Freezing TH solutions to allow for focused scalar transport in linear PIMPLE solver

[mtnwalker]

Motivation

This would allow for users to load in an existing steady TH solution (pressure, energy, velocity fields) and then perform scalar transport only simplifying the and accelerating species only transport calculations.

Design

One method this could be implemented is to solve for the TH fields from the exodus restart for time less than 1. Afterwards these TH variables would be skipped and the passive scalars can be solved using the 'frozen' TH fields.

Impact

This would allow for users to load in an existing steady TH solution (pressure, energy, velocity fields) and then perform scalar transport only simplifying the and accelerating species only transport calculations.