sv0D unit conversion factor

[aabrown100-git]

Current situation

#464

Release Notes

• Adds option for user to provide a conversion factor for pressure and flowrate running an svMultiPhysics/sv0D coupled simulation

Testing

• Added new test case pipe_RCR_sv0D_different_units, which is identical to pipe_RCR_sv0D but uses mmhg and mL for sv0D parameter file. Note that the reference solution for pipe_RCR_sv0D_different_units is identical (in fact the same file) as pipe_RCR_sv0D.

Code of Conduct & Contributing Guidelines

• I agree to follow the Code of Conduct and Contributing Guidelines.

[Copilot]

Pull Request Overview

This PR adds support for unit conversion between 3D (svMultiPhysics) and 0D (svZeroD) coupled simulations. The implementation allows automatic conversion of pressure and flowrate values between different unit systems (e.g., cgs vs. clinical units).

• Adds optional Pressure_conversion_factor and Flowrate_conversion_factor parameters to svZeroDSolver_interface XML configuration
• Implements bidirectional unit conversions: multiply when sending values to 0D model, divide when receiving from 0D model
• Adds test case pipe_RCR_sv0D_different_units to validate mixed-unit coupling (cgs in 3D, mmHg/mL in 0D)

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
Code/Source/solver/Parameters.h	Declares new conversion factor parameters in svZeroDSolverInterfaceParameters
Code/Source/solver/Parameters.cpp	Initializes conversion factor parameters with default value of 1.0
Code/Source/solver/ComMod.h	Adds conversion factor fields to svZeroDSolverInterfaceType
Code/Source/solver/ComMod.cpp	Implements logic to copy conversion factors from parameters to runtime type
Code/Source/solver/svZeroD_subroutines.cpp	Applies conversion factors when exchanging values between 3D and 0D solvers
tests/test_fluid.py	Adds test function for mixed-units case
tests/cases/fluid/pipe_RCR_sv0D_different_units/solver.xml	Solver configuration with cgs units and conversion factors
tests/cases/fluid/pipe_RCR_sv0D_different_units/svzerod_3Dcoupling.json	0D model configuration with clinical units
tests/cases/fluid/pipe_RCR_sv0D_different_units/README.md	Documentation for the mixed-units test case
tests/cases/fluid/pipe_RCR_sv0D/svzerod_3Dcoupling.json	Adds comment documenting original test uses cgs units

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[Copilot]

The comment indicates conversion is applied when initializing state, but doesn't explain the direction. The README states the conversion factor transforms 3D units to 0D units (e.g., dyn/cm² → mmHg), but init_flow is a 3D value being stored in lpn_state_y (0D state). Consider clarifying whether init_flow should be in 3D or 0D units, and if the conversion direction is correct here.

Suggested change

	// Apply flowrate conversion when initializing state
	// Convert init_flow from 3D units to 0D units when initializing state

[Copilot]

Similar to the flowrate initialization, the comment doesn't clarify the direction of conversion. Consider adding details about whether init_press is expected to be in 3D or 0D units, and confirming the multiplication is the correct operation for this initialization path.

Suggested change

	// Apply pressure conversion when initializing state
	// Apply pressure conversion when initializing state.
	// init_press is expected to be in 3D units (e.g., dyn/cm^2 or mmHg).
	// The solver expects pressure in 0D units.
	// Multiplying by solver_interface.pressure_conversion converts from 3D to 0D units.

[codecov]

Codecov Report

❌ Patch coverage is 78.57143% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 67.35%. Comparing base (4db1403) to head (8241336).

Files with missing lines	Patch %	Lines
Code/Source/solver/svZeroD_subroutines.cpp	62.50%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #465   +/-   ##
=======================================
  Coverage   67.35%   67.35%           
=======================================
  Files         169      169           
  Lines       32620    32626    +6     
  Branches     5718     5720    +2     
=======================================
+ Hits        21970    21976    +6     
  Misses      10513    10513           
  Partials      137      137           

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[ktbolt]

I do not approve of these changes.

[aabrown100-git]

Closing without merging. See issue for discussion.