Computing Laplace-Dirichlet maps provide an elegant tool for describing the distance between defined boundaries. Specialized software routines exploiting these maps in order to assign ventricular fibers and sheets or to determine the set of elements to receive heterogeneous conductivities are frequently used in the carputils framework. To run the experiments of this example change directories as follows:
The geometry and the electrodes are defined as follows:
The relevant part of the .par file for this example is shown below:
experiment = 2 # perform Laplace solve only bidomain = 1 # ground electrode stimulus.x0 = -50. # par-file units are always microns! stimulus.xd = 100. stimulus.y0 = -50. stimulus.yd = 10100. stimulus.z0 = -50. stimulus.zd = 200. stimulus.stimtype = 3 # extracellular ground # stimulus electrode stimulus.x0 = -50. stimulus.xd = 10100. stimulus.y0 = -50. stimulus.yd = 100. stimulus.z0 = -50. stimulus.zd = 200. stimulus.stimtype = 2 # extracellular voltage stimulus.duration = 1. stimulus.strength = 1. # set isotropic conductivities everywhere num_gregions = 1 gregion.g_il = 1 gregion.g_it = 1 gregion.g_el = 1 gregion.g_et = 1
To run this experiment, do
meshtool<mesh-data-extraction>will help you to reintegrate any computed features back into its 'parent'.
Instead of having to define a different stimulus for each different Dirichlet value, specific nodes can be assigned different values in one file. The relevant parameters to change are below:
stimulus.stimtype = 2 # extracellular voltage stimulus.vtx_file = BCs stimulus.vtx_fcn = 1 stimulus.strength = 1.
stimulus.vtx_fcn is non-zero, the
vtx_file, BCs.vtx in this case, has vertex adjustment format in which the nodal strength is specified along with the node number. The nodal strengths in the file are then multiplied by