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Файл:CFDModuleUsersGuide.pdf
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- •Why CFD is Important for Modeling
- •How the CFD Module Helps Improve Your Modeling
- •Model Builder Options for Physics Feature Node Settings Windows
- •Where Do I Access the Documentation and Model Library?
- •Typographical Conventions
- •Quick Start Guide
- •Modeling Strategy
- •Geometrical Complexities
- •Material Properties
- •Defining the Physics
- •Meshing
- •The Choice of Solver and Solver Settings
- •Coupling to Other Physics Interfaces
- •Adding a Chemical Species Transport Interface
- •Equation
- •Discretization
- •Transport Feature
- •Migration in Electric Field
- •Reactions
- •Reactions
- •Initial Values
- •Initial Values
- •Boundary Conditions for the Transport of Concentrated Species Interface
- •Mass Fraction
- •Mass Fraction
- •Flux
- •Inflow
- •Inflow
- •No Flux
- •Outflow
- •Flux Discontinuity
- •Flux Discontinuity
- •Symmetry
- •Open Boundary
- •Physical Model
- •Transport Properties
- •Model Inputs
- •Fluid Properties
- •Diffusion
- •Migration in Electric Field
- •Diffusion
- •Model Inputs
- •Density
- •Diffusion
- •Porous Matrix Properties
- •Porous Matrix Properties
- •Initial Values
- •Initial Values
- •Domain Features for the Reacting Flow, Concentrated Species Interface
- •Boundary Conditions for the Reacting Flow, Concentrated Species Interface
- •Reacting Boundary
- •Inward Flux
- •Physical Model
- •Transport Properties
- •Fluid Properties
- •Migration in Electric Field
- •Porous Matrix Properties
- •Initial Values
- •Domain Features for the Reacting Flow, Diluted Species Interface
- •Boundary Conditions for the Reacting Flow, Diluted Species Interface
- •Pair and Point Conditions for the Reacting Flow, Diluted Species Interface
- •Multicomponent Mass Transport
- •Multicomponent Diffusion: Mixture-Average Approximation
- •Multispecies Diffusion: Fick’s Law Approximation
- •Multicomponent Thermal Diffusion
- •References for the Transport of Concentrated Species Interface
- •Domain Equations
- •Combined Boundary Conditions
- •Effective Mass Transport Parameters in Porous Media
- •Selecting the Right Interface
- •The Single-Phase Flow Interface Options
- •Laminar Flow
- •Coupling to Other Physics Interfaces
- •The Laminar Flow Interface
- •Discretization
- •The Creeping Flow Interface
- •Discretization
- •Fluid Properties
- •Fluid Properties
- •Mixing Length Limit
- •Volume Force
- •Volume Force
- •Initial Values
- •Initial Values
- •The Turbulent Flow, Spalart-Allmaras Interface
- •The Rotating Machinery, Laminar Flow Interface
- •Rotating Domain
- •Rotating Domain
- •Initial Values
- •Initial Values
- •Rotating Wall
- •Wall
- •Boundary Condition
- •Interior Wall
- •Boundary Condition
- •Inlet
- •Boundary Condition
- •Velocity
- •Pressure, No Viscous Stress
- •Normal Stress
- •Outlet
- •Boundary Condition
- •Pressure
- •Laminar Outflow
- •No Viscous Stress
- •Vacuum Pump
- •Symmetry
- •Open Boundary
- •Boundary Stress
- •Boundary Condition
- •Periodic Flow Condition
- •Flow Continuity
- •Pressure Point Constraint
- •Non-Newtonian Flow—The Power Law and the Carreau Model
- •Theory for the Pressure, No Viscous Stress Boundary Condition
- •Theory for the Laminar Inflow Condition
- •Theory for the Laminar Outflow Condition
- •Theory for the Slip Velocity Wall Boundary Condition
