Why Are Solvers Different From Models?

The essential difference between a solver and a model is that the scope of a model is limited to the continuum in which is defined, while the solver can span continua.

This distinction between solvers and models facilitates the simultaneous solution of physical phenomena across regions that are associated with different continua, such as conjugate heat transfer. The figure below, which shows two continua, illustrates this distinction:

• one region that is called Fluid Continuum, representing a fluid
• one region that is called Solid Continuum, representing a solid

Suppose the following are defined:

• a flow model and a fluid energy model in a Fluid Continuum
• a solid energy model in a Solid Continuum

A solver would be activated in the Fluid Continuum to control the flow solution in that continuum and another solver would be activated in Solid Continuum to control the energy solution. In this situation, a single solver would control two different models (fluid energy and solid energy) in both continua, which allows the implicit solution of the conjugate heat transfer.