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Physics Simulation
Simcenter STAR-CCM+ can model a wide range of physics phenomena including fluid mechanics, solid mechanics, heat transfer, electromagnetism, and chemical reactions. Scenarios with multiple time scales can be solved within the same simulation.
Reacting Flow
Simcenter STAR-CCM+ provides a selection of models that you can use to simulate a wide range of reacting flow applications.
Reacting Species Transport
When using Reacting Species Transport models, Simcenter STAR-CCM+ solves transport equations for the mass fractions of all species that are involved in the chemical reactions. These species mass fractions are passed to a separate chemistry solver that returns the amount of product.
Reacting Species Transport Reference
This section provides reference material, including properties, sub-nodes, field functions, and other model-specific settings, for all of the reacting species transport models.
Acceleration Factor Control Properties
You can specify a fixed acceleration factor, or allow Simcenter STAR-CCM+ to set it automatically.

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Physics Simulation
Simcenter STAR-CCM+ can model a wide range of physics phenomena including fluid mechanics, solid mechanics, heat transfer, electromagnetism, and chemical reactions. Scenarios with multiple time scales can be solved within the same simulation.
- Defining Physics Workflow
  Simcenter STAR-CCM+ contains a wide range of physics models and methods for the simulation of single- and multi-phase fluid flow, heat transfer, turbulence, solid stress, dynamic fluid body interaction, aeroacoustics, and related phenomena. These physics models are all selected using a physics continuum.
- Setting Up Physics
  This section provides information on how to set up physics models in STAR-CCM+.
- Running Physics Simulations
  This part of the documentation describes preparation and procedures for running a Simcenter STAR-CCM+ simulation.
- Motion
  In general, motion can be defined as the change in position of a body with respect to a certain reference frame.
- Space
  The primary function of the Space models in Simcenter STAR-CCM+ is to provide methods for computing and accessing mesh metrics. Examples of mesh metrics include cell volume and centroid, face area and centroid, cell and face indexes, and skewness angle.
- Time
  The primary function of the time models in Simcenter STAR-CCM+ is to provide solvers that control the iteration and/or unsteady time-stepping.
- Mesh Motion and Adaption
  Many simulations that involve motion or geometry change require you to move or deform the mesh. Other simulations require localized mesh adaption in order to achieve an accurate solution.
- Materials
  Material models simulate substances, including various mixtures.
- Fluid Flow
  Many engineering design projects require you to predict the effect of flowing fluids on containing structures or immersed objects. While you can analyse simple scenarios with hand calculations, complex scenarios require you to apply numerical methods for accurate solutions.
- Viscous Flow
  Viscous Flow is a finite element approach for use with viscoelastic materials and other highly viscous non-Newtonian fluids, such as liquid plastics and rubber, dough and similar foodstuffs, molten glass, and mud. Viscoelastic materials resemble elastic materials, but also exhibit viscous effects, rebounding slowly from deformations.
- Passive Scalars
  Passive scalars are user-defined variables of arbitrary value, assigned to fluid phases or individual particles. They are passive because they do not affect the physical properties of the simulation. An intuitive way to think of passive scalars is as tracer dye in a fluid, but with numerical values instead of colors, and with no appreciable mass or volume.
- Heat Transfer
  Heat transfer is the study of energy in transit due to a temperature difference in a medium or between media. Heat transfer extends thermodynamic analysis through the study of the modes of energy transfer and through development of relations to calculate energy transfer rates.
- Species
  This chapter provides information about the chemical species models in Simcenter STAR-CCM+. A species model is activated whenever a multi-component liquid or multi-component gas is chosen from the Material model section of the Physics Model Selection dialog.
- Porous Media
  Simcenter STAR-CCM+ allows you to simulate the transport of a fluid or energy (e.g. heat, electrical charge) through porous materials using the concept that the action of the porous media can be represented using appropriate loss (or 'diffusion') coefficients.
- Adjoint
  The adjoint method is an efficient means to predict the influence of many design parameters and physical inputs on some engineering quantity of interest, that is, on the engineering objective of the simulation. In other words, it provides the sensitivity of the objective (output) with respect to the design variables (input).
- Fans and Blowers
  Simcenter STAR-CCM+ provides models for axial and radial fans where classical fan laws apply.
- Virtual Disk Model
  The virtual disk model is based upon the principle of representing propellers, turbines, rotors, fans, and so on, as an actuator disk. The actuator disk treatment is practical when you are concerned about the influence of the rotor/propeller behavior on the flow rather than knowing about the detailed interactions between the flow and the blades of the rotating device.
- Turbulence
  Most fluid flows of engineering interest are characterized by irregularly fluctuating flow quantities.
- Transition
  The term transition refers to the phenomenon of laminar to turbulence transition in boundary layers. A transition model in combination with a turbulence model predicts the onset of transition in a turbulent boundary layer.