- •Theory for the Vacuum Pump Outlet Condition
- •Theory for the No Viscous Stress Condition
- •Theory for the Mass Flow Inlet Condition
- •Turbulence Modeling
- •Eddy Viscosity
- •Wall Functions
- •Initial Values
- •Wall Distance
- •Inlet Values for the Turbulence Length Scale and Intensity
- •Initial Values
- •The Spalart-Allmaras Turbulence Model
- •Inlet Values for the Turbulence Length Scale and Intensity
- •Pseudo Time Stepping for Turbulent Flow Models
- •References for the Single-Phase Flow, Turbulent Flow Interfaces
- •Selecting the Right Interface
- •Coupling to Other Physics Interfaces
- •Discretization
- •Fluid-Film Properties
- •Initial Values
- •Initial Values
- •Inlet
- •Outlet
- •Wall
- •Symmetry
- •Discretization
- •Initial Values
- •Initial Values
- •Fluid-Film Properties
- •Border
- •Inlet
- •Outlet
- •Conditions for Film Damping
- •The Reynolds Equation
- •Structural Loads
- •Gas Outflow Conditions
- •Rarefaction and Slip Effects
- •Geometry Orientations
- •References for the Thin-Film Flow Interfaces
- •Selecting the Right Interface
- •The Multiphase Flow Interface Options
- •The Relationship Between the Interfaces
- •Bubbly Flow
- •Coupling to Other Physics Interfaces
- •The Laminar Two-Phase Flow, Level Set Interface
- •Discretization
- •The Laminar Two-Phase Flow, Phase Field Interface
- •Domain Level Settings for the Level Set and Phase Field Interfaces
- •Fluid Properties
- •Mixing Length Limit
- •Initial Values
- •Initial Values
- •Volume Force
- •Volume Force
- •Gravity
- •Boundary Conditions for the Level Set and Phase Field Interfaces
- •Wall
- •Boundary Condition
- •Initial Interface
- •The Turbulent Flow, Two-Phase Flow, Level Set Interface
- •The Turbulent Two-Phase Flow, Phase Field Interface
- •Wall Distance Interface and the Distance Equation
- •Level Set and Phase Field Equations
- •Conservative and Non-Conservative Formulations
- •Phase Initialization
- •Numerical Stabilization
- •References for the Level Set and Phase Field Interfaces
- •Stabilization
- •Discretization
- •Level Set Model
- •Initial Values
- •Initial Values
- •Boundary Conditions for the Level Set Function
- •Inlet
- •Initial Interface
- •No Flow
- •Outlet
- •Symmetry
- •Discretization
- •Initial Values
- •Initial Values
- •Phase Field Model
- •Boundary Conditions for the Phase Field Function
- •Initial Interface
- •Inlet
- •Wetted Wall
- •Wetted Wall
- •Outlet
- •The Level Set Method
- •Conservative and Non-Conservative Form
- •Initializing the Level Set Function
- •Variables For Geometric Properties of the Interface
- •Reference for the Level Set Interface
- •About the Phase Field Method
- •The Equations for the Phase Field Method
- •Conservative and Non-Conservative Forms
- •Additional Sources of Free Energy
- •Variables and Expressions
- •Reference For the Phase Field Interface
- •The Laminar Bubbly Flow Interface
- •Reference Pressure
- •Discretization
- •The Turbulent Bubbly Flow Interface
- •Reference Pressure
- •Discretization
- •Fluid Properties
- •Slip Model
- •Initial Values
- •Initial Values
- •Volume Force
- •Volume Force
- •Gravity
- •Gravity
- •Mass Transfer
- •Mass Transfer
- •Boundary Conditions for the Bubbly Flow Interfaces
- •Wall
- •Liquid Boundary Condition
- •Gas Boundary Condition
- •Inlet
- •Liquid Boundary Condition
- •Gas Boundary Condition
- •Outlet
- •Liquid Boundary Condition
