CFX 5.5 V5.5.1H
? 2001AEA Technology
5-1
Domains
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-2
Introduction
? Domains represent 3D regions where governing equations are solved
Domains can be comprised of more than one solid joined together
Domains can also contain internal 3D regions
> Cutouts - solid obstacles to flow
> Sub-domains
* Fluid sub-domains,volumetric sources/sinks of mass,heat
and momentum
* Solid sub-domains,conjugate heat transfer
> Cutouts and sub-domains are defined using existing solids
? Domain/sub-domains are used to define the physical models and
physical properties for the CFX-5 simulations
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-3
Rules for Solids in Domains
? Each solid in the Domain/Sub-domain specification must be a valid CFX-
Build solid.
? Solids may not overlap one another.
? If there is more than one bounding solid defining the Domain/Sub-
domain,each solid must be connected at a common solid face (point or
edge contact is not allowed).
? Cutout solids must lie wholly within the regions defined by the bounding
solids of the Domain/Sub-domain,The connection of a cutout solid with
a bounding solid must be at a common solid face.
? Multiple cutout solids can be used,If cutout solids are connected to each
other they must do so at common solid faces.
? Sub-domains must lie wholly within the regions defined by the Domain,
The connection of a Sub-domain with a Domain must be at a common
solid face.
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-4
Rules for Solids in Domains
? Sub-domains may not be created within other Sub-domains
? Only one level of nesting is permitted i.e,you cannot create Domains
and Sub-domains within cutout solids
? These rules apply to both Fluid and Solid Sub-domains,and no
special consideration is needed for Solid Sub-domains
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-5
Examples for CFX-5 Topology
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-6
Examples for CFX-5 Topology
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-7
Examples for CFX-5 Topology
Case 3
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-8
Case 4
Examples for CFX-5 Topology
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-9
Domains
Domain name
Fluid models
Bounding solid(s)
Fluid editor
Cutout solid(s)
Domain options
Number of phases
Multiphase options
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-10
Domain Options
? Simulation type
Steady state
Transient
> Time steps
> Time duration
? Domain Motion
Stationary
Rotating
> Axis of rotation
> Angular velocity
? Reference frame
? Reference pressure
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-11
Fluids Editor
? The Fluids Editor is a tool which allows users to
create/edit/delete fluid definitions for use in the
simulation
? There is a clearly defined hierarchy to describe
the composition of fluids in a problem
A Domaincan contain one or more Fluids
A Fluid can contain one or more
Componentsin varying concentration
A Componentcan consist of one or more
Materialsin fixed concentration
A Materialdefines the physical properties
? A Fluid or Component can be given material
properties
? Each fluid can comprise up to ten components,
each component can comprise up to six
materials
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-12
? Example
? The Fluids Editor allows the user to define complex mixtures when
necessary,and simple ones when possible
Fluids Editor
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-13
Fluid Composition
? All component properties
are calculated as Ideal
Mixtures using the material
properties and their mass
fractions
? The properties of each fluid
is also calculated as an
Ideal Mixture of its
component
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-14
Pure Fluid Properties
? Properties can be specified
using several systems of units
? Properties can be constant or
specified as a function of other
variables through an
expression
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-15
Domain Density Form
? Accessed from the Properties
form
? Can be a function of temperature
and pressure
? Density may be modelled using
the ideal gas equation of state
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-16
Fluid Models (Single-phase)
? Turbulence model
Laminar
Zero equation model
k-e model / RNG k-e model
k-?