- Wall Distance
  Wall distance is a parameter that represents the distance from a cell centroid to the nearest wall face with a non-slip boundary condition. Various physical models require this parameter to account for near-wall effects.
- Radiation
  The Radiation Model is the gateway, or entry point to all of the radiation modeling capabilities of Simcenter STAR-CCM+. This section describes Simcenter STAR-CCM+’s radiation modeling.
- Aeroacoustics
  Aeroacoustics investigates the aerodynamic generation of sound.
- Reacting Flow
  Simcenter STAR-CCM+ provides a selection of models that you can use to simulate a wide range of reacting flow applications.
  - Reacting Flow Applications
    It is possible to model many different types of reacting flow applications using combinations of the reacting flow models that are provided in Simcenter STAR-CCM+.
  - Reacting Flow General Workflow
    Simcenter STAR-CCM+ supports several types of combustion analysis, each with their own workflow. Use this section to help identify the choice of models that are appropriate for the type of analyses you intend.
  - Reacting Flow General Reference
    Some reference material is common to different sub-sections within the reacting flow material.
  - Reacting Species Transport
    When using Reacting Species Transport models, Simcenter STAR-CCM+ solves transport equations for the mass fractions of all species that are involved in the chemical reactions. These species mass fractions are passed to a separate chemistry solver that returns the amount of product.
    - Chemistry Acceleration
      You can use Clustering, ISAT, or Dynamic Mechanism Reduction methods to speed up Complex Chemistry calculations.
    - Reacting Species Transport Workflow
      Use this workflow for simulating multi-component liquid reactions or gas-phase turbulent flames which involve kinetic phenomena such as flame ignition, slowly forming pollutants, flame quenching, and extinction.
    - Polymerization Workflow
      Polymerization processes involve various chemical reactions during which monomer molecules combine to form polymer chains. These processes require the reacting species transport physics model in Simcenter STAR-CCM+.
    - Reacting Species Transport Reference
      This section provides reference material, including properties, sub-nodes, field functions, and other model-specific settings, for all of the reacting species transport models.
      - Complex Chemistry Model Reference
        The Complex Chemistry model requires gas-phase or liquid-phase chemical mechanisms which typically contain tens or hundreds of species, with hundreds or thousands of reactions. Since different species evolve at different rates, the kinetics are termed stiff, and integrating the reaction step is computationally expensive.
      - Approximation Options Properties
        The Approximations Options node is available when using the Complex Chemistry model.
      - Chemistry Acceleration Properties
        The Complex Chemistry > Chemistry Acceleration node allows you to speed up complex chemistry calculations using In-Situ Adaptive Tabulation (ISAT), Clustering, or Dynamic Mechanism Reduction.
      - CVODE Properties
        The Complex Chemistry model uses the CVODE ODE solver.
      - Acceleration Factor Control Properties
        You can specify a fixed acceleration factor, or allow Simcenter STAR-CCM+ to set it automatically.
      - Turbulence-Chemistry Interactions Model Reference
        Turbulence-chemistry interactions require additional modeling, as well as RANS or LES modeling, to allow chemical reactions in thin reaction zones to be solved.
      - Turbulent Flame Speed Closure (Complex Chemistry) Model Reference
        The Turbulent Flame Speed Closure (Complex Chemistry) model is a turbulence-chemistry interactions model which you can use with the Complex Chemistry model.
      - Eddy Break-Up Model Reference
        Eddy Break-Up (EBU) combustion models solve individual transport equations for mean species concentrations on the computational grid.
      - Restoring the Premixed Eddy Break Up Model
        The Premixed Eddy Break-Up model in Simcenter STAR-CCM+ v.11.04 behaves as a Partially Premixed version. You can restore the Premixed model settings as described in this section.
      - Eddy Contact Micromixing Model Reference
        This physics model allows you to model turbulent molecular-scale mixing and reaction of multi-component liquids, dominated by viscous-convective and viscous-diffusive processes.
      - Thickened Flame Model Reference
        The propagation speed of premixed flame fronts depends on the rate that heat and species diffuse into the flame as well as the subsequent chemical reaction rate. To capture the correct propagation speed with a specified diffusion model and a chemical reaction model, the internal flame structure must be resolved.
      - Polymerizaton Model Reference
        Polymerization is the process of creating long-chain molecules by chemically combining large numbers of small monomer molecules. This process starts by mixing monomer and initiator molecules in a solvent.
  - Flamelet
    Flamelet models avoid the computational expense of complex chemistry calculations by pre-calculating the chemistry in gas-phase laminar flames using simple 0D or 1D geometries with detailed chemical mechanisms. A reduced set of variables are used to parameterize and tabulate the species from these simple flames, which are then interpolated in the 3D simulation of turbulent flames in Simcenter STAR-CCM+.
  - Emissions
