svOneD Namespace Reference

3D-1D coupling subroutines. More...

Classes
struct	OneDModelState

Functions
void	init_svOneD (ComMod &com_mod, const CmMod &cm_mod)
	Initialize the 1D solver and populate the initial cplBC state. Called once from baf_ini() after the BC data structures are set up.
void	calc_svOneD (ComMod &com_mod, const CmMod &cm_mod, char BCFlag)
	Advance the 1D solver by one time step and update the coupled BC value.

Detailed Description

3D-1D coupling subroutines.

These routines interface the 3D finite-element solver svMultiPhysics with the 1D blood-flow solver svOneDSolver via a dynamically loaded shared library, such as libsvOneDSolver_interface.so or libsvOneDSolver_interface.dylib.

Coupling overview

NEU coupling, where the 1D inlet is driven by the 3D outflow:

• 3D to 1D: flow rate Q, passed through params[3] and params[4].
• 1D to 3D: pressure P, returned through cpl_value.
• 3D boundary condition: Neumann pressure traction.

DIR coupling, where the 1D outlet is driven by the 3D pressure:

• 3D to 1D: pressure P, passed through params[3] and params[4].
• 1D to 3D: flow rate Q, returned through cpl_value.
• 3D boundary condition: Dirichlet velocity profile.

Parallelism model

Unlike the 0D solver, which is solved once on the master rank, each 1D model is independent and has its own input file. Multiple 1D models are therefore read, initialized, and solved in parallel.

Initialization in init_svOneD() has two phases:

• Parallel initialization:
  • Collect all svOneD-coupled faces into a list indexed from 0 to N-1.
  • Assign face/model k to MPI rank k % nProcs.
  • Each rank reads and initializes only its owned model(s), with no MPI synchronization, so all ranks work simultaneously.
• Batch metadata exchange:
  • After all ranks finish initializing their owned model(s), share system_size and coupled_dof via MPI_Bcast so that all ranks know the sizes needed for subsequent result broadcasts.

Time stepping in calc_svOneD() also has two phases:

• Parallel solve:
  • Each rank runs the 1D solve for its owned model(s), with no MPI calls, so different models can run concurrently on different ranks.
• Batch result exchange:
  • After all ranks finish solving, results are shared via MPI_Bcast so that all ranks know each result and can update the corresponding coupled boundary condition value.

Parameters passed to run_1d_simulation_step_1d_

• params[0]: number of time points, currently 2.0.
• params[1]: t_old, the time at the start of the step.
• params[2]: t_new, the time at the end of the step.
• params[3]: BC_val_old, the coupled Q or P value at t_old.
• params[4]: BC_val_new, the coupled Q or P value at t_new.

Function Documentation

calc_svOneD()

void svOneD::calc_svOneD	(	ComMod &	com_mod,
		const CmMod &	cm_mod,
		char	BCFlag
	)

Advance the 1D solver by one time step and update the coupled BC value.

Parameters

BCFlag

'D' - derivative / perturbation step (state is NOT committed). 'L' - last Newton iteration (state IS committed, time advances).

init_svOneD()

void svOneD::init_svOneD	(	ComMod &	com_mod,
		const CmMod &	cm_mod
	)

Initialize the 1D solver and populate the initial cplBC state. Called once from baf_ini() after the BC data structures are set up.