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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.
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.
Morphing
The morpher motion allows you to account for the effect of moving boundaries on your analysis in a transient simulation.
Morphing Workflow
You can model morphing in Simcenter STAR-CCM+ using either RBF or BSpline interpolation. Set the properties for the selected morpher and the conditions at the boundaries. The workflow may include additional motions, depending on the set up of the physics continua and models chosen.
Applying Rigid Prism Layer Morphing
In a flow simulation, the prism layer thickness has an impact on the accuracy of the y+ calculation on a wall boundary. To avoid deforming the prism layer during morphing unnecessarily, you can apply the Rigid Prism Layer Morphing method. A threshold distance defines when the prism layer calls can be morphed in the case of a decreasing gap between this boundary and another.

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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.
  - Overset Meshes
    Overset meshes are used to discretize a computational domain with several different meshes that overlap each other in an arbitrary manner. They are most useful in problems dealing with large motions as well as optimization studies where a geometry can be enclosed in an overset region and set to different positions.
  - Morphing
    The morpher motion allows you to account for the effect of moving boundaries on your analysis in a transient simulation.
    - Morphing Workflow
      You can model morphing in Simcenter STAR-CCM+ using either RBF or BSpline interpolation. Set the properties for the selected morpher and the conditions at the boundaries. The workflow may include additional motions, depending on the set up of the physics continua and models chosen.
      - Preparing for a Morpher Analysis
        The computational resource that is required to run the morpher is directly related to the number of control points present in the regions for which the morpher is active.
      - Setting up Morpher Motion and Solver
        You can model mesh morphing in Simcenter STAR-CCM+ using either RBF or BSpline interpolation methods for defining the deforming surfaces.
      - Setting Morpher Boundary Properties
        Specify the morpher properties on the boundaries of your simulation.
      - Including Additional Control Points
        In many simulations the control points that contribute to the morpher interpolation field come from boundary vertices. However, you can also specify additional control points—and their associated displacements—by defining point sets within the Point Sets node.
      - Applying Rigid Prism Layer Morphing
        In a flow simulation, the prism layer thickness has an impact on the accuracy of the y+ calculation on a wall boundary. To avoid deforming the prism layer during morphing unnecessarily, you can apply the Rigid Prism Layer Morphing method. A threshold distance defines when the prism layer calls can be morphed in the case of a decreasing gap between this boundary and another.
      - Visualizing the Morpher Displacement
        Use the Morpher Displacement field function to analyze how the morpher affects the volume mesh and to compare the output with expected results.
    - Point Set Reference
      You define the different types of point sets through the point set dialogs.
    - Morpher Motion Reference
      You control the morpher mesh movement through various settings and properties that Simcenter STAR-CCM+ applies at boundaries, regions, and interfaces.
    - Working with Interfaces and Morphing
      It is important to apply the correct conditions at interfaces between the regions as failing to do so could result in the mesh being badly distorted. Two different scenarios can exist: internal interfaces and sliding interfaces.
    - Understanding the Interaction of Control Planes and Control Points
      Control planes (in the Fixed Boundary Plane and Boundary Plane morpher constraint specification methods) work by damping out the displacements smoothly to zero over a specified zone of influence. The RBF morpher requires damping to be applied at these boundaries—for the Fixed Boundary Plane type, the damping applies to displacements in all directions; for the Boundary Plane type, the damping only applies to normal displacements. The BSpline morpher does not require any damping function to be applied.
    - Troubleshooting Negative Volume Cells
      Poor quality or negative volume cells may occur when setting up a morpher analysis. These can be identified by examining the grid at various stages using visualisation tools: such as reports, plots and scalar field functions.
    - Mesh Morpher Solver Reference
      The Mesh Morpher solver is designed to control the morphing motion calculations with specialized properties. It becomes available when a region has the morphing motion selected.
    - Morpher Boundary Condition Reference
    - Morphing Field Functions
      The following primitive field function is made available to the simulation when the morpher motion model is used. This field function has a typical set of base properties.
    - Motion Bibliography
  - Adaptive Mesh Refinement
    Adaptive Mesh Refinement (AMR) is a dynamic method that refines or coarsens cells based on adaptive mesh criteria as they query the flow solution. Solution quantities are automatically interpolated to the adapted mesh.
  - General Remeshing
    Simcenter STAR-CCM+ provides a remeshing model within a physics continuum that triggers remeshing when certain conditions are met. Built-in conditions are provided based on mesh quality checks, and you can also configure your own trigger on the remeshing solver.
- 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.
- 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.

Applying Rigid Prism Layer Morphing

In a flow simulation, the prism layer thickness has an impact on the accuracy of the y+ calculation on a wall boundary. To avoid deforming the prism layer during morphing unnecessarily, you can apply the Rigid Prism Layer Morphing method. A threshold distance defines when the prism layer calls can be morphed in the case of a decreasing gap between this boundary and another.

A boundary is considered as a rigid boundary when its Morpher Specification is set to Fixed or Displacement.

For a rigid boundary, you can activate the Rigid Prism Layer Morphing option, which prevents the cells in the prism layer from being deformed. If the option is activated, you specify the Minimum Gap to Another Boundary, which is a threshold that determines whether the morpher preserves the prism layer cells or not. When the distance between the wall boundary and any other boundary approaching is above the Minimum Gap to Another Boundary value, the prism layers are not deformed. When the distance shrinks below the threshold value, the prism layer cells are morphed in order to maintain mesh quality.

After the morpher solver identifies the prism layers, a field function named Prism Layer Level is added to the regions in which the morpher is activated. If you are assessing the effectiveness of the Rigid Prism Layer Morphing, visualize this field function for the relevant regions. For more details, refer to Prism Layer Level.

To activate Rigid Prism Layer Morphing:

Set the boundary's Morpher Specification to Fixed or Displacement.
Select the Physics Values > Rigid Prism Layer Morphing node and activate Rigid Prism Layer Morphing.

Set the value for Minimum Gap To Another Boundary to a distance below which the prism layer cells are deformed.

Note	If this value is set to 0.0, (the default value), then the prism layer cells are not deformed. However, negative volume cells can result if the distance to another boundary becomes too small.