3D Unsaturated Porous Media Velocity Fields with PSD and FTLE Analysis

Dataset Description This dataset contains the periodic pore-scale velocity fields directly from OpenFOAM simulations. The velocity fields correspond to a fixed porous geometry under varying saturation levels and are used for Lagrangian and Eulerian flow analysis. Contents Velocity fields (VTK format) VelS35.vtk VelS65.vtk VelS85.vtk VelS100.vtkThese files contain three-dimensional periodic velocity blocks for saturation levels S=0.35,0.65,0.85,1.0. They are used for pathline integration and Lagrangian analysis, including computation of Finite-Time Lyapunov Exponents (FTLE), as well as evaluation of deformation metrics. Velocity data (MATLAB format) S0.35_velocity.mat S0.65_velocity.mat S0.85_velocity.mat S1.0_velocity.matThese files contain structured periodic velocity fields and geometry information formatted for MATLAB. They are used for pore size distribution calculations using the provided MATLAB script. Analysis scripts ftle_pipeline.py: Python script for pathline integration and computation of FTLE from the VTK velocity fields. Pore_size_distribution.mlx: MATLAB live script for computing pore size distributions from the MATLAB velocity data. bash.sh: Utility script for automating preprocessing and batch execution of the analysis pipeline. Notes The velocity fields are periodic in all directions and defined within the fluid phase; solid regions are represented as NaN or masked values in the MATLAB files. These datasets are used to compute pathlines, shear rate fields, and cumulative deformation measures (e.g., FTLE), as well as structural metrics such as pore size distributions.Using VTK files in ParaView:The .vtk files can be directly loaded into ParaView for flow visualization. Streamlines can be generated using the Stream Tracer filter by selecting the velocity field as the vector input and defining a seeding region (e.g., point source, line, or custom source). This allows visualization of flow trajectories and qualitative assessment of transport pathways and deformation patterns.Computing shear rate in ParaView:The shear rate field can be computed directly from the velocity gradients in ParaView. This can be done using the Gradient filter to obtain the velocity gradient tensor, followed by computing the second invariant of the strain-rate tensor (e.g., via the Calculator filter). This provides a scalar field corresponding to the local shear rate, enabling visualization and analysis of deformation intensity across the domain.