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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.
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).
DFBI Workflow
A DFBI (Dynamic Fluid Body Interaction) motion, different from a prescribed motion, solves the 6-DOF body movements resulting from the surrounding flow as well as the additional forces and moment. To set up a DFBI simulation, you first define a DFBI motion, set up a 6-DOF body, and then choose a simulation approach which realizes the movement of your 6-DOF body.
Adding a Superposed Motion to a 6-DOF Body
Simcenter STAR-CCM+ allows you to superpose prescribed rotations and translations onto the motion of a 6-DOF body, with multiple levels of nested motions.

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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).
  - Body Motion Options
    For a 6-DOF body, Simcenter STAR-CCM+ provides several body motion options by which you can specify an efficient motion description for a certain application.
  - Body Position and Body Local Coordinate System
    Simcenter STAR-CCM+ automatically creates a new Cartesian coordinate system with the default name Body n-CSys when a new 6-DOF body with the name Body n is created. This coordinate system (which can be referred to as the Body Local Coordinate System) moves together with the 6-DOF body and shows the current body position and orientation throughout the simulation.
  - Body Couplings
    Body couplings model the different types of connection between 6-DOF bodies or between a 6-DOF body and the environment. For each body coupling, an extra force is generated on each of the associated bodies.
  - Body Constraints
    A 6-DOF Body Constraint imposes kinematical constraints on the motion of a body. Constraints require that you activate the Multi-Body Motion option for the body.
  - Body Motion, Follow Motion, and Superposing Motion
    Simcenter STAR-CCM+ allows you to define complex motions with respect to the motion of a 6-DOF body. For example, you can superpose prescribed rotations and translations onto the motion of a 6-DOF body or create a motion that follows the motion of a 6-DOF body in some directions.
  - DFBI Workflow
    A DFBI (Dynamic Fluid Body Interaction) motion, different from a prescribed motion, solves the 6-DOF body movements resulting from the surrounding flow as well as the additional forces and moment. To set up a DFBI simulation, you first define a DFBI motion, set up a 6-DOF body, and then choose a simulation approach which realizes the movement of your 6-DOF body.
    - Combining DFBI Motion with Overset
      When used in conjunction with the overset mesh technique, the DFBI motion drives the overset region that contains the DFBI body. For DFBI embedded rotation, the DFBI motion additionally drives the background region.
    - Combining DFBI Motion with Morphing
      Morphing is a mesh method which displaces mesh vertices relative to region boundaries. It can be applied for executing the movement of the 6-DOF body.
    - Using DFBI Embedded Motion with Sliding Interface
      A sliding interface is an internal boundary interface which connects two regions rotating differently. The interface is updated within each inner iteration to exchange the data between the two regions.
    - Creating a 6-DOF Body
      After assigning an appropriate motion to the target region, you can proceed to create a 6-DOF body.
    - Coupling DFBI Bodies
      DFBI body couplings define body-to-body and body-to-environment coupling elements. There are 6 pre-defined and one user defined coupling types.
    - Setting Up Multi-Body Motion
      Multi-body motion allows you to simulate one or more 6-DOF bodies connected through mechanical joints or with their motions limited by mechanical constraints. It can also be used to compute single body motion, if the motion can not be simulated by free motion.
    - Setting Up Body Constraints
      Simcenter STAR-CCM+ supports three constraint types—Contact Constraint, Velocity Driver, and Distance Driver for 3D bodies with Multi-Body Motion option.
    - Adding a Superposed Motion to a 6-DOF Body
      Simcenter STAR-CCM+ allows you to superpose prescribed rotations and translations onto the motion of a 6-DOF body, with multiple levels of nested motions.
    - Defining Motion that Follows a 6-DOF Body
      A follow motion allows you to move a region together with a 6-DOF body and specify the directions in which the region follows the body.
    - Setting up a 2D DFBI Simulation
      Some DFBI applications can be modeled in 2D, providing a more computationally-efficient solution compared with simulating in full 3D coordinates. One such example—One-DOF Rotating Motion for 2D set-ups—was introduced in Simcenter STAR-CCM+ 12.04 to simulate rotating electric machines. There are now three additional 2D motions available—including one for axisymmetric set-ups.
    - Setting up DFBI Post-Processing
      DFBI solves for transient movements of 6-DOF bodies. To post-process DFBI results, you create DFBI reports and displayers.
  - DFBI Reference
    For the DFBI model, refer to the following topics to set up the properties:
- 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.

Adding a Superposed Motion to a 6-DOF Body

Simcenter STAR-CCM+ allows you to superpose prescribed rotations and translations onto the motion of a 6-DOF body, with multiple levels of nested motions.

Superposing motions let you model applications with multiple rotational motions. You typically use superposing motions in simulations with multiple regions such as a rotating propeller attached to a marine vessel. The system propeller + vessel moves rigidly in response to the applied fluid forces. Additionally, the propeller has a prescribed rotation motion. In this case, the fluid region around the vessel moves according to the calculated 6-DOF motion, whereas the fluid region around the propeller moves rigidly according to the calculated motion with the additional prescribed rotation.

The following steps outline the workflow defining a 6-DOF superposed motion:

Create multiple regions according to the applied simulation approach.
Define a DFBI Motion out of:
- DFBI Rotation and Translation
- DFBI Morphing
- DFBI Embedded Rotation

To assign the DFBI motion to the region containing the 6-DOF body, for example the marine vessel:

Select the Regions > [Region 1] > Physics Values > Motion Specification node and set Motion to the DFBI motion defined in the previous step.
DFBI node appears in the simulation tree.
Create a 6-DOF Body and set the properties. See also: Creating a 6-DOF Body
To create a body motion, right-click the DFBI > 6-DOF Bodies > [Body 1] node and select Create Body Motion.

The Tools > Motions > [Body 1]-Motion node is created.

To create a superposed motion, right-click the Tools > Motions > [Body 1]-Motion > Superposing Motions node, select New and choose the option Rotation or Translation, as appropriate.

Note	Do not use any DFBI report to set up a superposing motion. Due to the sequential of updating motion values, you should avoid setting up motions with transient motion data out of the simulation.

To assign the superposed motion to the region containing the boundaries with superposed rotation, for example the rotating propeller:

Navigate to the superposed region, and select the Regions > [Region 1] > Physics Values > Motion Specification and set Motion to Motion of Body 1 -> Rotation or [Body 1]-Motion -> Translation for other applications.