    Emissions are unwanted pollutant species that are by-products of reactions. There are two options to model pollutant species in Simcenter STAR-CCM+. When using the Complex Chemistry model, you can include the pollutant species in the chemical mechanism. For all other models, in particular Flamelet models and the Eddy Break-Up (EBU) model, separate transport equations for the pollutant species are solved.
  - Interphase
    There are many applications that involve the transport of reacting particles, such as calcination and char oxidation. You can simulate the process of interphase reactions using Lagrangian Multiphase, Multiphase or Fluid Film models.
  - Intraphase
    You can simulate reactions that occur within one Eulerian phase using Flamelet or Reacting Species Transport combustion models in that phase.
  - Surface Chemistry
    The Surface Chemistry model is used to represent surface reaction mechanisms on interfaces, boundaries, or surfaces in porous regions. You can use this model to simulate applications such as monolithic catalysts, chemical vapor deposition (CVD), and packed bed reactors.
  - Reacting Channels
    The Reacting Channel Coupling feature provides the ability to exchange data between a three-dimensional Simcenter STAR-CCM+ simulation and a one-dimensional Plug Flow Reactor (PFR) simulation which uses the CVODE solver. You can use the Reacting Channel co-simulation model in Simcenter STAR-CCM+ to solve reacting flow simulations in tubular heat exchangers with channels that are long and thin.
  - Reactor Network
    You can reduce the computational cost of solving complex chemistry for each cell in the computational domain of a steady combustor by simulating with an economical combustion model—such as a flamelet model, or the Eddy Break-Up (EBU) model—then clustering cells into a specified number of reactors and solving detailed chemistry on this network of reactors.
  - Common Reacting Flow Actions
    This section contains short sets of instructions that describe how to perform some of the actions which are common to several of the reacting flow detailed workflows.
- Internal Combustion Engines
  In an internal combustion engine (ICE), for example a gasoline engine, the process of combustion takes place in a cylinder (or cylinders) within the engine. The working fluid is a fuel and oxidizer mixture (usually air), which reacts to form combustion products.
- Multiphase Flow
  Multiphase flow is a term which refers to the flow and interaction of several phases within the same system where distinct interfaces exist between the phases. Simcenter STAR-CCM+ considers flow options where phases coexist as: gas bubbles in liquid, liquid droplets in gas, and/or solid particles in gas or liquid, and/or (large scale) free surface flows.
- Dynamic Fluid Body Interaction
  Dynamic Fluid Body Interaction (DFBI) in Simcenter STAR-CCM+ allows you to simulate the motion of a 6-DOF body with the displacement and rotation resulting from the defined mechanical and multiphysics interaction (flow, DEM, solid stress, EMAG).
- Harmonic Balance
  Some unsteady flows have a regularly repeating flow pattern, that is, they are time-periodic. Consider the flow from a fan blade passing across the entrance to a duct. Measurements of the instantaneous flow just within the duct would show a regularly repeating pattern. If the flow disturbances are sufficiently large, and propagate to the end of the duct, measurements of the unsteady flow at any point within the duct show repeating patterns. Such time-periodic patterns can be expressed using Fourier series.
- Solid Stress
  Simcenter STAR-CCM+ allows you to model the response of a solid continuum to applied loads, including mechanical loads and thermal loads that result from changes in the solid temperature.
- Electromagnetism
  Simcenter STAR-CCM+ allows you to model engineering applications involving electromagnetic phenomena. Example applications are electric motors, electric switches, and transformers, which can be modeled based on the classical theory of Electromagnetism.
- Electrochemistry
  Electrochemistry is the study of chemical reactions which occur due to an imposed electrical charge, or a difference in electrical potential at a boundary between a conductor–such as a metal–and an electrolyte. Simcenter STAR-CCM+ provides models that allow you to simulate batteries, corrosion, etching, and other electrochemical reactions.
- Electric Circuits
  Electrical circuits are conducting loops of interconnected electrical components, such as batteries, power sources, resistors, and inductors.
- Plasma
  Plasma is a state of matter similar to a gas that is composed partially or completely of charged particles such as ions and electrons which are not bound to each other.
- Batteries
  You can simulate batteries in Simcenter STAR-CCM+ using battery cells and battery cycling procedures that are defined either directly in Simcenter STAR-CCM+, or in the external software package Simcenter Battery Design Studio.
- Casting
  Casting simulations are performed using transient multiphase simulations using the VOF model with solidification. Conjugate heat transfer is applied between the solidifying melt and the solid mold.
- Region Sources
  This section provides some guidelines on how to use region sources for some common problems.
- Cell Quality Remediation
  The Cell Quality Remediation model helps you get solutions on a poor-quality mesh. This model identifies poor-quality cells, using a set of predefined criteria, such as Skewness Angle exceeding a certain threshold. Once these cells and their neighbors have been marked, the computed gradients in these cells are modified in such a way as to improve the robustness of the solution.
- Guidelines for Applying Simcenter STAR-CCM+
  This part of the documentation provides guidelines on applying Simcenter STAR-CCM+ models to your applications.
- Common Solvers Reference
  In Simcenter STAR-CCM+, solvers compute the solution during the simulation run.

