Seastead Simulation Software Comparison

Evaluating open-source options for simulating tensegrity seastead designs in waves

Project Overview

You're designing a seastead with a 40×16 ft living platform supported by four 24-ft angled columns/legs at 45°, with half submerged. The design includes cable tension systems and low-speed thrusters. You need to simulate this structure in waves to evaluate stability, cable tensions, and failure points at various wave heights.

Key requirements: Accurate hydrodynamics for non-linear conditions (legs partially to mostly submerged), visualization capability, open-source, Linux-compatible, and ability to handle tensegrity-like cable structures.

Software Comparison Table

Software	Method	Accuracy	Learning Curve	Visualization	Time to First Sim	Best For
Chrono::FSI-SPH	SPH + FEM + Multibody	High	Medium-High	Good	2-3 weeks	Complex fluid-structure interaction
DualSPHysics	SPH (GPU-accelerated)	High	Medium	Excellent	1-2 weeks	Wave interactions with structures
OpenFOAM + MoorDyn	CFD + Mooring dynamics	Very High	Very High	Medium	4-6 weeks	Most accurate engineering analysis
Capytaine + MoorDyn	BEM + Mooring dynamics	Medium (linear)	Medium	Basic	1 week	Fast frequency-domain analysis
Blender + MantaFlow	SPH/Grid-based fluid	Low-Medium	Medium	Excellent	1-2 weeks	Visualization & concept validation
WEC-Sim (Octave)	BEM + Multibody (Matlab clone)	Medium	Medium	Medium	2-3 weeks	Wave energy converter simulations

Detailed Analysis of Options

1. Chrono::FSI-SPH (Your Current Path)

Advantages: Directly addresses your concern about BEM limitations. Uses Smoothed Particle Hydrodynamics (SPH) which handles large motions and non-linear wave interactions well. Already have some experience with Chrono. Good for cable/mooring systems through Chrono's multibody capabilities.

Challenges: SPH is computationally intensive but your A6000 GPU will help. Learning curve for setting up SPH simulations. Documentation can be sparse.

Time estimate: 2-3 weeks with Claude Code assistance to get a working simulation with cables and waves.

Visualization: Built-in visualization tools in Chrono are decent. Can export to ParaView for professional visualization.

Example video: Search for "Chrono FSI SPH waves" on YouTube

2. DualSPHysics

Advantages: Specifically designed for free-surface hydrodynamics with GPU acceleration. Excellent for wave-structure interaction. Your NVIDIA A6000 is perfect for this. Good documentation and examples for offshore structures.

Challenges: Primarily focused on fluid dynamics - would need coupling with another tool for detailed cable dynamics. Mooring lines can be simulated but may need custom implementation.

Time estimate: 1-2 weeks to get fluid-structure interaction working. Additional time for cable dynamics integration.

Visualization: Excellent built-in visualization and ParaView compatibility.

Example video: DualSPHysics - Wave interaction with floating structure

3. OpenFOAM + MoorDyn

Advantages: Industry-standard CFD with excellent accuracy. MoorDyn is specifically for mooring dynamics. Can handle non-linear waves and complex geometries. Most engineering-accurate solution.

Challenges: Very steep learning curve. Complex setup. Long simulation times even with your powerful hardware. Would need to learn OpenFOAM syntax and case setup.

Time estimate: 4-6 weeks to become productive. However, once mastered, this gives the most reliable engineering results.

Visualization: ParaView integration is excellent but requires learning ParaView as well.

Example video: OpenFOAM waves2Foam tutorial

4. Capytaine + MoorDyn (Python-based)

Advantages: Python-based so Claude Code can help significantly. Capytaine for hydrodynamic coefficients, MoorDyn for cable dynamics. Good for frequency-domain analysis.

Challenges: As you noted, BEM assumes small motions so may not capture extreme wave conditions accurately. Linear assumptions might limit accuracy for your design.

Time estimate: 1 week to get basic simulation running due to Python accessibility.

Visualization: Basic matplotlib plots. Would need separate tool for 3D visualization.

5. Blender + MantaFlow/Physical Starlight

Advantages: World-class visualization. MantaFlow provides decent fluid simulation. Physical Starlight add-on adds more accurate physics.

Challenges: Not engineering-grade accuracy. Difficult to extract precise tension values. More for visualization than engineering analysis.

Time estimate: 1-2 weeks if familiar with Blender.

Note: While Blender can create compelling visualizations, it shouldn't be relied upon for engineering decisions about cable failure points.

6. WEC-Sim with GNU Octave

Advantages: Specifically designed for floating structures in waves. Mooring line capabilities. Can run with GNU Octave (free Matlab alternative).

Challenges: May still use BEM for hydrodynamics. Requires learning Matlab/Octave syntax. Some features might require actual Matlab.

Time estimate: 2-3 weeks if using Octave.

RECOMMENDED APPROACH

Based on your requirements (accuracy for non-linear conditions, visualization, cable dynamics, and powerful hardware), I recommend a two-tiered approach:

Primary Engineering Tool: DualSPHysics for accurate wave-structure interaction simulations. Your NVIDIA A6000 GPU will make SPH simulations relatively fast. Start with wave interaction with fixed/moving cylinders to validate hydrodynamics.
Cable Dynamics: Implement a custom Python script using MoorDyn or develop a simplified cable model in Chrono to work alongside DualSPHysics. Alternatively, use Chrono::FSI-SPH which already integrates multibody and cable systems.
Visualization: Use ParaView (which works with both DualSPHysics and OpenFOAM outputs) for professional engineering visualization. For presentation videos, render in Blender using simulation data.

Estimated timeline to first complete simulation: 2-3 weeks with Claude Code assistance.

Implementation Roadmap

Week 1: Foundation

Install DualSPHysics and run example cases (dam break, floating object)
Create simple cylinder geometry for your leg/float design
Set up regular wave tank simulation
Verify GPU acceleration is working

Week 2: Structure Integration

Create full seastead geometry (platform + 4 angled legs)
Implement constrained motion (pivot points at platform connection)
Add basic cable constraint model (simplified spring-damper initially)
Run simulations in small waves, validate behavior

Week 3: Dynamics & Analysis

Implement proper MoorDyn integration or Chrono cable dynamics
Simulate increasing wave heights
Extract cable tension data, identify slack conditions
Create visualization animations in ParaView

Week 4+: Refinement

Add thrusters as external forces
Test different leg angles and submersion levels
Create parametric study scripts to automatically test variations
Develop failure analysis (cable breakage simulations)

Additional Considerations

Hardware Advantage: Your system (NVIDIA A6000, 64-core Threadripper, 750GB RAM) is exceptionally well-suited for SPH simulations in DualSPHysics and high-fidelity OpenFOAM simulations. You can run larger, more detailed simulations than most researchers.

Model Reusability: Once you establish a workflow for one seastead design, creating simulations for different configurations will be much faster (days instead of weeks). Most changes will involve:

Updating geometry dimensions in your model generator script
Adjusting cable attachment points and lengths
Modifying mass properties in the simulation configuration
Re-running parameter studies

Accuracy Validation: Consider validating your simulations against:

Simple analytical calculations for buoyancy and stability
Physical scale model tests (even simple ones)
Comparing multiple simulation methods (e.g., DualSPHysics vs. OpenFOAM for a simplified case)