Please describe your 🚀 feature request.
Currently, within the heterogeneous branch we have allowed for the addition of heterogeneities such as image based or blobs, but havent considered a form of heterogeneity that would react to its surroundings.
Here, I think it would be a nice feature to be able to have the oxygenation of the muscle (but could be used for other tissue) follow a diffusive model between other components (eg. blood vessels)

Describe the solution you'd like
The addition of a new class in the heterogeneity generator that will apply a 2D diffusive model to the oxygenations of the prestanding structures.

Describe alternatives you've considered
Models could of course be more extensive (eg. including blood flow in vessels, how much oxygen is used by the muscle...), but with the amount of information currently available within the simulations I think this should be sufficient for the time being.