OASIS — Offshore Advanced SImulation Software¶

OASIS is a time-domain numerical simulation tool for offshore floating structures, developed in C++ by IHCantabria. It couples potential-flow hydrodynamics with structural and mooring dynamics to predict the motion response of floating platforms under waves, wind and current.

Features¶

Feature	Description
Potential-flow hydrodynamics	First-order radiation/diffraction forces from a pre-computed hydrodynamic database
Second-order wave loads	Fast QTF-based evaluation of slow-drift and sum-frequency excitation forces
Non-linear hydrostatics	Exact Froude–Krylov and restoring forces on the instantaneous wetted surface
Dynamic mooring lines	High-order spectral element formulation with seabed contact and irregular bathymetries
Quasi-static mooring lines	Catenary-based solver for fast preliminary assessments
Wind turbine coupling	Interface to OpenFAST for aero-servo-elastic simulation of floating offshore wind turbines
Morison drag model	Current drag and viscous damping via Morison coefficients
Connectors & fenders	Versatile spring/damper model for multi-body contact and boundary coupling points
Oscillating Water Column	Simplified wave energy converter model with pneumatic chamber dynamics
OpenMP parallelisation	Multi-threaded execution on shared-memory machines

Quick Start¶

1. Install & Build¶

Windows (vcpkg)Linux

vcpkg install armadillo hdf5[cpp] openblas superlu metis:x64-windows
compile.bat

cmake -B build -S . -DCMAKE_BUILD_TYPE=Release
cmake --build build -j$(nproc)

See Installation — Windows or Installation — Linux for full instructions.

2. Run an Example¶

cd examples/body/free_decay/input
../../../../bin/oasis .

See Running Simulations and Examples for details.

Documentation Sections¶

:material-download: Installation

Step-by-step build instructions for Windows (vcpkg) and Linux/HPC clusters.
:material-book-open-variant: User Manual

Input file formats, running simulations, output files, and feature-specific guides for waves, mooring lines, springs, winches, OWCs, wind turbines, and ODE solvers.
:material-code-braces: Developer Manual

Source code architecture, build system details, and contribution guidelines.
:material-math-integral: Theory Manual

Mathematical formulations — hydrostatics, hydrodynamics, mooring line FEM, time integration.
:material-api: API Reference

Auto-generated C++ class and function documentation (Doxygen).

Project Structure¶

oasis/
├── CMakeLists.txt                  Main build system
├── CMakeUserConfig.cmake.template  Template for local build paths
├── compile.bat / compile.sh        Quick build scripts (Windows / Linux)
├── src/                            C++ source code
├── examples/                       Ready-to-run example cases
├── resources/                      Python plotting utilities
├── cmake/                          CMake helper modules
├── docs/                           MkDocs documentation source
│   └── theory-manual/              Theory manual (LaTeX source + assets)
└── resources/                      Python plotting utilities

Project	Description
SeaMotions	BEM solver by IHCantabria that generates the hydrodynamic databases (`.hydb.h5`) consumed by OASIS — first-order radiation/diffraction, QTFs, multi-body and OWC support.
OpenFAST	Aero-servo-elastic wind turbine simulator; OASIS couples to it for floating offshore wind simulations.
FASTurbine wrapper	Thin DLL interface around OpenFAST used by OASIS on Windows.

License¶

Developed by IHCantabria. See license terms for details.