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Turbomachinery getting started
This getting started guide provides a comprehensive introduction to thermal modeling for turbomachinery applications using Simcenter 3D Thermal Multiphysics.
Introducing boundary conditions
This topic explains the different types of boundary conditions used in turbomachinery simulations and how thermal, shared, and structural conditions are applied through simulation objects, constraints, and loads to represent multiphysics behavior.
Thermal coupling
This topic explains how to model heat transfer between components that are not directly connected through the mesh in WEM simulations.
Guidelines for modeling perfect contact behavior using Thermal Coupling
This topic describes a recommended approach for defining thermal coupling coefficients based on material properties and mesh size.

Knowledge base articles
Knowledge base articles provide concise, practical guidance for solving thermal, flow, multiphysics, space systems, and turbomachinery modeling challenges in Simcenter 3D.
Space thermal getting started
This getting started guide provides a comprehensive introduction to space thermal modeling using Simcenter 3D Space Systems Thermal (SST).
Turbomachinery getting started
This getting started guide provides a comprehensive introduction to thermal modeling for turbomachinery applications using Simcenter 3D Thermal Multiphysics.
- Getting started with turbomachinery in Simcenter 3D
- Fundamentals of turbomachinery systems
  This topic introduces turbomachinery and explains how gas turbines convert working-fluid energy into mechanical energy or thrust. You will learn how turbomachines are classified, how the Brayton cycle describes gas turbine operation, and how the main gas turbine sections, components, and cooling systems support safe and efficient performance.
- Gas turbine design disciplines and data exchange
  This topic introduces the main engineering disciplines involved in gas turbine design and explains how they exchange data throughout the development process. You will learn how different teams collaborate, what data they produce, and how iterative workflows drive the final engine design.
- Introducing Whole Engine Model (WEM)
  This topic introduces the WEM and explains its role in gas turbine design. You will learn how WEM captures the thermal and structural behavior of the engine, what inputs it requires, and how it supports clearance and mechanical integrity assessments.
- Introducing the user interface
  This topic covers the user interface (UI) in Simcenter 3D Thermal Multiphysics. You will learn how to navigate the modeling environment and how to efficiently use the available tools, menus, and commands to build, set up, and review your models.
- Preparing geometry for WEM
  This topic explains why geometry preparation is critical for WEM analysis. You will learn how to simplify 3D CAD geometry into efficient 2D or hybrid models and how to prepare geometry for meshing and simulation in Simcenter 3D.
- Meshing strategy
  This topic explains how to create finite element models for WEM by combining multiple mesh types and abstraction levels.
- Managing parts and assemblies
  This topic explains how to manage parts and assemblies in WEM using associative geometry, collaborative simulation capability, and integration of submodels into a full engine simulation.
- Condition sequences
  This topic explains how condition sequences define and manage engine operating conditions over a mission cycle in WEM.
- Introducing boundary conditions
  This topic explains the different types of boundary conditions used in turbomachinery simulations and how thermal, shared, and structural conditions are applied through simulation objects, constraints, and loads to represent multiphysics behavior.
  - Thermal coupling
    This topic explains how to model heat transfer between components that are not directly connected through the mesh in WEM simulations.
    - Thermal coupling methods
      This topic explains coupling methods that the thermal solver supports. You will learn element subdivision and projective intersection coupling methods, how to calculate overlapped area, understanding overlap projection direction, how to control coupling resolution, and visualize thermal coupling connections.
    - Thermal coupling types
      This topic explains the different types of thermal coupling and provides guidance on where each type should be used. The type of thermal coupling you define is determined by the geometry of the source and target regions you specify, as well as the type of heat transfer such as conduction, convection, and radiation.
    - Thermal coupling in models containing internal lines
      This topic explains how to model thermal coupling in axisymmetric models with internal lines.
    - Modeling considerations for embedded edges
      This topic explains how to model thermal contacts with embedded edges.
    - Guidelines for modeling perfect contact behavior using Thermal Coupling
      This topic describes a recommended approach for defining thermal coupling coefficients based on material properties and mesh size.
    - Connecting bolts and nuts in the axisymmetric models
      This topic explains how to accurately model thermal contacts with bolts and nuts in turbomachinery models.
  - Convection boundary conditions
    This topic explains what thermal boundary conditions you can use for convection.
  - Fields, expressions and plugins
    This topic explains how to define boundary condition inputs in Simcenter 3D using fields, expressions, and plugin functions. These tools allow you to model complex, time- and space-dependent behavior efficiently.
  - Radiation modeling
    This lesson explains the two Radiation simulation object types and how each defines radiative enclosures and affects radiation calculation efficiency.
  - Cyclic Symmetry
    This topic explains how to use Cyclic Symmetry in turbomachinery thermal models.
- Solving a model
  This topic explains how to configure thermal-solver settings in WEM, including convergence criteria, discretization methods, integration methods, and axisymmetric-segment control for accurate and efficient thermal analyses.
- Post-processing results
  This lesson introduces post-processing commands to help you review and evaluate simulation outcomes using visualization and data analysis.
- Mechanical integrity
  This topic explains how thermal results from WEM are mapped to detailed component models for structural and mechanical integrity analyses.
- Blade cooling
  This topic explains why blade cooling is critical in gas turbines and how advanced cooling technologies allow turbine components to operate at temperatures above material limits.
- Troubleshooting the model
  This topic explains how to verify FEM quality, material definitions, mesh integrity, and element properties before solving a thermal model.

Guidelines for modeling perfect contact behavior using Thermal Coupling

This topic describes a recommended approach for defining thermal coupling coefficients based on material properties and mesh size.

Introduction

When creating thermal models, you often need thermal coupling interfaces to transfer heat between non-conformal meshes or between different modeling representations. Choosing an appropriate thermal coupling coefficient is critical for obtaining physically realistic results.

Physics-based HTC estimation

Avoid selecting an arbitrary thermal coupling coefficient, such as 1000 W/(m²·K). The purpose of a thermal coupling heat transfer coefficient (HTC) is not to model convection, but to reproduce the conductive heat transfer across a near-perfect contact interface. An HTC that is too low introduces artificial thermal resistance, while an HTC that is too high can lead to excessive numerical diffusion. A more physically consistent approach is to estimate the HTC from the material thermal conductivity and the local mesh size.

For a conductive interface, the heat flux can be approximated using Fourier's law:

Where:

k is the material thermal conductivity.
T_primary is the temperature on the primary side.
T_secondary is the temperature on the secondary side.
L is the distance between the centroids of the elements adjacent to the interface. For a uniform mesh, L is approximately equal to the element size.

Equating this conductive heat transfer to the thermal coupling formulation leads to the following estimate for the thermal coupling coefficient:

Where:

h is the thermal coupling coefficient.
k is the material thermal conductivity.
L is the characteristic element size normal to the interface.

This formulation provides a physically meaningful HTC that scales automatically with both material properties and mesh density.

Interfaces between different materials

When the two sides of the thermal coupling have different materials or different mesh sizes, use the following generalized expression:

Where:

k₁ and k₂ are the thermal conductivity of the primary and secondary side, respectively.
Δx₁ and Δx₂ are the element height normal to the interface on the primary and secondary side, respectively.