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laserHeatSource

Description

This heat source model is used to simulate the heating due to energy deposition from an impinging laser on one of the surfaces of the domain. The model initialize a volScalarField for the laser intensity, called \(I\).

To compute the energy deposition in the domain, the model solves the following radiation attenuation equation:

\[ \begin{aligned} \nabla \cdot (I \vec{n}) + \alpha I = 0 \end{aligned} \]

where:

  • \(I\) is the radiation intensity \(\left(m^{-2}s^{-1}\right)\);
  • \(\vec{n}\) is the beam's direction unit vector;
  • \(\alpha\) is the material absorption coefficient \(\left(m^{-1}\right)\).

Once the model computes the spatial distribution of \(I\), the resulting power density distribution \(Q\) as:

\[ \begin{aligned} Q = I \cdot \alpha \end{aligned} \]

\(\alpha\) is the absorption coefficient of the fully-dense material. However, the code allows to take into account variation in local porosity of the material that can affect its absorption capabilities. This is done through an effective absorption coefficient \(\alpha_{eff}\) that is computed as:

\[ \begin{aligned} \alpha_{eff} = \alpha \cdot \frac{1-p}{1+0.5p} \end{aligned} \]

where:

  • \(p\) is the fractional local porosity of the material.

Options

The laserHeatSource heat source model requires the user to specify a few additional parameters in the heatSourceOptions sub-dictionary located within the solverDict.

Parameters in heatSourceOptions:

alphaAbsorption The absorption coefficient of the material in \(m^{-1}\) .
beamDirection A vector that specifies the direction of the laser beam.
useEffectiveAlpha A bool that specifies whether or not the effective absorption coefficient should be used.
materials A list of material (or cellZones names) where the heat source model applies.

Usage

Here is a code snippet of the solverDict to be used for the laserHeatSource heat source model:

heatSource laserHeatSource;

heatSourceOptions
{
    useEffectiveAlpha   on;
    alphaAbsorption     1e4;
    beamDirection       (0 0 -1);

    materials   (fuel);
}