Jexpresso Visualization Tool

Author: Alex Antonorsi Spring 2026

Interactive Julia tool for inspecting simulation output obtained from JExpresso. It supports 3D time series, 2D slices/planes, multi-piece .pvtu timesteps, and exports selected plots/data to PNG or NetCDF.

Requirements

• Julia
• Julia packages:
  • GLMakie
  • ReadVTK
  • Statistics from the Julia standard library

Install the external packages from the Julia REPL if needed:

import Pkg
Pkg.add(["GLMakie", "ReadVTK"])

Running

From the repository directory:

julia tool.jl

The tool first opens a startup window with:

• a 3D data folder selector
• a 2D data folder selector
• No 3D data and No 2D data checkboxes
• a Launch button

Use the checkboxes when only one data type is available. For example, select No 3D data and choose a 2D folder to launch only the 2D tabs. Disabled data types are not shown in the main toolbar.

The path fields can be edited directly. The Browse buttons use the operating system folder picker when available.

Data Layout

3D Data

The 3D data selector can point at either a VTK file or a folder.

Supported file inputs:

• .pvd
• .pvtu
• .vtu

Supported folder inputs:

• a folder containing simulation.pvd
• a folder containing top-level .pvtu or .vtu files

When a folder contains simulation.pvd, the tool uses the timesteps listed in that file. Otherwise, top-level .pvtu/.vtu files are sorted by iter_N in their filenames.

Example 3D layout:

output/
  simulation.pvd
  iter_0.pvtu
  iter_0/
    iter_0_1.vtu
    iter_0_2.vtu
  iter_1.pvtu
  iter_1/
    iter_1_1.vtu
    iter_1_2.vtu

Multi-piece .pvtu files are supported. Each <Piece Source="...vtu"/> entry is loaded and concatenated into a single timestep.

2D Data

The 2D data selector accepts the same basic file types:

• .pvd
• .pvtu
• .vtu
• a folder containing simulation.pvd
• a folder containing top-level .pvtu or .vtu files

The default 2D folder is 2d/ inside the repository when it exists.

For time series data, the tool expects coordinates, point-data fields, and 2D mesh connectivity to remain consistent across timesteps.

Main Views

When 3D data is enabled, the main app provides:

• 3D Volume: volume rendering for selected point-data variables
• Slices: XY, YZ, and XZ scalar slices with time and position controls
• Variable': fluctuation/prime-field slices using the configured mean axes
• Mean Profiles: time-averaged mean profiles on XY/YZ/XZ planes
• u'v'w': velocity-stress profiles for u, v, and w
• Exports: 3D NetCDF and PNG export controls

When 2D data is enabled, the main app provides:

• 2D Data: scalar field visualization on the 2D mesh
• 2D Averages: spatial-prime and time-averaged 2D profiles
• 2D Exports: 2D NetCDF and PNG export controls

The toolbar also includes a dark-mode checkbox.

Exports

The export tabs write outputs to user-selected paths.

Default export locations:

• 3D NetCDF: simulation.nc
• 2D NetCDF: 2d_data.nc
• 3D PNG folder: 3d_png/
• 2D PNG folder: 2d_png/

NetCDF exports write scalar point data on regularized coordinate grids. PNG exports save the current configured plots for the enabled data type.

Programmatic Use

The startup GUI is used by default, but main can still be called directly from Julia:

include("tool.jl")

main(
    data_path = "/path/to/3d/output",
    two_d_data_path = "/path/to/2d/output",
    use_3d_data = true,
    use_2d_data = true,
)

For 2D-only use:

main(
    two_d_data_path = "/path/to/2d/output",
    use_3d_data = false,
    use_2d_data = true,
)

For 3D-only use:

main(
    data_path = "/path/to/3d/output",
    use_3d_data = true,
    use_2d_data = false,
)