# BODY_FORCE

Specifies a collection of volumetric body force terms.

AcuSolve Command

## Syntax

BODY_FORCE("name") {parameters...}

User-given name.

## Parameters

gravity or grav (string)[=none]
User-given name of the gravity command. If none, no gravity is included.
rotation_force or rot (string) [=none]
User-given name of the rotational force command. If none, no rotational force is included.
mass_heat_source (string) [=none]
User-given name of the heat source per unit mass command. If none, no mass heat source is included.
momentum_source (string) [=none]
User-given name of the momentum source command. If none, no momentum source is included.
volume_heat_source (string) [=none]
User-given name of the heat source per unit volume command. If none, no volume heat source is included.
mass_species_1_source (string) [=none]
User-given name of the species source per unit mass command for the species 1 equation. If none, no mass species source for the species 1 equation is included.
mass_species_2_source (string) [=none]
User-given name of the species source per unit mass command for the species 2 equation. If none, no mass species source for the species 2 equation is included.
mass_species_3_source (string) [=none]
User-given name of the species source per unit mass command for the species 3 equation. If none, no mass species source for the species 3 equation is included.
mass_species_4_source (string) [=none]
User-given name of the species source per unit mass command for the species 4 equation. If none, no mass species source for the species 4 equation is included.
mass_species_5_source (string) [=none]
User-given name of the species source per unit mass command for the species 5 equation. If none, no mass species source for the species 5 equation is included.
mass_species_6_source (string) [=none]
User-given name of the species source per unit mass command for the species 6 equation. If none, no mass species source for the species 6 equation is included.
mass_species_7_source (string) [=none]
User-given name of the species source per unit mass command for the species 7 equation. If none, no mass species source for the species 7 equation is included.
mass_species_8_source (string) [=none]
User-given name of the species source per unit mass command for the species 8 equation. If none, no mass species source for the species 8 equation is included.
mass_species_9_source (string) [=none]
User-given name of the species source per unit mass command for the species 9 equation. If none, no mass species source for the species 9 equation is included.
volume_species_1_source (string) [=none]
User-given name of the species source per unit volume command for the species 1 equation. If none, no volume species source for the species 1 equation is included.
volume_species_2_source (string) [=none]
User-given name of the species source per unit volume command for the species 2 equation. If none, no volume species source for the species 2 equation is included.
volume_species_3_source (string) [=none]
User-given name of the species source per unit volume command for the species 3 equation. If none, no volume species source for the species 3 equation is included.
volume_species_4_source (string) [=none]
User-given name of the species source per unit volume command for the species 4 equation. If none, no volume species source for the species 4 equation is included.
volume_species_5_source (string) [=none]
User-given name of the species source per unit volume command for the species 5 equation. If none, no volume species source for the species 5 equation is included.
volume_species_6_source (string) [=none]
User-given name of the species source per unit volume command for the species 6 equation. If none, no volume species source for the species 6 equation is included.
volume_species_7_source (string) [=none]
User-given name of the species source per unit volume command for the species 7 equation. If none, no volume species source for the species 7 equation is included.
volume_species_8_sourcenone (string) [=none]
User-given name of the species source per unit volume command for the species 8 equation. If none, no volume species source for the species 8 equation is included.
volume_species_9_source (string) [=none]
User-given name of the species source per unit volume command for the species 9 equation. If none, no volume species source for the species 9 equation is included.

## Description

This command specifies a collection of volumetric body forces.
Note: ROTATION_FORCE is an obsolete command and will be removed eventually. Instead, REFERENCE_FRAME should be used for rotational forces.

BODY_FORCE commands collect

• GRAVITY
• ROTATION_FORCE
• MASS_HEAT_SOURCE
• MOMENTUM_SOURCE
• VOLUME_HEAT_SOURCE
• MASS_SPECIES_SOURCE
• VOLUME_SPECIES_SOURCE
commands by referencing their user-given name. The BODY_FORCE commands are in turn referenced by ELEMENT_SET commands. For example,
GRAVITY( "my gravity" ) { ... }
ROTATION_FORCE( "my rotation force" ) { ... }
MOMENTUM_SOURCE( "my momentum source" ) { ... }
MASS_HEAT_SOURCE( "my heat source" ) { ... }
MASS_SPECIES_SOURCE( "my species source 1" ) { ... }
MASS_SPECIES_SOURCE( "my species source 2" ) { ... }
BODY_FORCE( "my body force" ) {
gravity = "my gravity"
rotation_force = "my rotation source"
momentum_source = “my momentum source”
mass_heat_source = "my heat source"
mass_species_1_source = "my species source 1"
mass_species_2_source = "my species source 2"
mass_species_3_source = "my species source 1"
}
collects all source terms which in turn may be referenced by one or more element sets:
ELEMENT_SET( "fluid with body forces" ) {
body_force = "my body force"
...
}

For backward compatibility with AcuSolve version 1.6 and earlier, heat_source may be used instead of mass_heat_source and species_1_source may be used instead of mass_species_1_source, and so on. However, these aliases are obsolete and will be deprecated in the future.

Both mass_heat_source and volume_heat_source may be specified in a single BODY_FORCE command. Similarly, both mass and volume versions of the species source terms may be specified simultaneously. The appropriate terms are simply added together. However, this usage is not recommended.