- •Gas Boundary Condition
- •Symmetry
- •Gas Boundary Conditions Equations
- •The Mixture Model, Laminar Flow Interface
- •Stabilization
- •Discretization
- •The Mixture Model, Turbulent Flow Interface
- •Stabilization
- •Mixture Properties
- •Mass Transfer
- •Mass Transfer
- •Initial Values
- •Initial Values
- •Volume Force
- •Volume Force
- •Gravity
- •Gravity
- •Boundary Conditions for the Mixture Model Interfaces
- •Wall
- •Mixture Boundary Condition
- •Dispersed Phase Boundary Condition
- •Inlet
- •Mixture Boundary Condition
- •Dispersed Phase Boundary Condition
- •Outlet
- •Mixture Boundary Condition
- •Symmetry
- •The Bubbly Flow Equations
- •Turbulence Modeling in Bubbly Flow Applications
- •References for the Bubbly Flow Interfaces
- •The Mixture Model Equations
- •Dispersed Phase Boundary Conditions Equations
- •Turbulence Modeling in Mixture Models
- •Slip Velocity Models
- •References for the Mixture Model Interfaces
- •Dispersed Phase
- •Discretization
- •Domain Conditions for the Euler-Euler Model, Laminar Flow Interface
- •Phase Properties
- •Solid Viscosity Model
- •Drag Model
- •Solid Pressure Model
- •Initial Values
- •Boundary, Point, and Pair Conditions for the Euler-Euler Model, Laminar Flow Interface
- •Wall
- •Dispersed Phase Boundary Condition
- •Inlet
- •Two-Phase Inlet Type
- •Continuous Phase
- •Dispersed Phase
- •Outlet
- •Mixture Boundary Condition
- •The Euler-Euler Model Equations
- •References for the Euler-Euler Model, Laminar Flow Interface
- •Selecting the Right Interface
- •The Porous Media Flow Interface Options
- •Coupling to Other Physics Interfaces
- •Discretization
- •Fluid and Matrix Properties
- •Mass Source
- •Mass Source
- •Initial Values
- •Initial Values
- •Boundary Conditions for the Darcy’s Law Interface
- •Pressure
- •Pressure
- •Mass Flux
- •Mass Flux
- •Inflow Boundary
- •Inflow Boundary
- •Symmetry
- •No Flow
- •Discretization
- •Fluid and Matrix Properties
- •Volume Force
- •Volume Force
- •Forchheimer Drag
- •Forchheimer Drag
- •Initial Values
- •Initial Values
- •Mass Source
- •Boundary Conditions for the Brinkman Equations Interface
- •Discretization
- •Fluid Properties
- •Porous Matrix Properties
- •Porous Matrix Properties
- •Forchheimer Drag
- •Forchheimer Drag
- •Volume Force
- •Volume Force
- •Initial Values
- •Initial Values
- •Boundary Conditions for the Free and Porous Media Flow Interface
- •Microfluidic Wall Conditions
- •Boundary Condition
- •Discretization
- •Domain, Boundary, and Pair Conditions for the Two-Phase Darcy’s Law Interface
- •Fluid and Matrix Properties
- •Initial Values
- •Initial Values
- •No Flux
- •Pressure and Saturation
- •Pressure and Saturation
- •Mass Flux
- •Inflow Boundary
- •Inflow Boundary
- •Outflow
- •Pressure
- •Darcy’s Law—Equation Formulation
- •About the Brinkman Equations
- •Brinkman Equations Theory
- •References for the Brinkman Equations Interface
- •Reference for the Free and Porous Media Flow Interface
- •Darcy’s Law—Equation Formulation
- •The High Mach Number Flow, Laminar Flow Interface
- •Surface-to-Surface Radiation
- •Discretization
- •Initial Values
- •Initial Values
- •Shared Interface Features
- •Fluid
- •Dynamic Viscosity
- •Inlet
- •Outlet
- •Consistent Inlet and Outlet Conditions
- •Pseudo Time Stepping for High Mach Number Flow Models
- •References for the High Mach Number Flow Interfaces
