Icon Symbolizing Heat Conduction Mechanism with Teapot that is Heated Up

Heat Conduction

  • multi-layered composite shell elements
  • solid elements
  • connectivity elements and thermal contact definitions
  • temperature-dependent material properties
  • anisotropic heat conduction
  • internal heat generation
  • phase-changes

Icon Symbolizing Thermal Convection Mechanism with a Plate, Ventilator and Turbulent Flow

Thermal Convection

  • simple and advanced analytic models for convective heat transfer
  • air zones with degrees of freedom for bulk temperature and humidity
  • user-defined mass & volume transfer
  • ventilation objects to model HVAC systems
  • coupling to external fluid dynamics solver possible
  • coupling to various fluid network solvers via coupling software TISC

Icon Symbolizing Thermal Radiation Mechanism with Solar Collectors and Sun

Thermal Radiation

  • models for solar radiation and all sorts of other sources of light and thermal radiation
  • material properties depending on wavelength and angle of incidence
  • intra-model surface-to-surface radiation
  • considers absorption, reflection and transmission as well as refraction
  • diffuse and specular reflection
  • tool for generating representative solar and cloudiness environmental data for any place and time on earth

Software for Heat Transfer Analysis

The thermal solver at the core of THESEUS‑FE can look back on a successful history of over 30 years. This makes THESEUS‑FE one of the oldest and most mature CAE tools in the field of numerical thermal simulations.

At the center of our software portfolio THESEUS‑FE is the tool chain for thermal analysis simulations suitable for solving a wide range of heat transfer problems. The tools include

  • a highly efficient numerical solver
  • a powerful and intuitive graphical user interface (GUI)
  • the Coupler module to quickly and robustly set up complex coupled simulations with external tools
  • the Transformer utility to convert results of THESEUS‑FE to various other formats as well as preparing field results from other sources as boundary conditions in a THESEUS‑FE case

THESEUS‑FE is always a first-choice candidate whenever the transient thermal development of a component has to be analyzed. The application range of THESEUS‑FE encompasses but is not limited to:

  • simple cases, e.g. heating of individual components for performing virtual thermal endurance studies
  • advanced cases including the heat exchange with human thermal models
  • highly complex simulations fully coupled with external fluid dynamics simulations

Overview of Thermal Analysis features

Image Showing some Formulas related to the Finite Element Method used in THESEUS-FE
Formulas related to the finite element method used in THESEUS‑FE

Core numerical thermal solver

THESEUS‑FE offers a steady-state and transient solver based on the Finite Element Method (FEM) for solving heat transfer problems. Different types of thermal boundary conditions can be applied such as:

  • heat exchange by convection at surfaces
  • thermal radiation between surfaces and external solar loads
  • direct spatial contact of surface areas
  • various types of heat sources and sinks
  • coupling of component part temperatures to adjacent air

Most boundary conditions can be time-dependent or temperature-dependent. For full flexibility the user can import element-wise values from result files.
The numerical solver itself allows for

  • fixed and adaptive time stepping for efficient solution progress
  • restarting a simulation based on previous results
  • a wide range of expert solver options for fine-tuning of result precision and convergence behaviour
Image of Thermal analysis results on Car Driver
Thermal analysis results on car driver

Thermal manikin FIALA-FE

FIALA-FE, a virtual human thermal model based on latest research results in the area of thermophysiology, is included as well. Its purpose is the simulation of the temperature distribution of the human body on the surface as well as internally. Life-like simulations can be performed taking into account aspects as blood flow, respiration, evaporation, metabolic responses, sweating, shivering, cardiac output and local heat exchange between the manikin and its environment. The thermal manikin FIALA-FE is fully integrated in our solver THESEUS‑FE. It is a powerful tool providing both local and global thermal comfort indices. FIALA-FE is commonly used for determining optimal settings for automotive HVAC systems while maintaining passenger comfort. For electric vehicles an additional objective is maximizing vehicle range by reducing the HVAC energy consumption.

