6.2.13                    Time integration of the Poynting vector

QuickWave allows for monitoring the time-integrated Poynting vector in a particular part of space. This is available in the ExH Time Integral post-processing. The monitoring is performed in all areas defined as FD Monitors (see User Guide 3D: Application of Frequency Domain Monitors (FDM) for microwave heating for more information on how such monitors are defined) thus, this post-processing can be activated only when at least one FD Monitor is defined. Time domain integral of the Poynting vector has the meaning of a power flux and is expressed in [J/m²]. This value is typically compared to the total energy available from the input pulse source and that is why this post-processing should be used together with the Power Available post-processing, which provides information about the spectrum of the input pulse  and the total energy available in it. It should be noted that when the ExH Time Integral post-processing is active, QW-Simulator will start integrating the Poynting vector components over time starting from the first iteration and will indicate it in the Simulator Log window by a line like "Postprocessing [2]: fdm3d_1, (ExH Time Integral): Components: Sx Sy Sz, Sparsity: X=1 Y=2 Z=3".

When configuring the ExH Time Integral post-processing in the Input Interface, the user may choose which of three Poynting vector components will be integrated: Sx, Sy, Sz. It should be also noted at this point that the integration is relatively time consuming and thus in big scenarios it is recommended to use this post-processing with a reduced space resolution obtained by application of appropriate sparsity factors, set when configuring the ExH Time Integral post-processing in the Input Interface.

Attention: The ExH time integral is calculated in the area defined by the FD Monitor but it does not include calculation of Fourier transformation in time. For that reason its results in QW‑Simulator are displayed using Poynting function in 2D/3D Fields tab instead of using Monitor tab, as for FD Monitors. The results of Poynting vector integration over time are available as òS, òSx, òSy, and òSz components.

The application of ExH Time Integral post-processing in practice is discussed in User Guide 3D: Application of ExH Time Integral for microwave heating.