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Thermal Solver
Contains thermal solver related guides, such as the TMG reference manual, thermal solver customization guide, and error message list.
Thermal solver theory
Describes the theory and methods of the thermal solver.
Radiation exchange
Thermal radiation is a heat transfer due to electromagnetic radiation emitted by the surface of bodies due to their temperature.
Multiband radiosity method with ray-traced view factors
Ray-traced view factors account for specular reflection and transmission when a model contains specular or transparent surfaces.

Thermal-Flow
Contains general thermal and flow solver related documentation, such as the verification test cases, monthly critical fixes, DMP guide, and knowledge base articles.
Thermal Solver
Contains thermal solver related guides, such as the TMG reference manual, thermal solver customization guide, and error message list.
- Thermal solver guides
  Maya HTT's thermal solver is included in Simcenter 3D and in Simcenter Femap. This page contains links to thermal solver guides, which help you understand how the thermal solver works.
- Thermal solver reference
  Describes the format and contents of the thermal solver's input and output files
- Thermal solver theory
  Describes the theory and methods of the thermal solver.
  - Introduction
    This guide provides the theory and methods used by the thermal solver, including methods to calculate conduction, convection, and radiation, as well as modeling specific topics using the thermal solver.
  - Elements in the thermal solver
    The thermal solver uses elements to calculate conductive, convective, and radiative conductances, as well as hydraulic resistances.
  - Supported element types for radiation
    Radiating elements may be defined with 1 to 4 corner nodes. The elements may be linear or parabolic.
  - Conduction methods
    To model heat conduction, the thermal solver can use two finite volume methods, center of element method or element's center of gravity method, or the finite element method.
  - Convective heat transfer methods
    The thermal solver computes convection conductances for various geometrical configurations using correlations that depend on specified characteristic lengths, convective surfaces, and type of convection.
  - Radiation exchange
    Thermal radiation is a heat transfer due to electromagnetic radiation emitted by the surface of bodies due to their temperature.
    - Basic view factor concepts
    - View factor calculation using deterministic without ray-tracing
    - View factor calculation using deterministic ray-tracing
    - View factor calculation using the hemicube method
      The thermal solver uses the hemicube method to compute diffuse blackbody view factors.
    - View factor calculation using the Monte Carlo method
      The thermal solver uses the CPU-based Monte Carlo algorithm for calculating view factors in radiation modeling using ray-tracing technique when modeling advanced optical properties.
    - Radiative conductance calculation methods
      Radiative conductance defines the rate (W/K) at which thermal radiation is exchanged between surfaces. The thermal solver supports multiple methods for calculating radiative conductance, each suited to different levels of geometric complexity, material properties, and computational constraints.
    - GPU-based radiation calculation methods
      GPU-based calculation methods for radiation exchange use the graphics processing unit (GPU) to perform accelerated radiation computation.
    - Radiation patches
      Radiation patches are used to accelerate the solution of radiative heat transfer.
    - Comparison of radiation calculation methods
      This tables compares different radiation computation methods used for computing radiation exchange in thermal simulations.
    - Radiation enclosures
      The thermal solver separates elements into enclosures. An enclosure is defined to be a set of elements that view each other and only each other.
    - Diffuse reflectivity calculation
      This section describes the calculation of diffuse reflectivity for materials with angle-dependent specular reflectivity or transmissivity.
    - Effective property calculation
      For each element, the thermal solver calculates the effective properties from the surface properties and self-view factors.
    - Heat flux calculation in radiative heat transfer
      The thermal solver computes the incident, reflected, absorbed, and transmitted energy fluxes for radiative heat transfer analysis.
    - Plane stress view factor calculation when modeling with axisymmetric or 3D elements
      This section explains how the thermal solver computes the view factor for axisymmetric or mixed 2D axi-3D models with plane stress elements for radiation requests.
    - Multispectral band radiation analysis
      The thermal solver converts wavelength-dependent thermo-optical properties into equivalent values for each spectral band to use in radiative heating and radiation exchange calculations.
    - Multiband radiosity method
      The multiband radiosity method calculates infrared exchange by integrating wavelength-dependent radiative quantities over spectral bands.
    - Multiband radiosity method with ray-traced view factors
      Ray-traced view factors account for specular reflection and transmission when a model contains specular or transparent surfaces.
  - Solar heating
  - Steady state analysis
    In a steady state analysis, the thermal solver solves the temperatures of non-sink elements iteratively using the following algorithm.
  - Transient analysis
    Transient analysis is performed using the following algorithm.
  - Hydraulic network analysis
    When the hydraulic pressure-flow network is present in the model, the thermal solver solves it at each iteration or time step using the following algorithm.
  - Miscellaneous topics
  - Thermal solver theory bibliography
    The following bibliography lists all sources used to explain how the thermal solver works.
- Thermal solver customization
  Allows you to create or add functionality to enhance the thermal solver capabilities.
- Thermal solver error message list
  Lists solver messages that the thermal solver generates to communicate issues with the model or the solve.
Flow Solver
Contains flow solver related guides, such as the reference and customization guides.
TMG Critical Fixes
Maya HTT strives to release the best thermal-flow solver by continually updating and fixing critical issues and releasing monthly updates to the solver.
Legal notice

Multiband radiosity method with ray-traced view factors

Ray-traced view factors account for specular reflection and transmission when a model contains specular or transparent surfaces.

Unlike diffuse view factors, ray-traced view factors include the effects of specular reflections and transmissions but exclude diffuse reflections. As a result, when diffuse reflections are neglected, the ray-traced view factors correspond to gray-body view factors.

Ray tracing is performed independently across multiple spectral bands. Each traced ray carries a separate power value for every band. When a ray interacts with a surface, the power in each band is modified according to the material properties for that band. The ray continues if specular reflection or transmission occurs.

A surface can be transmissive in some bands and specularly reflective in others. In these cases, the original ray is split into two rays, and the power is distributed between them according to the material response.

For the single band radiosity method, the emissivity, diffuse reflectivity, and the area of an element are transformed into effective quantities that depend on the specular reflectivity ρ_s and transmissivity t. The transformations are:

Applying the same transformations to the multiband radiosity equations defines the following quantities.

ρ_s,kg—band-averaged specular reflectivity of element k in band g, defined as:

t_kg—band-averaged transmissivity of element k in band g, defined as:

A_kg^eff—band-effective Oppenheim area of element k in band g, defined as:

ε_kg^eff—band-effective emissivity of element k in band g, defined as:

F_k-j,g—view factor between element k and element j in energy band g. Because specularity and transmissivity can vary by band, the view factors can also vary by band.

For ray-traced view factors, the heat balance equation for the band Oppenheim element is:

The heat balance equation for the original radiating element is:

where:

The ray-traced non-gray radiosity equations follow the same form as the original single-band and multiband radiosity equations. The primary differences are that each band uses its own set of view factors and uses effective areas and emissivities instead of the actual areas and emissivities.