Add a Domain Sources node to define the mass source, and momentum and energy source types. This domain feature adds the right-hand side 
Sc, 
Sm, and 
Se to the governing 
Equation 5-1 defined through different options
 
    where M is a mass source, A is an acceleration source, 
F is a volume force source, 
prc is a pressure rate of change source, and 
Q is a volumetric heat source. Notice that the mass source term enters both the momentum and the energy equations in a consistent way. The 
Domain Sources can be used to create any user defined source by entering expressions into the fields. The sources can for example be point-like Gaussian sources to model an idealized single vortex or two interacting vortices.
 
    Select a Momentum source type: 
Acceleration (the default) or 
Volume force. For 
Acceleration enter vector expressions or values for the 
Acceleration source A (SI unit: m/s
2). For 
Volume force enter vector expressions or values for the 
Volume force source F (SI unit: N/m
3).
 
    Select an Energy source type: 
Pressure rate of change (the default) or 
Heat source. For 
Pressure rate of change enter an expression or value for the 
Pressure rate of change source prc (SI unit: Pa/s). For 
Heat source enter vector expressions or values for the 
Heat source Q (SI unit: W/m
3).