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Thermal Solver
Contains thermal solver related guides, such as the TMG reference manual, thermal API guide, and error message list.
Thermal solver theory
Describes the theory and methods of the thermal solver.
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.
Head loss coefficients in curved ducts
Understanding the pressure loss in bends using head loss coefficients for both laminar and turbulent flow conditions.

Thermal Solver
Contains thermal solver related guides, such as the TMG reference manual, thermal API 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 methods
    Thermal radiation is a heat transfer due to electromagnetic radiation emitted by the surface of bodies due to their temperature.
  - 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.
    - Hydraulic flow resistances for incompressible flows
      Hydraulic resistances are modeled with 2-node hydraulic elements.
    - Straight ducts
      For straight ducts, the flow is assumed to be fully developed, and the flow resistance factor (RF) is calculated using a specific formula based on duct characteristics.
    - Nozzles and diffusers
      The thermal solver computes the flow resistance factor for nozzles and diffusers based on the angles α and β, and various coefficients.
    - Duct geometry consideration for rough and curved ducts
      For fully developed flow through straight, smooth ducts, the thermal solver supports a wide range of friction factor and heat transfer correlations for different duct geometries.
    - Rough duct correlations
      Rough duct correlations use different friction factors for laminar, turbulent, and transitional flow. Nusselt numbers used in the correlations for rough ducts also change depending to flow conditions.
    - Head loss coefficients in curved ducts
      Understanding the pressure loss in bends using head loss coefficients for both laminar and turbulent flow conditions.
    - Heat transfer correlations in curved ducts
      Understanding heat transfer coefficients in curved ducts and the proposed correlation for different bend angles.
    - Head loss in sharp duct bends and duct branches
      The thermal solver uses the head loss in sharp duct bends and duct branches.
    - One-way conductance
      Modeling the heat transported by the fluid through one-way conductance for each flow resistance.
  - Miscellaneous topics
  - Thermal solver theory bibliography
    The following bibliography lists all sources used to explain how the thermal solver works.
- Thermal solver API
  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.

Head loss coefficients in curved ducts

Understanding the pressure loss in bends using head loss coefficients for both laminar and turbulent flow conditions.

The pressure loss in a bend can be calculated with the total loss coefficient K as:

where K is given by:

Correlations for bends are generally given for K, f_curved, or K*. Here, we transform all correlations into expressions of the form f_curved/f_straight using the relations:

and

Laminar flow Re < 2300

The Dean number is defined as:

where a = D_h/2. The following correlations are given by Idelchik [12] for laminar flow:

Turbulent flow Re > 2300

Ito gives correlations for bends of discrete angles of 45, 90, and 180 degrees, while Idelchik provides more general correlations. The Ito correlations are used preferentially over Idelchik’s within their range of validity:

For

For

where

These correlations are valid over the range 2x104 < Re < 4x105 and 2 < R/a <15. They are used with angles φ plus or minus 1 degree of the given discrete values (i.e., 44 to 46 degrees, 89 to 91 degrees, and 179 to 181 degrees).

Outside of this range of validity, the Idelchik correlation is used:

where for