Incident Intensity (Radiative Beam in Absorbing Medium Interface)

Use this node to specify an incident radiative beam on the boundaries of an absorbing medium. The incident beam is defined from its propagation direction and incident intensity. See Absorbing Medium (Radiative Beam in Absorbing Medium Interface) for the modeling of the beam absorption in the medium.

Boundary Selection

Select the boundaries on which to apply the incident beam. The radiative intensity corresponding to the incident beam will be defined on any selected boundary such that the dot product between the beam orientation and the outgoing normal vector from the physics interface selection is negative.

Model Input

This section has fields and values that are inputs to expressions that define material properties. If such user-defined property groups are added, the model inputs appear here.

Beam Orientation

Enter values for the e. The orientation vector does not need to be normalized.

BEAM Profile

Either set the as by entering a value for the , I0 (SI unit: W/m2), or select an option among the . The list provides the following options: (the default) or .

Enter a value for the P0 (SI unit: W) and the O (SI unit: m).

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For , enter the σ (SI unit: m).

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For , enter the R (SI unit: m). Smoothing can be applied by entering a positive ΔR (SI unit: m). The default value of 0 m corresponds to an ideal discontinuous top-hat profile.


	This feature does not account for shielding effect between multiple absorbing media. In addition, a radiative beam leaving an absorbing medium will not generate an incident beam in an absorbing medium placed behind the first one.


	The standard deviation of the Gaussian distribution and the radius of the top-hat distribution can take values smaller than the mesh element size. For more accurate results, it is important to refine the mesh enough at the heat source location. Otherwise, an automatic substitution replaces the standard deviation σ or the radius R by the minimum length to get acceptable results which depends on the mesh element size.


	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.


	Radiative Beam in Absorbing Media Theory

Location in User Interface

Context menus

Ribbon

Physics Tab with selected: