Piston Driver Mass-Spring Model

Overview

This repository contains a mass-spring (MS) model of pressure oscillations in a confined liquid column subjected to impulsive gas loading. The model represents the liquid column as coupled mass-spring elements and is compared with selected CFD results produced with the ECOGEN solver.

Capabilities

• Simulate water and lithium column responses over selected driving pressures and piston mass ratios.
• Compare mass-spring frequencies with an analytical frequency model.
• Compute control-volume energy contributions and transfer fractions.
• Compare predicted upper and lower gas pressures with the included ECOGEN CFD traces.
• Regenerate the research figures from the model and validation data.

Requirements and installation

Run the commands below from the repository root. This repository is not packaged for installation; use a Python environment with the direct dependencies installed:

python -m pip install numpy scipy matplotlib

Quick start

Generate the analytical-frequency comparison figure:

python -m scripts.figures.figure6_frequency_model_validation

The result is written to figures/figure6_frequency_model_validation.pdf.

Reproducing the figures

To generate the complete figure set, run:

python -m scripts.make_figures

Generated files are written to figures/. The complete workflow runs the parameter-study and energy-analysis calculations and is computationally substantial. It also includes the CFD-validation comparison, which requires the datasets in data/cfd/.

Individual figures can be generated as modules, for example:

python -m scripts.figures.figure_cfd_vs_ms_validation

Model inputs and outputs

The principal geometry, material properties, initial pressures, driving pressures, and piston mass ratios are defined in src/parameters.py.

• scripts/run_parametric_study.py runs the predefined mass-spring simulation cases.
• scripts/data_energy.py derives control-volume energy quantities from those cases.
• scripts/figures/ contains the individual research-figure workflows.
• figures/ receives generated figures.

The included validation datasets are inputs to scripts/figures/figure_cfd_vs_ms_validation.py. Details of their contents and use are in data/README.md.

CFD validation data

data/cfd/ contains upper- and lower-gas pressure traces for the water validation case at a 5 MPa driving pressure and mass ratio M = 0.89. They are used to compare the mass-spring results with ECOGEN CFD results. See data/README.md for filenames, columns, units, and workflow usage.

Repository structure

.
├── src/                  # Core model, analysis, and plotting modules
├── scripts/              # Parameter study, energy analysis, and figure workflows
│   └── figures/          # One script per research figure
├── data/
│   └── cfd/              # ECOGEN validation traces
├── figures/              # Generated figure outputs
├── README.md
└── LICENSE

Authors

• Tiphaine Bloch
• Fabian Denner

License

The code in this repository is released under the MIT License.