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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.
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.
General Workflow for Stress Analysis
The following steps outline the recommended workflow for stress analysis in Simcenter STAR-CCM+. These steps assume that you are already familiar with general Simcenter STAR-CCM+ tasks, such as creating parts, assigning parts to regions, or creating reports and scenes.
Generating a Mesh of 3D Finite Elements
This section outlines the steps for generating the volume mesh in Simcenter STAR-CCM+ using parts-based mesh operations. If you imported a CAE model volume mesh, and you wish to remesh it in Simcenter STAR-CCM+, you can use the same procedure.
Specifying the Orientation of Non-Conformal Interfaces
In multi-part assemblies, Simcenter STAR-CCM+ automatically handles non-conformal solid-solid interfaces based on a primary-secondary algorithm. In some applications, the presence of multiple interacting non-conformal interfaces may lead to over-constraining of the solid parts. In these cases, Simcenter STAR-CCM+ allows you to manually set the interface orientation to specify the primary and secondary boundaries.

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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.
- 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.
  - General Workflow for Stress Analysis
    The following steps outline the recommended workflow for stress analysis in Simcenter STAR-CCM+. These steps assume that you are already familiar with general Simcenter STAR-CCM+ tasks, such as creating parts, assigning parts to regions, or creating reports and scenes.
    - Preparing the Geometry
      Create or import the structure geometry in Simcenter STAR-CCM+ as a single part or a multi-part assembly.
    - Defining the Regions Layout
      Create the required regions, boundaries, and interfaces.
    - Selecting Solid Stress Physics Models
      Activate physics models for stress analysis and select the material laws that define the behavior of the solid.
    - Defining the Adaptive Time-Step
      When you model nonlinear phenomena, such as buckling or snap-through, the simulation time-step must be sufficiently small to capture the relevant physics. However, using a small time-step for the entire simulation can increase the computation time considerably.
    - Defining the Solid Materials
      Specify the materials for the solid structure and define their properties.
    - Generating a Mesh of 3D Finite Elements
      This section outlines the steps for generating the volume mesh in Simcenter STAR-CCM+ using parts-based mesh operations. If you imported a CAE model volume mesh, and you wish to remesh it in Simcenter STAR-CCM+, you can use the same procedure.
      - Specifying the Orientation of Non-Conformal Interfaces
        In multi-part assemblies, Simcenter STAR-CCM+ automatically handles non-conformal solid-solid interfaces based on a primary-secondary algorithm. In some applications, the presence of multiple interacting non-conformal interfaces may lead to over-constraining of the solid parts. In these cases, Simcenter STAR-CCM+ allows you to manually set the interface orientation to specify the primary and secondary boundaries.
    - Applying Constraints
      Applying a constraint on a surface, curve, or point, means prescribing one or more components of the displacement vector at that part entity. In stress analysis, you constrain the solid structure to mimic a real life scenario and to prevent the free displacement and rotation of the entire solid. Constraints are an effective way of reducing the number of modeled parts, and hence the simulation cost.
    - Applying Mechanical Loads
      The FE solid mechanics framework offers different types of mechanical loads: point loads, curve loads, surface loads, and body loads. You define point, curve, and surface loads on part entities using segments, whereas body loads are specified on the solid region.
    - Applying Thermal Loads
      When computing the solid displacement, the stress solver can account for the thermal expansion in response to changes in the solid temperature.
    - Prescribing Rigid Motion
      In transient simulations, you can model rigid motions of the solid structure by prescribing corresponding mesh motions. You can define rigid rotations, translations, or the trajectory of the structure in space. When computing the solid displacements, Simcenter STAR-CCM+ accounts for the elastic deformation due to the inertia forces that arise from acceleration of the solid structure.
    - Preparing Analysis Objects and Running the Simulation
      Prepare analysis object to monitor the solution during the simulation progress, then specify the solver settings and run the simulation.
    - Modeling Nonlinear Geometry
      By default, the Solid Stress model accounts for linear geometry phenomena. This section describes the additional steps that are required to model phenomena for which the strain-displacement relationship is nonlinear, such as applications involving large displacements or rotations of the solid structure.
  - Analyzing Normal Modes
    In solid mechanics, the normal modes of a solid structure describe the free vibrational motion of the structure at its natural (or resonant) frequencies. The free modes of vibrations of a structure govern its dynamic response to external forces and have an impact on its stress characteristics.
  - Fluid-Structure Interaction (FSI)
  - Deformable DFBI Bodies
    In Simcenter STAR-CCM+, the DFBI framework allows you to simulate the motion of a rigid body in response to external forces. In FSI simulations, you can use DFBI in conjuction with the solid stress solver to model deformable or partially deformable DFBI bodies. The DFBI module calculates the overall rigid body motion, while the solid stress solver computes the local deformations.
  - Solid Stress and Energy Reference
  - Mesh Requirements and Guidelines
    Finite element stress analyses in Simcenter STAR-CCM+ require a mesh of 3D solid elements generated using parts-based mesh operations, or imported as a CAE model. Simcenter STAR-CCM+ supports hexahedral, tetrahedral, wedge, and pyramid element types. Each type is available without mid-side nodes (linear element), or with mid-side nodes (quadratic element).
  - Solution Analysis Guidelines
    Simcenter STAR-CCM+ offers various field functions and tools that you can use to visualize the solution and monitor the relevant quantities. For example, you can visualize the deformed geometry and the stress and strain distribution throughout the solid structure.
  - Bibliography
- 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.

Specifying the Orientation of Non-Conformal Interfaces

In multi-part assemblies, Simcenter STAR-CCM+ automatically handles non-conformal solid-solid interfaces based on a primary-secondary algorithm. In some applications, the presence of multiple interacting non-conformal interfaces may lead to over-constraining of the solid parts. In these cases, Simcenter STAR-CCM+ allows you to manually set the interface orientation to specify the primary and secondary boundaries.

In the primary-secondary algorithm for non-conformal mesh, the secondary side of the interface corresponds to the boundary which is more flexible, that is, the boundary with a finer mesh. Simcenter STAR-CCM+ automatically specifies the secondary boundary based on the average dimension of the mesh element faces at each side of the interface. If the automatic specification results in over-constraining of the parts, Simcenter STAR-CCM+ issues a warning message similar to the following:

NOTE: multiple constraints from groups of interacting solid solid interfaces:{17,18}
NOTE: if the result is incorrect or the matrix singular, it might be due to over/redundant constraint from interacting solid solid interfaces.  
You may use Manual Orientation to select the secondaries manually. In Manual Orientation, each secondary vertex is constrained only once.

When Simcenter STAR-CCM+ issues this warning, specify the orientation of interacting interfaces manually. For all other interfaces, leave the automatic orientation.

For interfaces that interact which other:

Select the relevant Interfaces > [Interface] > Orientation node and set Mode to Manual.
The Orientation node is only available for interfaces between parts that are assigned to the same region.

When using manual orientation, Simcenter STAR-CCM+ specifies the interface boundary Part 1/Part 2 [0] as the secondary boundary. You can change the orientation of the contacts to specify the other side of the interface as boundary [0]:

Right-click the Orientation node and select Reverse Contacts...
You can check the interface orientation by examining the icon next to the associated contact.