EM Thermal Co-Simulation

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Giles Nelson
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1 CST STUDIO SUITE 2008 Application and Feature Tutorial EM Thermal Co-Simulation Workflow -Material Settings -Boundaries -Losses Examples 1 ube / v1.0 / 14. Sep 2007

2 Steps for EM-Thermal Co- Simulation 1. Choose Template Thermal Cosimulation to activate intersection check 2. Define thermal material properties and boundaries 3. Define E- and H-field monitors for surface and volume losses. 4. Start HF Simulation. 5. Switch to Thermal Problem Class. 6. Define Thermal Sources in CST EMS. Perform the Temperature Simulation. 2

3 Problem Type Thermal only thermal specific sources are shown in iconbar and Solve pulldown menu load loss distribution from other EM Solver 3

4 Problem Type Thermal Only problem type specific items are shown Results are always visible Currently active problemtype 4

5 Thermal Material Properties For any material (incl. background!) the correct thermal conductivity has to be defined. 5

Thermal Intersection check For EM Simulation PEC materials always get

However, in the thermal solver, both PEC and dielectric are typically type

The thermal interaction flag checks, if all objects are properly intersected.

6 Thermal Intersection check For EM Simulation PEC materials always get priority over dielectrics, when overlapping no boolean operation required However, in the thermal solver, both PEC and dielectric are typically type normal (finite thermal conductivity) and have to be intersected. The thermal interaction flag checks, if all objects are properly intersected. This flag has to be activated before EM solver starts. Template is added for conveniance. Objects 6

HF-Thermal coupling Thermal material properties

calculation domain (symmetries, open add space)

7 HF-Thermal coupling Thermal material properties and thermal boundary conditions may be changed without deleting HF-results. Exception: Boundary conditions that change the calculation domain (symmetries, open add space) still delete all results. 7 Fahrenheit, Celsius and Kelvin as units are supported

8 Thermal Boundaries and Symmetries In waveguide port planes as well as for magnetic Symmetry Planes, typically adiabatic should be chosen 8

Activate CST MWS losses as thermal sources During S-Parameter Simulations MWS monitors are normalized to 1W peak (=0.5 W rms) input power at the port.

9 Activate CST MWS losses as thermal sources During S-Parameter Simulations MWS monitors are normalized to 1W peak (=0.5 W rms) input power at the port. This factor allows scaling to the real applied input power. Examples: 5 W rms factor = W rms factor = mW rms factor = Applies volume and surface losses calculated by the E and H Fields from CST MWS as thermal sources. (volume loss requires E- or J-monitor, surface loss requires H-monitor) new in 2008: also losses from dispersive dielectrics and dielectric tan(delta) are considered in thermal volume losses

10 CST MWS normalization of result values 1) S-Parameter Simulations: 1W peak input power 2) Eigenmode Simulations: 1J total stored energy in mode 3) plane wave simulations: specified electric field amplitude (peak value) 4) discrete voltage or current port: specified current/voltage amplitude (peak value) simultaneous port excitations / combine results: final norming results by multiplying the given amplitudes with the above scaling (1-4) 10

Internally this is represented by a lossy surface boundary condition,

11 Convection + Radiation losses Convection- and radiation-properties can be assigned to a chain of faces. Internally this is represented by a lossy surface boundary condition, which is temperature dependent. Radiated power: q R = σ (T-T back ) 4 Area with: σ = σ r σ SB σ r : Emissivity

12 Thermal HEX solver Thermal losses caused by electric currents can be used as a driving source for a thermal problem (HF + LF and Stationary currents) Stationary current field Temperature distribution 12

13 Heat Flow source values logfile 13

- Depending on the field distribution in the cavity the hot spots can be easily

14 Microwave oven from Delonghi -Food model has a small variation of eps with the temperature -The results show where the food absorbed more EM-energy. - Depending on the field distribution in the cavity the hot spots can be easily identified -We thank Dr. Ruggero Roccari and Dr. Sergio Serena from Delonghi for their work on the test case 14

15 Voxel import including thermal properties Low or High Frequency losses can be used as a heat source. HUGO model automatically has electrical and thermal properties defined. 15

16 Particle Thermal coupling Trajectory Temperature 16 Particles hitting metal produce loss distribution Particles loss distribution can be used as a source for the thermal solver

17 Summary / Outlook Thermal Solver is able to read power sources from: CST MWS Monitor, calculated by T or F hex solver CST MWS - Eigenmode CST EMS - LF solver CST PS - absorbed power by hitting particles simplified user handling (materials / boundaries) near future: transient thermal solver 17

18 Outlook Transient Thermal Simulation Induction Cooker 18

Tracking. Particle In Cell. Wakefield

Tracking. Particle In Cell. Wakefield CST PARTICLE STUDIO STUDIO SOLVERS & APPLICATIONS 1 www.cst.com Mar-09 CST PARTICLE STUDIO Solvers Tracking Simulation of DC Particle Guns, Collectors, Magnets Tracking in static E/H fields (incl. space