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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.
Fans and Blowers
Simcenter STAR-CCM+ provides models for axial and radial fans where classical fan laws apply.
Modeling the Fan Swirl
You can model the fan swirl in your simulation.

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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.
  - Overview of Fan Performance Curves
    A fan performance curve describes the performance of a fan under specific operating conditions.
  - Fan Pressure Components
    This section defines the fan pressure components that are used in deriving fan performance curves.
  - Fan Configurations
    The three essential fan configurations are ducted fan, forcing fan, and exhausting fan.
  - Modeling Fan Performance Curves
    The fan performance curves that are supplied by fan manufacturers plot the pressure rise across that fan against the flow rate.
  - Using the Fan Interface
    This section describes how to implement a fan interface in your simulation.
  - Creating a Fan Interface
    Each interface has a direction from side 0 to side 1. When you create the interface, select side 0 first and then select side 1. For a fan interface, side 0 is upstream to side 1.
  - Fan Interface Properties
    The Fan Interface node has properties, conditions, values, and a pop-up menu.
  - Specifying the Fan Performance Curve Type
    The fan performance curve specifies the pressure rise across the fan interface.
  - Specifying the Fan Performance Curve as a Table
    When you set up a fan interface, you can specify the fan performance curve as a table.
  - Specifying the Fan Performance Curve as a Polynomial Function
    When you set up a fan interface, you can specify the fan performance curve as a polynomial function.
  - Specifying the Fan Performance Curve Polynomial
    The fan performance curve can be specified as a polynomial function.
  - Specifying the Fan Curve Temperature Scaling
    You can modify the fan performance curve in response to temperature.
  - Modeling the Fan Swirl
    You can model the fan swirl in your simulation.
  - Orientation of Contact-Mode Boundary Interfaces
    The Orientation node is only available for interfaces between parts that are assigned to the same region. These interfaces are therefore contact-mode boundary interfaces within the same region, where Simcenter STAR-CCM+ requires an additional specification for orientation. This specification is particularly required for interface types such as fan, blower, and fully-developed.
  - Setting the Fan Interface Verbosity
    When fan verbosity is activated, a report is printed to the Output window for every iteration. The report includes the calculated operating point of the fan: the pressure rise and flow rate value pair that lies on the fan curve at that iteration.
  - Adjusting the Fan Interface Intersection Tolerance
    The intersection tolerance applies to all direct interfaces. The tolerance is the fraction of the length of the smallest edge that is attached to the vertex.
  - Creating a Blower Interface
    The blower interface in Simcenter STAR-CCM+ allows you to model two types of radial fans: centrifugal fans and impeller fans.
  - Blower Interface Properties
    This section describes the properties and physics values that you can specify for a blower interface.
  - Modeling the Blower Swirl
    You can model the blower swirl in your simulation.
  - Modeling Multiple Fans and Blowers in a Single Interface
    With per-contact values you can model any number of fans or blowers, with different fan curves, in a single parts-based interface.
  - Using the Fan Momentum Source
    The fan momentum source applies the effect of a rotating fan to the fluid cells within a region that you select. Using a fan momentum source implies that you already have a separate region that is located at the position of the fan.
  - Importing the Fan Performance Data Table
    Simcenter STAR-CCM+ calibrates the fan momentum source in your simulation with performance data from a real fan.
  - Activating the Fan Momentum Source
    You activate the fan momentum source in the appropriate fluid region.
  - Specifying the Fan Performance Curve
    After you have imported the fan performance curve table, set the appropriate Fan Momentum Source properties.
  - Fan Momentum Source Properties
    You specify the upstream and downstream boundaries of the fan momentum source, and set the operating rotation rate and the blade angle of the fan.
  - Scaling the Fan Performance Curve
    A fan performance curve is for a specific fan rotation rate and fluid temperature. If your simulation uses a different fan rotation rate or a different fluid temperature from the fan performance curve that you specified in your simulation, the fan performance curve must be modified to suit those conditions.
  - Working with the Fan Solver
    The Fan Solver node contains properties that control how the fan momentum source is solved. You can specify the fan solver property values to suit your simulation.
- 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.

Modeling the Fan Swirl

You can model the fan swirl in your simulation.

You can use either the Calculated option, based on Eqn. (5031), or the User-Specified option to calculate the swirl downstream of the fan. By default, fan swirl is not included.

For more information, refer to the Fan Interface formulation.

To include the fan swirl in your simulation:

Expand the Interfaces > [Interface Name] > Physics Conditions node, and click Fan Swirl Option.
In the Properties window, select Calculated or User-Specified from the Fan Swirl Option drop-down menu.

If you select Calculated, the Fan Swirl node is added to the Physics Values.

If you select User-Specified, the Specified Fan Swirl node is added to the Physics Values.

In the Properties window, set the appropriate values.

Table 1. Fan Swirl Properties
Fan Efficiency	Specify the fan efficiency, $η$ in Eqn. (5028).
Coordinate System	Select the appropriate coordinate system. Types other than Laboratory are not available for selection until you create them. You can use any of the coordinate system types for fan modeling, but the following restrictions apply: The origin of the coordinate axes must coincide with the center of rotation of the fan. The z-axis must run along the fan axis and be oriented in the fan-flow direction.

Table 2. Specified Fan Swirl Properties
Method	Selects the input for the fan swirl value as a vector profile.
Dimensions	The units of the fan swirl value (read-only).
Coordinate System	Select the appropriate coordinate system. Types other than Laboratory are not available for selection until you create them. You can use any of the coordinate system types for fan modeling, but the following restrictions apply: The origin of the coordinate axes must coincide with the center of rotation of the fan. The z-axis must run along the fan axis and be oriented in the fan-flow direction.