE_CFL = True # adaptive time step
params.time_stepping.CFL = 0.5
Initial conditions:
params.init_fields.type = "noise" # or "dipole", "vortex", "from_file", "in_script"
Output settings:
params.output.periods_save.phys_fields = 1.0 # save every 1.0 time units
params.output.periods_save.spectra = 0.5
params.output.periods_save.spatial_means = 0.1
The Parameters object raises AttributeError for typos, preventing silent configuration errors.
See references/parameters.md for comprehensive parameter documentation.
5. Output and Analysis
FluidSim produces multiple output types automatically saved during simulation:
Physical fields: Velocity, vorticity in HDF5 format
sim.output.phys_fields.plot("vorticity")
sim.output.phys_fields.plot("vx")
Spatial means: Time series of volume-averaged quantities
sim.output.spatial_means.plot()
Spectra: Energy and enstrophy spectra
sim.output.spectra.plot1d()
sim.output.spectra.plot2d()
Load previous simulations:
from fluidsim import load_sim_for_plot
sim = load_sim_for_plot("simulation_dir")
sim.output.phys_fields.plot()
Advanced visualization: Open .h5 files in ParaView or VisIt for 3D visualization.
See references/output_analysis.md for detailed analysis workflows, parametric study analysis, and data export.
6. Advanced Features
Custom forcing: Maintain turbulence or drive specific dynamics
params.forcing.enable = True
params.forcing.type = "tcrandom" # time-correlated random forcing
params.forcing.forcing_rate = 1.0
Custom initial conditions: Define fields in script
params.init_fields.type = "in_script"
sim = Simul(params)
X, Y = sim.oper.get_XY_loc()
vx = sim.state.state_phys.get_var("vx")
vx[:] = sin(X) * cos(Y)
sim.time_stepping.start()
MPI parallelization: Run on multiple processors
mpirun -np 8 python simulation_script.py
Parametric studies: Run multiple simulations with different parameters
for nu in [1e-3, 5e-4, 1e-4]:
params = Simul.create_default_params()
params.nu_2 = nu
params.output.sub_directory = f"nu{nu}"
sim = Simul(params)
sim.time_stepping.start()
See references/advanced_features.md for forcing types, custom solvers, cluster submission, and performance optimization.
Common Use Cases
2D Turbulence Study
from fluidsim.solvers.ns2d.solver import Simul
from math import pi
params = Simul.create_default_params()
params.oper.nx = params.oper.ny = 512
params.oper.Lx = params.oper.Ly = 2 * pi
params.nu_2 = 1e-4
params.time_stepping.t_end = 50.0
params.time_stepping.USE_CFL = True
params.init_fields.type = "noise"
params.output.periods_save.phys_fields = 5.0
params.output.periods_save.spectra = 1.0
sim = Simul(params)
sim.time_stepping.start()
# Analyze energy cascade
sim.output.spectra.plot1d(tmin=30.0, tmax=50.0)
Stratified Flow Simulation
from fluidsim.solvers.ns2d.strat.solver import Simul
params = Simul.create_default_params()
params.oper.nx = params.oper.ny = 256
params.N = 2.0 # stratification strength
params.nu_2 = 5e-4
params.time_stepping.t_end = 20.0
# Initialize with dense layer
params.init_fields.type = "in_script"
sim = Simul(params)
X, Y = sim.oper.get_XY_loc()
b = sim.state.state_phys.get_var("b")
b[:] = exp(-((X - 3.14)**2 + (Y - 3.14)**2) / 0.5)
sim.state.statephys_from_statespect()
sim.time_stepping.start()
sim.output.phys_fields.plot("b")
High-Resolution 3D Simulation with MPI
from fluidsim.solvers.ns3d.solver import Simul
params = Simul.create_default_params()
params.oper.nx = params.oper.ny = params.oper.nz = 512
params.nu_2 = 1e-5
params.time_stepping.t_end = 10.0
params.init_fields.type = "noise"
sim = Simul(params)
sim.time_stepping.start()
Run with:
mpirun -np 64 python script.py
Taylor-Green Vortex Validation
from fluidsim.solvers.ns2d.solver import Simul
import numpy as np
from math import pi
params = Simul.create_default_params()
params.oper.nx = params.oper.ny = 128
params.oper.Lx = params.oper.Ly = 2 * pi
params.nu_2 = 1e-3
params.time_stepping.t_end = 10.0
params.init_fields.type = "in_script"
sim = Simul(params)
X, Y = sim.oper.get_XY_loc()
vx = sim.state.state_phys.get_var("vx")
vy = sim.state.state_phys.get_var("vy")
vx[:] = np.sin(X) * np.cos(Y)
vy[:] = -np.cos(X) * np.sin(Y)
sim.state.statephys_from_statespect()
sim.time_stepping.start()
# Validate energy decay
df = sim.output.spatial_means.load()
# Compare with analytical solution
Quick Reference
Import solver: from fluidsim.solvers.ns2d.solver import Simul
Create parameters: params = Simul.create_default_params()
Set resolution: params.oper.nx = params.oper.ny = 256
Set viscosity: params.nu_2 = 1e-3
Set end time: params.time_stepping.t_end = 10.0
Run simulation: sim = Simul(params); sim.time_stepping.start()
Plot results: sim.output.phys_fields.plot("vorticity")
Load simulation: sim = load_sim_for_plot("path/to/sim")
Resources
Documentation: https://fluidsim.readthedocs.io/
Reference files:
references/installation.md: Complete installation instructionsreferences/solvers.md: Available solvers and selection guidereferences/simulation_workflow.md: Detailed workflow examplesreferences/parameters.md: Comprehensive parameter documentationreferences/output_analysis.md: Output types and analysis methodsreferences/advanced_features.md: Forcing, MPI, parametric studies, custom solvers
How to use fluidsim on Cursor
AI-first code editor with Composer
Prerequisites
Before installing skills in Cursor, ensure your development environment meets these requirements:
- ›Cursor installed and configured on your development machine
- ›Node.js version 16.0+ with npm package manager (verify with
node --version) - ›Active project directory or workspace where you want to add fluidsim
Execute installation command
Execute the skills CLI command in your project's root directory to begin installation:
The skills CLI fetches fluidsim from GitHub repository K-Dense-AI/scientific-agent-skills and configures it for Cursor.
