For all flows, Ansys Fluent solves conservation equations for mass and momentum. For flows involving heat transfer or compressibility, an additional equation for energy conservation is solved. For flows involving species mixing or reactions, a species conservation equation is solved or, if the non-premixed combustion model is used, conservation equations for the mixture fraction and its variance are solved. Additional transport equations are also solved when the flow is turbulent.

In this section, the conservation equations for laminar flow in an inertial (non-accelerating) reference frame are presented. The equations that are applicable to moving reference frames are presented in Flows with Moving Reference Frames. The conservation equations relevant to heat transfer, turbulence modeling, and species transport will be discussed in the chapters where those models are described.

The Euler equations solved for inviscid flow are presented in Inviscid Flows.