Out-of-Plane Radiation
Out-of-plane heat transfer mechanism is used to reduce a model geometry to 2D or even 1D when the temperature variation is small in one or more directions; for example, when the object to model is thin or slender. This node models surface-to-ambient radiation on the upside and downside for the obtained 1D and 2D components. It adds the following contribution to the right-hand side of Equation 6-8 or Equation 6-9:
Upside Parameters
Surface Emissivity
The default Surface emissivity εu (a dimensionless number between 0 and 1) is taken From material. For User defined, it should be specified. An emissivity of 0 means that the surface emits no radiation at all, while an emissivity of 1 means that it is a perfect blackbody. The default is 0.
Ambient Temperature
For User defined, enter a value or expression for the Ambient temperature Tamb, u. The default value is approximately room temperature, 293.15 K (20ºC). Else, select an Ambient temperature defined in an Ambient Properties node under Definitions.
Downside Parameters
Follow the instructions for the Upside Parameters section to define the downside parameters εd and Tamb, d.
The Out-of-Plane Radiation feature is disabled when at least one of the multiphysics couplings (Heat Transfer with Surface-to-Surface Radiation, Heat Transfer with Radiation in Participating Media, Heat Transfer with Radiative Beam in Absorbing Media) is active while solving on the same domain. This is noticed through a warning node displayed under Compile Equations. The radiation interfaces assume an infinite medium in the out-of-plane direction, they are thus not compatible with these features.
Out-of-Plane Heat Transfer
Upside and downside settings can be visualized by plotting the global normal vector (nx, ny, nz), that always points from downside to upside. Note that the normal vector (ht.nx, ht.ny, ht.nz) may be oriented differently.
See Tangent and Normal Variables in the COMSOL Multiphysics Reference Manual.
Out-of-Plane Heat Transfer for a Thin Plate: Application Library path Heat_Transfer_Module/Verification_Examples/thin_plate
Location in User Interface
Context Menus
 Heat Transfer in Solids and Fluids>Out-of-Plane>Out-of-Plane Radiation
Heat Transfer in Porous Media>Porous Medium>Fluid>Out-of-Plane Radiation
Heat Transfer in Porous Media>Porous Medium>Porous Matrix>Out-of-Plane Radiation
Ribbon
Physics tab with interface as Heat Transfer in Solids and Fluids, or any version of the Heat Transfer interface selected:
Domains>interface>Out-of-Plane Radiation
Physics tab with Porous Medium>Fluid or Porous Medium>Porous Matrix selected in the model tree:
Attributes>Out-of-Plane Radiation