Thermal adaptive implicit method: Time step selection

Finally, the criterion for the numerical stability of the temperature is divided into convection and conduction parts. Detailed testing using several simulation models shows clearly that the conduction part of the criterion is quite important across the parameter space of practical interest. Thus, in order to simulate the flow dynamics of large, thermal-compositional reservoir models, the conduction term should always be discretized implicitly, and the TAIM stability criteria should be applied to the mass conservation equations and the convection terms in the energy balance. This means that temperature, like pressure, is an unknown variable in every gridlock.