# Global Commands

This chapter contains the commands that define the global description of a problem or provide data that can be used globally.

This chapter contains the commands that define the global description of a problem or provide data that can be used globally.

**EQUATION**

Specifies the equation systems present in the problem.**FLOW_FIELD**

Specifies the flow field used in the problem.**USER_EQUATION**

Specifies a user equation in the problem.**COUPLING_FIELDS**

Specifies which AcuTrace fields couple with AcuSolve and how they couple when flow_field_type is two_way_coupling.**FINITE_MASS**

Specifies the finite mass model parameters.**FINITE_MASS_BOUNDARY_CONDITION**

Specifies the finite mass boundary conditions and interaction parameters for a particle surface.