Thermal-centric Modeling

It seems like almost every simulation software company offers “heat transfer analysis” or “thermal analysis.”

We do too. We are thermal engineers making the tools we want to use, which means we understand the questions you need to answer and the problems you face.

So we go beyond “thermal analysis” to bring you Thermal-centric Modeling. We bring you specialized tools for thermal engineers that you won't find elsewhere.

What is thermal-centric modeling, and what distinguishes it from “thermal analysis?”

Just solving for temperatures isn’t enough.

Temperature profiles within the wall of a fluid container can provide boundary conditions for a CFD run, but where did those profiles come from? Do they take into account the often complex thermal boundary conditions outside the container? What about the pressures and velocities and temperatures at inlets and outlets? What assumptions were made in order to divorce this subset analysis from the full system?

Similarly, temperature contours within a complex solid part are necessary for thermoelastic structural analysis, but can those contours be trusted if they are based on overly-simplified boundary conditions?

Thermal-centric modeling doesn’t stop at part boundaries. In fact, it often starts there.

Radiation, contact, and convection all happen at the outer surfaces of a part, but getting the total surface area right is just the beginning.

Thermal radiation at the surface depends on interactions with everything the part can “see,” and thanks to reflections, this isn’t restricted to line-of-sight. Thermal-centric modeling includes fast-solving radiation calculations for complex environments at the assembly or system level.

Contact between parts isn’t something that can be characterized with a simple flux or a constant temperature. Just like radiation, it requires higher-level assemblies to be analyzed. But contact conduction also adds new twists, including a fundamentally high level of uncertainty. Thermal-centric modeling tools understand that pre-test analysis must be able to bracket that uncertainty safely; post-test models must be calibrated automatically; and, for high-volume products, tools must be available for modeling manufacturing variations in materials and contact pressures.

In thermal modeling, you want the mass of a part to be correct. You want the surface area to be correct. But you don't want to "waste nodes" solving the details within a part since you almost always need to solve at a high level of assembly.

Steady-state is an assumption, not a feature.

Time doesn’t stand still, unless we assume it does. Design verifications in the real world often require transient (dynamic) analyses, and lots of them: start-ups, shut-downs, control system interactions, mission scenarios. When does a circuit board overheat or the fuel stratify and freeze? What time does the compressor torque peak, or when is the dew point temperature reached?

One or two transient runs rarely address any real-world design issues. Thermal-centric modeling means being able to make hundreds or thousands of runs as needed to handle variations in environments and uncertainties. And thanks to radiation, convection, and contact conduction, those variations are important only at a system-level where the heat flow pathways between  many parts becomes important.

Balancing heat flows requires a system-level focus.

What is your “system?” It probably isn’t a coldplate or a piston head. It is more likely an engine or an airplane.

Steady-state temperature profiles within a solid part aren’t enough. Fast-solving tools for vehicle-level or product-level transient analysis are needed if you want to be able to track energy as it flows in, out, and through your system.

If your system is in the early design stages, you need the ability to rapidly sketch prototype geometry, or even analyze at a lumped-parameter level. If the design is in the later stages of development, you need to be able to start with CAD drawings of parts, and easily simplify them for a system-level focus without being a CAD expert. And you need to be able to update your models quickly to keep up with a fast-moving project that makes last minute changes.

Uncertainty dominates our world. Until it doesn't.

  • Contact conductance. You can guess within 50%.
  • Natural convection. Hopefully plus or minus 25%. On a good day.
  • Two-phase pressure drops. Where else would you consider 20% to be "very accurate?"

Our world is dominated by uncertainties. If we're at the early stages of design, we are used to designing conservatively: bracketing worst cases if we must, and estimating design risk if we can.

If that were the end of the statement, thermal engineering wouldn't exist. It would be a waste of time.

Fortunately (for thermal designers!), testing is expensive. Very expensive, especially when you consider you can't possibly test all combinations of environmental, mission scenario, and manufacturing uncertainties.

You need tools that are designed to help you navigate uncertainties in the early design stages. Tools that are not only completely parametric, but also have built-in statistical sampling and that can seek worst-case scenarios.

You also need tools that can make the most of any test data you can find or afford to generate. After all, a few tests can reduce uncertainties in our traditional demons (contact conductance, natural convection, two-phase coefficients, etc.) to within a few percent. Once calibrated, we can extrapolate to all the cases we can't test.

And that's why we're invited to participate in the next design!

CRTech: Home of Thermal-centric Modeling

  • Focus on system-level analyses in the time domain (transient, dynamic)
  • Best-in-class thermal radiation solution
  • Contact conduction in complex assemblies
  • From lumped parameter to finite difference to CAD-based FE model generation
  • Special-purpose curved elements: avoid over-meshing without sacrificing mass or surface area
  • Reduced thermal dimensions: "thermally thin" shells that are "thick" for contact and radiation
  • Cycle-level thermohydraulics
  • System-level heat pipe tools
  • System-level or detailed-level heat exchanger analysis
  • Cycle-level turbomachinery, or detailed (secondary flows)
  • Equilibrium subset mixtures for fast simulation of reacting flows (finite rate also available)
  • Filling and emptying complex fuel and cryogenic tanks without CFD
  • Variational analysis:
    • scaling factors
    • parameterization and sensitivity analysis
    • optimization
    • automatic model calibration to data
      • Define thermocouple locations, point to test data
    • uncertainty analysis and worst-case seeking

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