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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.
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.
Heat Exchangers
Heat Exchangers in Simcenter STAR-CCM+ model the heat transfer between two fluid streams—a hot and a cold stream (such as in radiators and air coolers). This section describes how to use the single stream and dual stream heat exchanger options in Simcenter STAR-CCM+.
Dual Stream Heat Exchangers
Two versions of the dual stream heat exchanger option exist in Simcenter STAR-CCM+: basic and actual.
Basic and Actual Dual Stream Heat Exchanger Options
The basic and actual dual stream heat exchanger options use different approaches for the solution.

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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.
  - Heat Conduction
    Heat conduction is the flow of internal energy from a region of higher temperature to a region of lower temperature by the interaction of the adjacent particles (for example, atoms, molecules, ions, or electrons) in the intervening space. This flow can be viewed as the transfer of energy from the more energetic particles to the less energetic particles of a substance due to interactions between the particles.
  - Convective Heat Transfer
    Convective heat transfer is the transfer of thermal energy by the movement of a fluid. In engineering practice, it is used to provide specific temperature changes. Examples include heat exchangers, electronic device cooling, and cooling of turbine blades.
  - Thermal Radiation
    Thermal radiation is the emission of electromagnetic waves from all matter that has a temperature greater than absolute zero, and represents a conversion of thermal energy into electromagnetic energy. It is generated by the thermal motion of charged particles in matter, which results in charge-acceleration and dipole oscillation. This drives the electrodynamic generation of coupled electric and magnetic fields, which cause the emission of thermal radiation.
  - Heat Transfer in Solids
    Simcenter STAR-CCM+ solves the governing equation for energy transport within a solid using either the finite volume method or the finite element method.
  - Conjugate Heat Transfer
    Simcenter STAR-CCM+ allows you to model the simultaneous, coupled heat transfer between a fluid and an adjoining solid via a solid-fluid interface. The following diagram shows an example application where you calculate the heat transfer between a fluid flowing inside of a solid pipe.
  - Thermal Comfort
    Thermal comfort refers to the level of satisfaction that a human has with the environmental conditions in his or her surroundings. Achieving and maintaining thermal comfort is a key goal of HVAC (Heating, Ventilation, and Air-Conditioning) system design and operation.
  - Guidelines for Heat Transfer Coefficients
    This section discusses the recommendations for accurate use of the Standard Wall Functions and the built-in post-processing heat transfer coefficients.
  - Boiling
    Boiling is a rapid vaporization of a liquid. It typically takes place when a liquid is heated up to temperatures that exceed the boiling temperature of the liquid.
  - Thin Film: Deicing and Defogging
    The Thin Film model provides a simplified approach for simulating deicing or defogging inside a cabin windshield or other surface. It addresses cases where the only features of interest about the ice or fog layer are where the layer is distributed and how thick it is. It assumes that the thickness is negligible compared to cell size.
  - Heat Exchangers
    Heat Exchangers in Simcenter STAR-CCM+ model the heat transfer between two fluid streams—a hot and a cold stream (such as in radiators and air coolers). This section describes how to use the single stream and dual stream heat exchanger options in Simcenter STAR-CCM+.
    - Single Stream Heat Exchangers
      In a single stream heat exchanger, one stream is assumed to have a uniform temperature and the other stream is modeled by specifying the heat exchanger enthalpy source.
    - Dual Stream Heat Exchangers
      Two versions of the dual stream heat exchanger option exist in Simcenter STAR-CCM+: basic and actual.
      - Basic and Actual Dual Stream Heat Exchanger Options
        The basic and actual dual stream heat exchanger options use different approaches for the solution.
      - Modeling Dual-Stream Heat Exchangers
        To use the dual-stream heat exchanger option, you must define the interface between two streams using a common mesh and separate physics continua. One physics continuum represents the hot stream, and the other represents the cold stream.
      - Heat Exchanger Interface Reference
        The heat exchanger interface becomes available as described in "Modeling Dual-Stream Heat Exchangers," Step 6.
  - Designing a Heat Transfer Optimization Study
    In mathematics, optimization is the selection of the best element (with respect to some criteria) from a set of available alternatives. In the simplest case, an optimization problem consists of maximizing or minimizing a real function (that is, the objective function) by systematically choosing input values from within an allowed set and computing the value of the function.
  - Energy Reference
    This section provides reference information that is common to the energy models in Simcenter STAR-CCM+.
  - Fluid Energy Reference
  - Solid Energy Reference
  - Heat Transfer Field Functions Reference
  - Energy Formulation
- 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.

Basic and Actual Dual Stream Heat Exchanger Options

The basic and actual dual stream heat exchanger options use different approaches for the solution.

The basic option solves for a simpler version of the energy equation, Eqn. (1657). The simpler version only uses the convective term and the source term to yield a solution independent of the solution that is generated for the overall simulation. This separate solution consists of pseudo-temperatures for the hot and cold regions of the heat exchanger, which are used to compute the mean temperature difference and hence the local heat transfer coefficient, UAL.
In order to compute the mean temperature difference and hence the UAL, the actual option uses the flow and energy values that are calculated for the simulation itself.

The basic option uses a wider range of properties settings than the actual. Specifics are given in the descriptions of affected objects.

When using the basic option, ensure that the core mesh is constructed of uniform cells. That is, all the cells in the heat exchanger region must be of comparable cell volume, as the cell volumes do not enter the calculation of the UAL table in the basic model. This restriction does not apply when using the actual option.

Note	UA refers to the product of the Overall heat transfer coefficient (U) and the Area of the heat exchanger (A), specified in W/K. UAL refers to the local (or cell value of) heat transfer coefficient (in W/K), with L referring to local.