Standing Non-Linear Waves

This repository contains simulation code for studying the dynamics of standing non-linear waves using the Basilisk flow solver. The code implements both analytical Stokes wave solutions and experimental best-fit initial conditions to investigate wave dynamics with adaptive mesh refinement.

Overview

The project focuses on simulating standing waves using a two-phase flow solver with surface tension. It explores:

• Non-linear wave dynamics using Stokes wave theory
• Adaptive mesh refinement for accurate interface tracking
• Comparison between analytical and experimental initial conditions

Installation and Setup

To ensure you have the necessary tools and a fresh Basilisk installation, use the provided script:

./reset_install_requirements.sh

Function

This script checks for Basilisk installation and compiles it if not present.

OS Compatibility

Designed for macOS and Linux systems.

Dependencies

• Basilisk C (automatically installed)
• C compiler (gcc/clang)
• Make build system

Environment Setup

After running the script, a .project_config file is created, setting BASILISK and PATH automatically.

For a fresh installation:

./reset_install_requirements.sh --hard

Running the Code

Using Makefile (Recommended)

1. Navigate to the test cases directory:

cd testCases

2. Compile and run:

make StokesStandingWaves

Direct Compilation

qcc -O2 -Wall -disable-dimensions StokesStandingWaves.c -o StokesStandingWaves -lm

Execution

The program accepts the following parameters:

./StokesStandingWaves maxLevel Ga Bo A0 ORDER tmax

where:

• maxLevel: Maximum refinement level for adaptive mesh (default: 7)
• Ga: Gallileo number (ratio of gravitational to viscous forces)
• Bo: Bond number (ratio of gravitational to surface tension forces)
• A0: Amplitude of the standing wave
• ORDER: Order of the initial condition (0-8, or -1 for best fit)
• tmax: Maximum simulation time

Features

• Two-phase flow simulation with surface tension
• Adaptive mesh refinement for interface tracking
• Support for both analytical and experimental initial conditions
• Automatic error control and mesh adaptation
• Comprehensive logging and data output

Technical Details

Key Components

• Volume of Fluid (VoF) method for interface tracking
• Height function method for curvature calculation
• Adaptive mesh refinement with error control
• Stokes wave analytical solutions

Physical Parameters

• Density ratio (rho1/rho2): 1000 (water-air like)
• Viscosity ratio (mu2/mu1): 0.01 (water-air like)
• Surface tension coefficient: 1.0/Bo
• Gravity: -1.0 (dimensionless)

Simulation Parameters

• Domain size: 2.0 × 2.0
• Error tolerances:
  • VOF: 1e-3 (interface tracking)
  • Curvature: 1e-6 (height function method)
  • Velocity: 1e-3 (adjust based on Oh number)
• Grid resolution: 128 points per unit length (in post-processing)

Post-Processing Protocol

The simulation output can be processed using a suite of tools in the postProcessScripts/ directory. These tools generate visualizations and extract quantitative data from the simulation results.

Quick Start

1. Navigate to your test case directory:

cd testCases/

2. Run the post-processing script:
   -> The folderToProcess is the name of the folder containing the simulation results (this folder will contain the intermediate folder with all the simulation snapshots).

./postProcessData.sh <folderToProcess>

Components and Tools

1. Post-Processing Script (postProcessData.sh)

• Main script that orchestrates the post-processing workflow
• Copies required executables and scripts to the working directory
• Executes visualization and data extraction routines
• Cleans up temporary files after processing

2. Visualization (video.py)

• Python script for generating visualizations and videos
• Features:
  • Custom color maps for better visualization
  • LaTeX-rendered labels and annotations
  • Automated video generation of wave evolution
• Dependencies:
  • NumPy
  • Matplotlib
  • Subprocess
  • Multiprocessing for parallel processing

3. Data Extraction Tools

• getData: Extracts field data (velocity, pressure, etc.)

  • Usage: ./getData filename zmin rmin zmax rmax nr
  • Outputs: Field values on specified grid points

• getFacets: Extracts interface geometry

  • Usage: ./getFacets filename
  • Outputs: Interface segments as coordinate pairs

Output Files

The post-processing generates several types of output:

1. Video files showing wave evolution
2. Data files containing:
   • Grid points (X, Y)
   • velocity magnitude field vel (saved as vel_rot)
   • vorticity field omega (saved as omega_rot)
   • the vof field f (saved as f_rot).
   • Field values (ux, uy) -- saved as (ux_rot, uy_rot)

Customization

The visualization parameters can be customized in video.py:

• Grid resolution
• Color schemes
• Plot dimensions
• Output format and quality

Troubleshooting

Common issues and solutions:

1. Missing executables: Ensure getData and getFacets are compiled
2. Python dependencies: Install required packages using pip
3. Permission issues: Make sure all scripts are executable (chmod +x)

Project Team

• Vatsal Sanjay (University of Twente)
  • Email: [email protected]

Contributing

If you encounter any issues or have suggestions for improvements, please feel free to open an issue on GitHub. We welcome bug reports, feature requests, and general feedback to help improve the project.

License

This project is licensed under the GNU General Public License v3.0 - see the LICENSE file for details.

Citation

If you use this code in your research, please cite:

@software{vatsal_sanjay_2024_14551990,
  author       = {Vatsal Sanjay},
  title        = {comphy-lab/standing-non-linear-waves: Standing Non-Linear Waves – First Official Release -- v1.0},
  year         = {2024},
  publisher    = {Zenodo},
  version      = {v1.0},
  doi          = {10.5281/zenodo.14551990},
  url          = {https://doi.org/10.5281/zenodo.14551990}
}