4.3.1    Defining of the media properties

Using the QW-HFM module in the simulation of a microwave heating problem requires that the user prepares a *.pmo file for each medium which should be taken into account. Objects made of media without a valid *.pmo file will be ignored by the QW-HFM module. An example *.pmo file is shown in Fig. 4.3.1-1.

Fig. 4.3.1-1 An example *.pmo file containing the electromagnetic and thermal properties of pure water.

A valid *pmo file should contain all the columns required by the QW-BHM module for the electromagnetic simulation. Moreover, the user should make sure that the “Ka” (information on the thermal conductivity of the medium) is also provided (or the data-set of Kx, Ky, Kz for anisotropic heat conductivity). Depending on the selected model (linear or nonlinear one), the data on specific heat and density (SpecHeat and Density columns) may be needed or not:

·       In the FDTD (external QW-HFM) and QUICKWAVE (internal QW-HFM) mode with nonlinear model (UseNonlinearModel option active in Preferences dialogue; always active for internal QW-HFM) the SpecHeat and Density columns are not necessary and are ignored. All the data needed for computations are extracted from temperature-enthalpy curve and the Ka column (or Kx, Ky, Kz columns for thermally anisotropic media). Both temperature and enthalpy columns are therefore necessary in media *.pmo files.

·       In the Fluent mode with nonlinear model the SpecHeat column is also ignored as it can be extracted from temperature-enthalpy curve together with the Density data. The data from the Density column – if found – are used by Fluent. Otherwise, the constant density of 1000.0 kg/m³ is assumed while the specific heat data provided to Fluent are modified accordingly. Thanks to these feature medium definitions closely match the contents of the original *.pmo files.

·       If the linear model is used (in both FDTD and Fluent modes) the Temperature, Enthalpy, SpecHeat, Density and Ka (or Kx, Ky, Kz) columns are needed. If either column is not found in the *.pmo file, QW-HFM will signal an error and the heat flow analysis will be aborted. The values of SpecHeat, Density and Ka from the first row (at the lowest temperature listed in the *.pmo file) are taken throughout the analysis.

Settings of density and specific heat made in QW-Editor are ignored by QW-HFM.

QW-HFM module issues a warning if a *pmo file is found for a particular medium, but does not contain all the required columns. It also issues a warning if no *pmo files have been found for the project media, which means that the heat transfer has not been conducted.