- •Selecting the Right Interface
- •The Non-Isothermal Flow Interface Options
- •Coupling to Other Physics Interfaces
- •The Non-Isothermal Flow, Laminar Flow Interface
- •Discretization
- •The Conjugate Heat Transfer, Laminar Flow Interface
- •The Turbulent Flow, Spalart-Allmaras Interface
- •Fluid
- •Dynamic Viscosity
- •Wall
- •Boundary Condition
- •Initial Values
- •Pressure Work
- •Viscous Heating
- •Dynamic Viscosity
- •Turbulent Non-Isothermal Flow Theory
- •References for the Non-Isothermal Flow and Conjugate Heat Transfer Interfaces
- •Selecting the Right Interface
- •The Heat Transfer Interface Options
- •Conjugate Heat Transfer, Laminar Flow
- •Conjugate Heat Transfer, Turbulent Flow
- •Coupling to Other Physics Interfaces
- •Accessing the Heat Transfer Interfaces via the Model Wizard
- •Discretization
- •Heat Transfer in Solids
- •Translational Motion
- •Translational Motion
- •Pressure Work
- •Heat Transfer in Fluids
- •Viscous Heating
- •Dynamic Viscosity
- •Heat Source
- •Heat Source
- •Initial Values
- •Initial Values
- •Boundary Conditions for the Heat Transfer Interfaces
- •Temperature
- •Temperature
- •Thermal Insulation
- •Outflow
- •Symmetry
- •Heat Flux
- •Heat Flux
- •Inflow Heat Flux
- •Inflow Heat Flux
- •Open Boundary
- •Periodic Heat Condition
- •Surface-to-Ambient Radiation
- •Boundary Heat Source
- •Boundary Heat Source
- •Heat Continuity
- •Pair Thin Thermally Resistive Layer
- •Pair Thin Thermally Resistive Layer
- •Thin Thermally Resistive Layer
- •Thin Thermally Resistive Layer
- •Line Heat Source
- •Line Heat Source
- •Point Heat Source
- •Convective Cooling
- •Out-of-Plane Convective Cooling
- •Upside Heat Flux
- •Out-of-Plane Radiation
- •Upside Parameters
- •Out-of-Plane Heat Flux
- •Domain Selection
- •Upside Inward Heat Flux
- •Change Thickness
- •Change Thickness
- •Porous Matrix
- •Heat Transfer in Fluids
- •Thermal Dispersion
- •Dispersivities
- •Heat Source
- •Equation Formulation
- •Activating Out-of-Plane Heat Transfer and Thickness
M I X I N G L E N G T H L I M I T
|
This section is only available for the Turbulent Flow, k- interface, the |
|
Turbulent Flow, k- interface and the Rotating Machinery, Turbulent Flow |
Note |
k- interface, because it requires an upper limit on the mixing length. |
Select how the Mixing length limit lmix,lim (SI unit: m) is defined—Automatic (default) or Manual:
•If Automatic (the default) is used, the mixing length limit is automatically evaluated as the shortest side of the geometry bounding box. If the geometry is, for example, a complicated system of slim entities, this measure can give too big a result. In this case, it is recommended that it is defined manually.
•Select Manual to define a different value or expression.
Volume Force
The Volume Force feature specifies the volume force F on the right-hand side of the incompressible flow equation. Use it, for example, to incorporate the effects of gravity in your model.
ut + u u = – pI + u + u T + F
D O M A I N S E L E C T I O N
From the Selection list, choose the domains where the volume force acts on the fluid.
V O L U M E F O R C E
Enter the components of the Volume force F (SI unit: N/m3).
• The Boussinesq Approximation in the COMSOL Multiphysics User’s
Guide
See Also
96 | C H A P T E R 4 : S I N G L E - P H A S E F L O W B R A N C H
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