Shear Stress Transport
Reynolds stress model
SSG Reynolds Stress Model
QI Reynolds Stress Model
? Wall Functions
Scalable
Standard
? Heat Transfer model
None - energy equation not set
Isothermal - energy equation not solved
Thermal energy model - assumes total enthalpy
is equal to static enthalpy
Total energy model - includes kinetic term in
total enthalpy
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-17
Fluid Models (Single-phase)
? Buoyancy model
Gravity vector
Buoyancy reference
temperature/buoyancy
reference density
? Thermal Radiation Model
Rosseland
P1
? Multi-component model
? Additional scalar transport model
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-18
Multi-component Flows
? Multi-component flows
Transport equation,solve the
transport equation for the
component
> Use Bulk Viscosity or enter a
Kinematic Diffusivity
Algebraic equation,calculate the
mass fraction of the component
in the fluid using an algebraic
expression (CEL)
Constraint,make sure the mass
fractions of the components add
up to one
> One component must use a
constraint equation
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-19
Additional Variables
? Additional variables
Transport of passive scalar variables
(e.g,dye in water or smoke in air)
Created from the tools pull down menu
> Tools..Additional Variables Editor
Scalar type can be
> volumetric
* e.g.,mass concentration
> specific
* e.g.,mass fraction
> unspecified (no transport equation
solved)
* e.g.,mach number
Can be diffusive or non-diffusive
Equation Type
> Transport equation
* e.g.,dye in water
> Algebraic equation
* e.g.,total pressure
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-20
Sub-domains
? Sub-domains are regions within the domain where the following
may be defined
Momentum sources and sinks
Momentum linear and quadratic resistance terms
Mass sources and sinks
Energy sources and sinks
Conjugate heat transfer
? Source and sinks may be constants or variables
? There are two types of sub-domains,fluid sub-domains and solid
sub-domains
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-21
Fluid Sub-domains
? A fluid sub-domain is a fluid
3D region which can be used
to model fluid flow,heat
transfer and mass transfer
? Sources
Momentum source
Linear resistance
Quadratic resistance
Mass source
Mass source coefficient
Energy source
Energy linear coefficient
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-22
Solid Sub-domains
? A solid sub-domain is a solid
3D region which can be used
to model heat transfer but no
fluid flow (conjugate heat
transfer)
? Solid properties
Solid density
Solid thermal conductivity
Solid specific heat
? Template solid
Iron,rubber,steel,etc…
? Sources
Energy source
Energy linear source
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-23
Multiphase Flows
? A Multi-phase system is one which
contains more than one fluid in the
domain,In CFX-5,the terms Multi-
phase and Multi-fluid are
synonymous.
? Built-in models for interface drag.
? Special degassing boundary condition
for bubble column applications.
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-24
Fluid Models (Multi-phase)
? Turbulence model.
Laminar.
Zero equation model.
k-e model.
RNG k-e model.
Fluid-dependent turbulence model.
? Wall Functions.
Standard.
Scalable.
? Heat Transfer model.
None.
Isothermal.
Fluid-dependent heat transfer model.
? Buoyancy model.
? Thermal Radiation.
Radiation is not currently available
with Multi-Phase Flow.
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-25
Fluid Models (Multi-phase)
? Morphology
Continuous fluid
Dispersed fluid
Dispersed solid
Mean diameter for dispersed
fluid/solid
? Minimum volume fraction
Default
Specify Value
? Heat transfer model
None
Isothermal
Thermal Energy
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-26
Multiphase Options
? Fluid pair
? Interface transfer model
Particle model
Mixture model
> Interface length scale
? Surface Tension
Surface tension coefficient
? Drag force
Drag coefficient
Schiller Naumann
Wen Yu
Gidaspow
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-27
Multiphase Options
? Enhanced Turbulence Production Model
None
Sato Enhanced Eddy Viscosity Model
? Turbulent Dispersion Force
None
Lopez de Bertodano
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-28
Summary
? Domain
Topology requirement
? Fluid models
Steady state/transient flow
Single-phase/two-phase
Turbulent/laminar
(Conjugate) heat
transfer/isothermal
Compressible/incompressible
Buoyant/non-buoyant
Multi-components
Additional variables
? Fluid properties
Multi-fluid flows
Multi-component flows
? Sub-domains
Fluid sub-domains
Solid sub-domains
? 2001AEA Technology
5-1
Domains
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-2
Introduction
? Domains represent 3D regions where governing equations are solved
Domains can be comprised of more than one solid joined together
Domains can also contain internal 3D regions
> Cutouts - solid obstacles to flow
> Sub-domains
* Fluid sub-domains,volumetric sources/sinks of mass,heat
and momentum
* Solid sub-domains,conjugate heat transfer
> Cutouts and sub-domains are defined using existing solids
? Domain/sub-domains are used to define the physical models and
physical properties for the CFX-5 simulations
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-3
Rules for Solids in Domains
? Each solid in the Domain/Sub-domain specification must be a valid CFX-
Build solid.