Image of Heat Transfer simulation model opened in THESEUS-FE GUI
Heat Transfer simulation model opened in THESEUS‑FE GUI

Graphical User Interface

The easy-to-learn and clearly structured graphics user interface (GUI) of THESEUS‑FE is a highly valuable tool for reducing model building time. To further minimize model setup time, a vast material database including thermal properties of the most common materials is readily available. Default clothing datasets for typical summer and winter clothing settings are available as well. All simulation results are written to a single output file in the publicly documented HDF format which is perfectly suitable for storing numerical results. These simulation results can be visualized within the GUI at any time during and after the simulation. Various ways of displaying and interpreting results are possible, ranging from simple 2d plots to fully-featured 3d views. Results from THESEUS‑FE can be exported or mapped to various formats for use in third-party CAE simulation software and post-processing tools.

Simulate Thermal Conduction

Image of Thermal Results on Brake Disc
Results from heat transfer simulation on brake disc

Simulation of heat transfer by conduction is done within THESEUS‑FE using established Finite Element approaches. The thermal conduction solver offers all features necessary for modelling highly complex cases of thermal conduction:

  • multi-layered composite shell elements with 1D and 3D conduction representing sheet-like parts with uniform thickness
  • solid elements for modelling massive volumes
  • connectivity elements, e.g. bars and DOF coupling constraints
  • temperature-dependent and time-dependent thermal material properties
  • phase changes are possible
  • internal heat generation within shell and solid elements
  • vacuum and air layers within composite shells
  • anisotropic heat conduction, e.g. for representing fibre-reinforced materials
  • various techniques for modelling direct contact between different parts, including tied contact and conductive contact

Simulate Convective Heat Transfer

Image of Coupled Simulation with CFD Results and Thermal Results of Car Cabin including a Driver
Coupled simulation with CFD results and thermal results of car cabin

Thermal convection can be modelled using various means within THESEUS‑FE. For prescribing convective heat transfer, analytical models are available as well as direct user-input to apply heat transfer coefficients, fluid velocities or temperature value for each element individually. Special entities called 'Ventilation', 'Volumes' and 'Airzones' can be used to model ventilation systems and regions of air flow such as vehicle cabins.

For modelling heat transfer by convection, the following features are at hand:

  • general gas regions with temperature-dependent properties
  • special air regions offering bulk temperature and humidity as additional degrees of freedom
  • advanced convection laws for forced and free convection, analytically modelling laminar and turbulent flow
  • user-defined mass/volume transfer between regions of air, e.g. to model exhaust gas systems
  • automatic detection of small, nearly encapsulated regions to simplify the process of assigning suitable convection boundary conditions to all surfaces

Simulate Radiative Heat Transfer

Image of Solar Radiation on Airplane with Passengers
Solar radiation simulation results on airplane

THESEUS‑FE comprises many different mathematical models for representing energy exchange by thermal radiation. The overall spectrum of thermal radiation is separated into two bands, the so-called short-wave and long-wave radiation ranges.

Short-Wave Radiation

The short-wave range includes all wavelengths below the ultraviolet spectrum, the entire spectrum of visible light and higher-frequency parts of the infrared spectrum. This is the typical domain of energy sources dominated by radiative energy exchange, including solar energy, domestic light sources and infrared radiators. This kind of radiation exchange usually takes place in a highly directional manner. Within the radiation solver, material parameters and interaction effects such as specular and diffuse reflection, transmission and absorption can be treated in a physically correct manner as a function of wavelength. Major effects covered by the short-wave radiation solver include:

  • diffuse and specular reflection
  • opaque and transmitting materials
  • transmittance depending on the angle of incidence
  • refraction in transparent materials, e.g. to model optical lenses in automotive headlights
  • wave-length dependent material properties for absorption, transmission and reflection
  • various specialized sources of radiative energy, e.g. to model the sun, point-sources or generally radiating surfaces

Long-wave radiation

The long-wave range is used to model intra-model thermal radiation energy exchange based on the current part temperature. Depending on the temperature, this type of thermal radiation can reach into the visible spectrum but is usually maximal in the non-visible, deep infrared range. The intra-model radiative exchange is modelled in a highly efficient manner using view factors calculated between all the surfaces of the finite element mesh.

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