1.1     Frequently asked questions

Below we summarise the answers to frequently asked questions about QW-BHM. These answers also indicate known current limitations of QW-BHM. The users interested in alleviating any of these limitations are encouraged to contact QWED. We shall be expanding QW-BHM functionalities in response to the users’ requests.

1.     Which media types are and which are not heated in QW-BHM regime?

The only heated media are dielectric isotropic or dielectric anisotropic type. Metals (PEC or Metallic) are not heated during the simulations – power generated in lossy metals is added to the neighbouring dielectric region. Dispersive media (Dielectric dispersive, Metamaterial, Ferrite) can be included in the scenario, but the power dissipated therein is calculated with an approximate formula, using constant conductivity. For Drude and Lorentz dispersion, this effective conductivity is equal to Sigma and SigmaM settings of QW-Editor; for Debye it is modified partially accounting for series losses. Thus dissipated power, enthalpy and temperature patterns in dispersive media are only approximate. Moreover, these media parameters cannot be changed as a function of temperature. Power dissipated in lumped elements is not calculated and the values of these elements cannot vary with temperature.

2.     Which parameters prevail in the case of conflicting settings of Parameters-Media in QW‑Editor and the *.pmo files?

The *.pmo files always take precedence over the default settings of QW-Editor. Moreover, QW-HFM does not consider QW-Editor settings at all, and requires all thermal media parameters to be defined in *.pmo and *.pm2 files, as explained in Defining of media properties.

3.     Are all QW-BHM regimes mutually compatible?

All BHM regimes are mutually compatible and can be used jointly, for example: rotation+tuning; rotation+heat flow, rotation+tuning+heat flow.

4.     Can Freeze operation be performed on BHM scenarios?

Freeze operation can be applied to all BHM scenarios excluding scenarios with frequency tuning (automatic and manual). However, it can only be invoked during regular FDTD iterations - not during the actual BHM processing. The *.sfr file contains current electromagnetic fields, enthalpy, and temperature as well as copies of all the files needed for restoring the simulation, including *.pmo, *.mv3, *.ro3, *.pa3, *.sh3 and *.ta3 files.

5.     In what circuit types can the BHM regime be used?

QW-BHM has been designed for 3D and V2D (BOR) circuit types. Its compatibility with 3DP (periodic) circuits has not been tested.

6.     Which QuickWave software modules cannot be used jointly with QW-BHM?

QW-BHM cannot be used with QProny and QW-OptimiserPlus. QW-BHM can be configured in QW-Editor and also (rotation only) directly in the Autodesk® Inventor® Software with QW-AddIn for Autodesk® Inventor® Software module and can be used with QW-Simulator GPU (massive parallel version of QW-Simulator).

7.     Can QW-BHM scenarios be prepared with Amigo option of QW-Editor?

QW-BHM scenarios without load rotation can be prepared with the Amigo option without any restrictions. The rotated scenarios require cautious use of Amigo, as explained in point 8 below.

8.     What are the restrictions on preparing BHM scenarios for load rotation analysis?

QW-BHM assumes that meshing (or, strictly speaking, coordinates of mesh lines) does not change during rotation. Thus, the object being rotated cannot include explicit mesh snapping planes of variable position. Also, all elements within this object must be disabled for Amigo, to avoid automatic generation of variable mesh snapping planes (by hard, soft and weak edges and corners) and mesh density adjustment to permittivity and permeability of the moving load. Disabling can be done by checking Disable box in the Element Change dialogue of QW-Editor or by UDO command SETATTR.

9.     What limitations apply to boundary conditions in QW-HFM?

QW-HFM in the FDTD mode uses three types of boundary conditions described in QW-HFM external module and QW-HFM internal module: explicit, adiabatic, and convective. In the Fluent mode of operation, the use of convective condition is limited to external boundaries of the analysed thermal scenario; internal convective boundary conditions (as defined through *.pm2 files, see Defining of boundary conditions, are not supported in the Fluent mode of QW‑BHM.

10.  Are QW-BHM results dependent on the choice of 32-bit or 64-bit implementation?

The results of QW-BHM results obtained with 32-bit and 64-bit versions may differ due to the different accuracy of arithmetic operations. Typical results of QW-BHM, such as local temperature patterns over the FDTD mesh, tend to be more sensitive to arithmetic round-off errors than typical results of pure electromagnetic simulations, such as S-parameters, with provide global and naturally averaged information about the modelled scenario.

The 64-bit version of QW-BHM has been used in preparing most of the examples discussed further throughout this manual.

The external QW-HFM module is available in the 32-bit implementation only.

The internal QW-HFM module, fully integrated with QW-Simulator, is available in the 32-bit and 64-bit implementations. The internal QW-HFM module is accelerated using multiprocessor/multicore OpenMP standard (within QW-Simulator OMP). The internal QW-HFM module is used by default in the BHM scenarios (see The initialisation file for more details).

11.  Which columns of *.pmo files are mandatory in QW-HFM operation?

Refer to Defining of the media properties.