Acceleration Factor Control Properties

You can specify a fixed acceleration factor, or allow Simcenter STAR-CCM+ to set it automatically.

The acceleration factor specifies the level of linearization that is applied to the stiff complex chemistry reaction source terms

ω_{i}

for the

i

'th species in Eqn. (3412). When the acceleration factor is low, a high level of source term linearization occurs and the solution converges slowly. Increasing the acceleration factor decreases the linearization and speeds up the solution. However, when the acceleration factor is too high, the solution can diverge.

The Acceleration Factor Control node only appears under the Complex Chemistry model when using the Steady model.

Automatic Control: When activated, Simcenter STAR-CCM+ dynamically adjusts the acceleration factor that is used as the solution proceeds. When deactivated, you specify a fixed Acceleration Factor.; Simcenter STAR-CCM+ monitors the behaviour of a small proportion of the most recent reacting species residuals as it adjusts the acceleration factor. At any given time, whichever reacting species residuals have the largest values are monitored—these may change during iterations. As the solution proceeds, Simcenter STAR-CCM+ compares a Residual Sample Size of consecutive residual values from each of the selected residuals to their respective least squares approximation to see what proportion of values fit the line. Based on these comparisons, Simcenter STAR-CCM+ increases, decreases, or maintains the acceleration factor—starting from a specified Initial Acceleration Factor.
Acceleration Factor: Available when Automatic Control is deactivated.; Set a value between 0.0 (full $ω_{i}$ source term linearization—which is slow to run) and 1.0 (no $ω_{i}$ source term linearization—which is faster to run, but less stable). A value of 0.5 is appropriate for the majority of simulations—however, if residuals diverge, lower this value.