Add Volume Boundary Condition¶

Introduction¶

Conduction Volume Boundary Conditions are used to impose thermal source terms throughout a finite volume within a conducting solid. Unlike surface boundary conditions, which apply thermal constraints only along a surface, conduction volume boundary conditions act over a three-dimensional region of the conduction geometry. These volume conditions can be used to enforce a fixed temperature throughout a specified region, apply a volumetric heat generation or heat absorption term, or represent internal heaters. Because the condition is applied volumetrically, it influences all computational cells contained within the selected region rather than only affecting the boundary faces of the conduction geometry.

These boundary condition surfaces can be defined either importing a child geometry that overlaps a sub volume of the conducting solid. Once imported, at least one Internal Point must be added to define interior conduction points that identify where the boundary volume is active. Multiple volume boundary conditions can be applied across different regions of the static body geometry.

Access¶

When you select Add Conduction Volume BC on the Static Body Conduction context-specific toolbar, a new child geometry is formed and the property grid below will launch.

Property Grid¶

`General`¶

Boundary Condition

This defines the type of thermal boundary condition applied to the surface conduction region. Options include a user-defined boundary condition temperature or a user-defined heat flux.

Temperature

This defines the system-level temperature UDF used for the boundary condition.

Temperature UDF: K | This defines a custom temperature boundary condition through a user-defined function. This is a System UDF.

Uniform Heating

This defines the system-level heat flux UDF used for the surface boundary condition. This can be specified as either a total applied heat rate or an applied heat flux. In both cases, the boundary condition is applied uniformly across the surface. In all cases, the heating is converted into a flux.If the Flux Specification is set to Total, this value will be divided by the local solid surface area to define a local flux field boundary condition along the solid surface. This is a System UDF.

Heating Specification

This defines how the uniform heating rate is specified.

Total: This specifies the total heat flow rate applied to the static body. At runtime, this value is divided by the computed static-body surface area to determine the equivalent uniform heat flux.
Per Unit Area: This specifies the heat flux directly. This value is applied uniformly over the static-body surface.

Heat Flux UDF

W or W/ \(m^3\) | This UDF defines the heat flux along the surface of the conduction surface body. One output must be defined within the UDF: a floating point variable named value. This output variable defines the heat flux at the along the surface boundary condition. This value can be specified as either a total flux (flow) or aerial flux (per unit surface area).

If the Custom Flux Specification is set to Areal, this value will be used directly in the code to define a local flux field boundary condition along the solid surface. If the Flux Specification is set to Total, this value will be divided by the local solid surface area to define a local flux field boundary condition along the solid surface. This is a System UDF.

Local Heat Flux

This defines a spatially varying heat flux along the static body surface. Unlike Uniform Heating, this option allows the local heat flux to vary as a function of local fluid conditions and position along the wall.

This capability is useful for implementing custom convective heat transfer models where the local heating or cooling rate depends on nearby fluid properties such as temperature, velocity, turbulence, species concentration, or other user-defined quantities.

Heat Flux UDF

W/ \(m^2\) | This UDF defines the local heat flux along the surface of a static body. One output must be defined within the UDF: a floating point variable named qDot. This output variable defines the heat flux at the solid/liquid interface This is a Local UDF, calculated on a voxel-by-voxel basis.

Download Sample File: Isosurface Contour

If Internal Points are added, the following section will launch:

`Internal Points`¶

Point: m | This is the location of the internal fill points added to the volume surface boundary condition. Points are added to the Volume Boundary Condition component using the Add Internal Point tool. This point needs to be inside the child geometry associated with the Volume Boundary Condition.

Location¶

cond Static Body Conduction

Volume Boundary Conditions Toolbar¶

Context-Specific Toolbar Forms	Description
Add Geometry	The Add Geometry form adds child geometry by importing from external CAD files, extracting from external CAD assemblies, or defining internally using built-in parametric geometry.
Move	The Move form enables three-dimensional rigid body transform of object through free drag or point-to-point snapping.
Rotate	The Rotate form enables three-dimensional rotation of geometry.
Scale	The Scale form enables volumetric scaling of a geometry about a set anchor point.
Mate	The Mate form allows surface-to-surface mating and alignment.
Add Internal Point	The Add Internal Point tool is used to add or edit internal points associated with static body condition or conduction volume boundary conditions.
Help	The Help command launches the M-Star reference documentation in your web browser.