pressure_flow_utils

High-level API used to run a full pressure-and-flow simulation from placental mesh files and user parameters. This module ties together the parsing, geometry construction, resistance calculation, matrix assembly and solver steps.

Primary entry point

pressures_and_flows(node_filename, element_filename, boundary_conditions, inlet_radius, strahler_ratio_arteries, *, …)

Run a complete pipeline:

  1. Read node/element files using file_parsing_utils.

  2. Validate and normalise bc_utils boundary conditions.

  3. Build vascular geometry with geometry_utils.

  4. Compute resistances (resistance_utils).

  5. Create sparse matrices (matrix_builder).

  6. Solve the system using solve_utils and export CSV outputs.

Key parameters

  • node_filename / element_filename — input mesh files (.ipnode

    / .ipelem) located in input_directory.

  • boundary_conditions — dict with possible keys inlet_pressure,

    inlet_flow and outlet_pressure. Use FetoFlow.bc_utils.generate_boundary_conditions() for convenience.

  • inlet_radius / strahler_ratio_arteries — geometry parameters

    used to set arterial radii by Strahler ordering.

  • viscosity_model — string selecting rheology handling. Supported

    options include constant and variants used by Pries-style models.

Outputs

The function writes CSV files into output_directory containing node pressures and per-element flows. Optionally it can return the graph with pressures and flows saved as attributes by setting return_graph=True.

Example

bcs = { 'inlet_pressure': 12000, 'outlet_pressure': 0 }
pressures_and_flows('placenta.ipnode', 'placenta.ipelem', bcs, inlet_radius=0.002, strahler_ratio_arteries=0.79)

API reference

Function arguments

pressures_and_flows
node_filenamestr

Name of the .ipnode file in input_directory.

element_filenamestr

Name of the .ipelem file in input_directory.

boundary_conditionsdict

Dictionary that may contain keys inlet_pressure, inlet_flow and outlet_pressure. See FetoFlow.bc_utils.generate_boundary_conditions().

inlet_radiusfloat

Inlet radius (m) for arterial root vessels.

strahler_ratio_arteriesfloat

Strahler scaling factor used for arterial radius assignment.

input_directorystr, optional

Directory containing input files. Default is current directory (“.”).

output_directorystr, optional

Directory to write outputs. Default is ./output_data.

flow_output_filename, pressure_output_filenamestr, optional

Filenames for CSV exports of flow and pressure.

arteries_onlybool, optional

If True do not generate a venous mesh; default False.

viscosity_modelstr, optional

Viscosity handling mode. Supported values include constant, pries_network, pries_vessel and flow_dependent.

vessel_typestr, optional

Placeholder for vessel elasticity model. Currently 'rigid' is assumed.

outlet_vein_radius, strahler_ratio_veinsfloat, optional

Required when arteries_only is False; used to build the venous mesh.

anastomosisdict, optional

Optional dict describing an anastomosis to add. Expected keys are node_from, node_to and optional radius.

mufloat, optional

Default dynamic viscosity used for non-capillary vessels (Pa.s).

capillary_modelstr, optional

Capillary modelling choice (e.g. 'analytical2015').

capillary_parametersdict, optional

Parameters controlling the capillary equivalent model. See the source for defaults and expected keys.

radius_filenamestr, optional

If provided, a field filename (.ipfiel) used to seed radii.

other_field_filenamesdict, optional

Mapping of additional field names to filenames to import.

verbose, time_statistics, return_graphbool, optional

Misc flags controlling verbosity, timing output, and whether the function returns a graph object with pressures/flows attached.

networkx.DiGraph or None

When return_graph=True the graph with pressure and flow attributes is returned. Otherwise the function writes CSV output and returns None.

Examples and usage patterns

Single-file run producing CSV outputs

bcs = { 'inlet_pressure': 12000, 'outlet_pressure': 0 }
pressures_and_flows('placenta.ipnode', 'placenta.ipelem', bcs, inlet_radius=0.002, strahler_ratio_arteries=0.79)

Return the graph for further inspection or plotting

G = pressures_and_flows('placenta.ipnode', 'placenta.ipelem', bcs, inlet_radius=0.002, strahler_ratio_arteries=0.79, return_graph=True)
# Inspect per-edge flows
flows = {d['edge_id']: d['flow'] for u,v,d in G.edges(data=True)}

Cross references

  • Boundary dicts should be created using FetoFlow.bc_utils.generate_boundary_conditions().

  • Geometry is constructed with FetoFlow.geometry_utils.create_geometry() and resistances are calculated by FetoFlow.resistance_utils.calculate_resistance().

    • The function performs multiple validation steps on inputs and will

      raise ValueError for incorrect types or missing required arguments (for example, outlet_vein_radius when building the venous mesh).

    • The default capillary parameters are used if capillary_parameters

      is omitted; these defaults are warned about to the user.

    Minimal run (arteries only):

    bcs = {'inlet_pressure': 12000, 'outlet_pressure': 0}
pressures_and_flows('placenta.ipnode', 'placenta.ipelem', bcs, inlet_radius=0.002, strahler_ratio_arteries=0.79, arteries_only=True)

    Full run with venous mesh and custom capillary parameters:

    cap_params = {'num_series':3, 'num_parallel':6, 'num_generations':3}
bcs = {'inlet_pressure': 12000, 'outlet_pressure': 0}
pressures_and_flows('n.ipnode', 'n.ipelem', bcs, inlet_radius=0.002, strahler_ratio_arteries=0.79, outlet_vein_radius=0.002, strahler_ratio_veins=0.8, capillary_parameters=cap_params)

    FetoFlow.geometry_utils.create_geometry(), FetoFlow.resistance_utils.calculate_resistance(), FetoFlow.solve_utils.solve_system()