? Solids may not overlap one another.
? If there is more than one bounding solid defining the Domain/Sub-
domain,each solid must be connected at a common solid face (point or
edge contact is not allowed).
? Cutout solids must lie wholly within the regions defined by the bounding
solids of the Domain/Sub-domain,The connection of a cutout solid with
a bounding solid must be at a common solid face.
? Multiple cutout solids can be used,If cutout solids are connected to each
other they must do so at common solid faces.
? Sub-domains must lie wholly within the regions defined by the Domain,
The connection of a Sub-domain with a Domain must be at a common
solid face.
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-4
Rules for Solids in Domains
? Sub-domains may not be created within other Sub-domains
? Only one level of nesting is permitted i.e,you cannot create Domains
and Sub-domains within cutout solids
? These rules apply to both Fluid and Solid Sub-domains,and no
special consideration is needed for Solid Sub-domains
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-5
Examples for CFX-5 Topology
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-6
Examples for CFX-5 Topology
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-7
Examples for CFX-5 Topology
Case 3
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-8
Case 4
Examples for CFX-5 Topology
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-9
Domains
Domain name
Fluid models
Bounding solid(s)
Fluid editor
Cutout solid(s)
Domain options
Number of phases
Multiphase options
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-10
Domain Options
? Simulation type
Steady state
Transient
> Time steps
> Time duration
? Domain Motion
Stationary
Rotating
> Axis of rotation
> Angular velocity
? Reference frame
? Reference pressure
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-11
Fluids Editor
? The Fluids Editor is a tool which allows users to
create/edit/delete fluid definitions for use in the
simulation
? There is a clearly defined hierarchy to describe
the composition of fluids in a problem
A Domaincan contain one or more Fluids
A Fluid can contain one or more
Componentsin varying concentration
A Componentcan consist of one or more
Materialsin fixed concentration
A Materialdefines the physical properties
? A Fluid or Component can be given material
properties
? Each fluid can comprise up to ten components,
each component can comprise up to six
materials
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-12
? Example
? The Fluids Editor allows the user to define complex mixtures when
necessary,and simple ones when possible
Fluids Editor
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-13
Fluid Composition
? All component properties
are calculated as Ideal
Mixtures using the material
properties and their mass
fractions
? The properties of each fluid
is also calculated as an
Ideal Mixture of its
component
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-14
Pure Fluid Properties
? Properties can be specified
using several systems of units
? Properties can be constant or
specified as a function of other
variables through an
expression
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-15
Domain Density Form
? Accessed from the Properties
form
? Can be a function of temperature
and pressure
? Density may be modelled using
the ideal gas equation of state
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-16
Fluid Models (Single-phase)
? Turbulence model
Laminar
Zero equation model
k-e model / RNG k-e model
k-?
