Ideas for adding heterogeneous/surface reactions

[jgostick]

I've been thinking about heat transfer and heterogeneous reactions.

Idea 1: Split throats to put a "throat node" in the middle of each one

I wonder if there is any value to splitting each throat and adding a new node in the middle. This node would have a known mass/heat transfer coefficient since the flow rate is properly known in a throat. We could also treat it as the "concentration at the wall", and get the bulk concentration as some average of the two neighboring pore values. This way we could include a driving force between the bulk and surface in the reaction. The down side is obviously that it increases the number of unknowns quite a bit.

Idea 2: Fictitious side nodes attached to each pore

This would allow us to solve the bulk concentration in the pore, as we do now, but also have a mass transfer resistance from the pore center to some dead-end 'fictitious' pore where the reaction actually happens. This would not solve the heat/mass transfer coefficient problem though. It also doubles the number of unknowns (although you'd only have to add them to pores where reaction occurs, which is usually a subset of the total).

Idea 3: Dual networks

If you use a dual network, then all pores are connected to a 'solid' node already, and the reaction could happen in the solid nodes. This is similar to the fictitious node approach but is a bit more physical.