Example - Model from Byrne et al. 2020, two umbilical arteries

The previous example predicted steady state blood flow in a branching vascular network with one inlet. Mathematically this is simple, but physiologically the fetoplacental circulation has two inlets (the two umbilical arteries). This example solves the same model as example 1, but allows for two umbilical arteries with an anastomosis between them.

This example is found in the directory placenta-simulations/fetoplacental/two_umb_arteries

The example requires that you have the reprosim libraries installed on your machine. You can find installation instructions here and the libraries themselves here.

If you work in virtual environments, activate a virtual environment in which reprosim is installed and execute the following:

python bloodflow_two_umb_arteries.py

The major differences between this example and the previous one are in the definition of the umbilical arteries and the anastomosis between them. Here you have an option to read in a geometry with or without an anastomosis. You will see in the sample_geometry directory that there are two .ipelem files, one includes an anastomosis and one does not. You can chose between these two geometries using the logical ‘anastomosis’, if this logical is true you need to tell the code 1) which element your anastomosis is, and 2) its radius. In the code, this looks like this:

Anastomosis = False
print('Anastomosis: ' + str(Anastomosis))
anast_elem = 3
anast_radius = 1.0

You will see further down the code, that this logical tells the code to read in the appropriate .ipelem file, and that an optional argument to the define_1d_element_placenta function in reprosim then tells that codebase whether to include an anastomosis or not.

if(Anastomosis):
    define_1d_element_placenta('sample_geometry/FullTree.ipelem',anast_elem)
    export_directory = 'output_anast'
else:
    define_1d_element_placenta('sample_geometry/FullTreeNoAnast.ipelem')
    export_directory = 'output'

The only other major difference now is that you have two inlets, if you copied this geometry as veins you’d then have two outlets. This is non-physiological, but you can chose to merge the two copied outlets in to a single, more physiological umbilical vein. You just have to then let the code know which vessels are to be replaced on the venous side:

umbilical_elem_option = 'single_umbilical_vein'
if(Anastomosis):
    umbilical_elements = [1,2,3,4,5]
else:
    umbilical_elements = [1,2,3,4]

The alternate umbilical_elem_option, which invokes a direct copy is as follows (as per the previous example):

umbilical_elem_option = 'same_as_arterial'