Shear Stress Transport
Reynolds stress model
SSG Reynolds Stress Model
QI Reynolds Stress Model
? Wall Functions
Scalable
Standard
? Heat Transfer model
None - energy equation not set
Isothermal - energy equation not solved
Thermal energy model - assumes total enthalpy
is equal to static enthalpy
Total energy model - includes kinetic term in
total enthalpy
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-17
Fluid Models (Single-phase)
? Buoyancy model
Gravity vector
Buoyancy reference
temperature/buoyancy
reference density
? Thermal Radiation Model
Rosseland
P1
? Multi-component model
? Additional scalar transport model
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-18
Multi-component Flows
? Multi-component flows
Transport equation,solve the
transport equation for the
component
> Use Bulk Viscosity or enter a
Kinematic Diffusivity
Algebraic equation,calculate the
mass fraction of the component
in the fluid using an algebraic
expression (CEL)
Constraint,make sure the mass
fractions of the components add
up to one
> One component must use a
constraint equation
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-19
Additional Variables
? Additional variables
Transport of passive scalar variables
(e.g,dye in water or smoke in air)
Created from the tools pull down menu
> Tools..Additional Variables Editor
Scalar type can be
> volumetric
* e.g.,mass concentration
> specific
* e.g.,mass fraction
> unspecified (no transport equation
solved)
* e.g.,mach number
Can be diffusive or non-diffusive
Equation Type
> Transport equation
* e.g.,dye in water
> Algebraic equation
* e.g.,total pressure
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-20
Sub-domains
? Sub-domains are regions within the domain where the following
may be defined
Momentum sources and sinks
Momentum linear and quadratic resistance terms
Mass sources and sinks
Energy sources and sinks
Conjugate heat transfer
? Source and sinks may be constants or variables
? There are two types of sub-domains,fluid sub-domains and solid
sub-domains
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-21
Fluid Sub-domains
? A fluid sub-domain is a fluid
3D region which can be used
to model fluid flow,heat
transfer and mass transfer
? Sources
Momentum source
Linear resistance
Quadratic resistance
Mass source
Mass source coefficient
Energy source
Energy linear coefficient
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-22
Solid Sub-domains
? A solid sub-domain is a solid
3D region which can be used
to model heat transfer but no
fluid flow (conjugate heat
transfer)
? Solid properties
Solid density
Solid thermal conductivity
Solid specific heat
? Template solid
Iron,rubber,steel,etc…
? Sources
Energy source
Energy linear source
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-23
Multiphase Flows
? A Multi-phase system is one which
contains more than one fluid in the
domain,In CFX-5,the terms Multi-
phase and Multi-fluid are
synonymous.
? Built-in models for interface drag.
? Special degassing boundary condition
for bubble column applications.
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-24
Fluid Models (Multi-phase)
? Turbulence model.
Laminar.
Zero equation model.
k-e model.
RNG k-e model.
Fluid-dependent turbulence model.
? Wall Functions.
Standard.
Scalable.
? Heat Transfer model.
None.
Isothermal.
Fluid-dependent heat transfer model.
? Buoyancy model.
? Thermal Radiation.
Radiation is not currently available
with Multi-Phase Flow.
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-25
Fluid Models (Multi-phase)
? Morphology
Continuous fluid
Dispersed fluid
Dispersed solid
Mean diameter for dispersed
fluid/solid
? Minimum volume fraction
Default
Specify Value
? Heat transfer model
None
Isothermal
Thermal Energy
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-26
Multiphase Options
? Fluid pair
? Interface transfer model
Particle model
Mixture model
> Interface length scale
? Surface Tension
Surface tension coefficient
? Drag force
Drag coefficient
Schiller Naumann
Wen Yu
Gidaspow
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-27
Multiphase Options
? Enhanced Turbulence Production Model
None
Sato Enhanced Eddy Viscosity Model
? Turbulent Dispersion Force
None
Lopez de Bertodano
CFX 5.5 V5.5.1H
? 2001AEA Technology
5-28
Summary
? Domain
Topology requirement
? Fluid models
Steady state/transient flow
Single-phase/two-phase
Turbulent/laminar
(Conjugate) heat
transfer/isothermal
Compressible/incompressible
Buoyant/non-buoyant
Multi-components
Additional variables
? Fluid properties
Multi-fluid flows
Multi-component flows
? Sub-domains
Fluid sub-domains
Solid sub-domains