Select Cursor when prompted
The CLI will show a list of available agents. Use arrow keys to navigate and space to select Cursor:
Verify installation
Confirm successful installation by checking the skill directory location:
Reload or restart Cursor to activate fluidsim. Access the skill through slash commands (e.g., /fluidsim) or your agent's skill management interface.
Security & Verification Notice
We perform automated surface-level scans (Gen AI Scanner, Socket, Snyk) during installation. These checks detect common vulnerabilities but do not guarantee complete security. Always review skill source code and verify the publisher's reputation before production use.
Skills execute code in your development environment. Always verify the publisher's identity, review recent commits, and test in isolated environments before production deployment.
List & Monetize Your Skill
Submit your Claude Code skill and start earning
Use Cases▌
Task Automation & Efficiency
Automate repetitive workflows and reduce manual effort
Example
Generate reports, summarize documents, draft communications
Save 3-5 hours per week on routine tasks
Knowledge Enhancement
Learn new skills, understand complex topics, get expert guidance
Example
Explain concepts, provide examples, suggest learning resources
Accelerate learning and skill development by 2x
Quality Improvement
Enhance output quality through reviews, suggestions, and refinements
Example
Review drafts, suggest improvements, catch errors
Improve work quality by 30-40% with less effort
Implementation Guide▌
Prerequisites
- ›Claude Desktop or compatible AI client with skill support
- ›Clear understanding of task or problem to solve
- ›Willingness to iterate and refine outputs
Time Estimate
15-45 minutes depending on use case complexity
Installation Steps
- 1.Install skill using provided installation command
- 2.Test with simple use case relevant to your work
- 3.Evaluate output quality and relevance
- 4.Iterate on prompts to improve results
- 5.Integrate into regular workflow if valuable
Common Pitfalls
- ⚠Expecting perfect results without iteration
- ⚠Not providing enough context in prompts
- ⚠Using skill for tasks outside its intended scope
- ⚠Accepting outputs without review and validation
Best Practices▌
✓ Do
- +Start with clear, specific prompts
- +Provide relevant context and constraints
- +Review and refine all outputs before using
- +Iterate to improve output quality
- +Document successful prompt patterns
✗ Don't
- −Don't use without understanding skill limitations
- −Don't skip validation of outputs
- −Don't share sensitive information in prompts
- −Don't expect skill to replace human judgment
💡 Pro Tips
- ★Be specific about desired format and style
- ★Ask for multiple options to choose from
- ★Request explanations to understand reasoning
- ★Combine AI efficiency with human expertise
When to Use This▌
✓ Use When
Use when skill capabilities match your task, clear ROI on time saved, and you can validate outputs. Best for repetitive tasks, learning, and quality improvement.
✗ Avoid When
Avoid when task requires deep expertise you can't validate, involves sensitive decisions, or when learning process is more valuable than speed of completion.
Learning Path▌
- 1Familiarize yourself with skill capabilities and limitations
- 2Start with low-risk, non-critical tasks
- 3Progress to more complex and valuable use cases
- 4Build expertise through regular use and experimentation
Discussion
Product Hunt–style comments (not star reviews)- No comments yet — start the thread.
Ratings
4.6★★★★★43 reviews- ★★★★★Sakura Martin· Dec 24, 2024
Registry listing for fluidsim matched our evaluation — installs cleanly and behaves as described in the markdown.
- ★★★★★Ren Liu· Dec 20, 2024
Useful defaults in fluidsim — fewer surprises than typical one-off scripts, and it plays nicely with `npx skills` flows.
- ★★★★★Sakura Brown· Dec 16, 2024
I recommend fluidsim for anyone iterating fast on agent tooling; clear intent and a small, reviewable surface area.
- ★★★★★Shikha Mishra· Dec 12, 2024
fluidsim fits our agent workflows well — practical, well scoped, and easy to wire into existing repos.
- ★★★★★Olivia Lopez· Dec 4, 2024
fluidsim fits our agent workflows well — practical, well scoped, and easy to wire into existing repos.
- ★★★★★Sakura Taylor· Nov 15, 2024
Useful defaults in fluidsim — fewer surprises than typical one-off scripts, and it plays nicely with `npx skills` flows.
- ★★★★★Sakura Lopez· Nov 11, 2024
Registry listing for fluidsim matched our evaluation — installs cleanly and behaves as described in the markdown.
- ★★★★★Noah Choi· Nov 7, 2024
fluidsim reduced setup friction for our internal harness; good balance of opinion and flexibility.
- ★★★★★Noah Perez· Oct 26, 2024
Registry listing for fluidsim matched our evaluation — installs cleanly and behaves as described in the markdown.
- ★★★★★Li Thomas· Oct 6, 2024
I recommend fluidsim for anyone iterating fast on agent tooling; clear intent and a small, reviewable surface area.
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