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Radiation in semi-transparent media with surface-to-surface model? |
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June 2, 2015, 11:49
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Radiation in semi-transparent media with surface-to-surface model?
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#1 |
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New Member
Max
Join Date: Apr 2015
Posts: 14
Rep Power: 11  |
Hi everyone,
I'd like to model the radiation through a quartz glass plate that separates two fluid domains (fluid domains are set up with surface-to-surface MC radiation model). At the moment, all the information I have given about the glass is a transmissivity. I am doing a preliminary qualitative study, and I presume that the error I would make by neglecting the participating influence of the glass is well below the order of accuracy I am looking for right now. The question is though: Is it possible at all to do this set-up in CFX? I am a little lost, because choosing from the three options for a GGI between fluid domain and glass plate (Conservative Interface Flux: doesn't allow for any further specifications // Opaque: -> transimissvity=0 // Side-dependent: also only allows for 'Opaque' option on the domain-level boundary) I cannot find a possibility to specify a transimissivity. Thanks for your help! Best, Max |
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June 2, 2015, 22:28
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#2 |
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Senior Member
Join Date: Jun 2009
Posts: 1,880
Rep Power: 33 |
If you are modeling only the fluid domains, and separated by a thin wall and you would like to model the transmission through the glass as well, the answer is NO.
If you are modeling the fluid domains separated by a solid domain, you activate radiation in the solid, setup the properties for quartz (absorption coefficient, and refractive index). Then, you must use the Conservative Interface Flux boundary condition. As far as I understand, there is no such a thing as transmissivity for a substance. Emissivity, reflectivity, transmissivity and absorptivity are effective surface quantities, but not thermodynamic nor transport properties. If you can take a look at a radiative heat transfer textbook (say M. Modest book, or Siegel and Howell), you can see how to compute the effective transmissivity for a semi-transparent solid based on refractive indexes, and absorption coefficient. You can use such formulas to back out the "absorption coefficient" of quartz if you know the thickness for which the transmissivity was given. My 2 cents. |
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June 3, 2015, 13:01
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#3 |
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New Member
Max
Join Date: Apr 2015
Posts: 14
Rep Power: 11 |
Alright, thank you, I set it up with an absorption coefficient which corresponds to the transmittance (I accidentally called it transmissivity in the first post, thank you for noticing) I am given.
However, the solver cannot handle my setup and breaks down in coeff. loop 1 as it enters the MC-algorithm. I attached the CCL dscription of the three domains in question (fluid domains called 'FDS' and 'IC' and solid domain called 'Window' and their corresponding interfaces. Maybe you are willing to look through it and see if you find something suspicious because I did several times and couldn't figure out what's wrong here: FDS: Code:
FLOW: Flow Analysis 1
&replace DOMAIN: FDS
Coord Frame = Coord 0
Domain Type = Fluid
Location = VOLUMENK_RPER_1_1_SOLID
BOUNDARY: FDS_Wall_Adiabatic
Boundary Type = WALL
Create Other Side = Off
Interface Boundary = Off
Location = FDS_MANTLE_IN7,FDS_BOTTOM,FDS_MANTLE_IN6,FDS_TOP2,FDS_TOP1,FDS_MANTLE_OUT
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Option = Adiabatic
END
MASS AND MOMENTUM:
Option = No Slip Wall
END
THERMAL RADIATION:
Diffuse Fraction = 1.
Emissivity = 1.
Option = Opaque
END
WALL ROUGHNESS:
Option = Smooth Wall
END
END
END
BOUNDARY: FDS_Wall_Isothermal
Boundary Type = WALL
Create Other Side = Off
Interface Boundary = Off
Location = Primitive 2D H,Primitive 2D K,Primitive 2D B,Primitive 2D D,Primitive 2D F
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Fixed Temperature = Treactorwall
Option = Fixed Temperature
END
MASS AND MOMENTUM:
Option = No Slip Wall
END
THERMAL RADIATION:
Diffuse Fraction = 1.
Emissivity = 1.
Option = Opaque
END
WALL ROUGHNESS:
Option = Smooth Wall
END
END
END
BOUNDARY: FMDS_PER Side 1
Boundary Type = INTERFACE
Interface Boundary = t
Location = FDS_PER1
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Option = Conservative Interface Flux
END
MASS AND MOMENTUM:
Option = Conservative Interface Flux
END
THERMAL RADIATION:
Option = Conservative Interface Flux
END
TURBULENCE:
Option = Conservative Interface Flux
END
END
END
BOUNDARY: FMDS_PER Side 2
Boundary Type = INTERFACE
Interface Boundary = t
Location = FDS_PER2
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Option = Conservative Interface Flux
END
MASS AND MOMENTUM:
Option = Conservative Interface Flux
END
THERMAL RADIATION:
Option = Conservative Interface Flux
END
TURBULENCE:
Option = Conservative Interface Flux
END
END
END
BOUNDARY: GGI_FDS_WINDOW Side 1
Boundary Type = INTERFACE
Interface Boundary = t
Location = FDS_MANTLE_IN8
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Option = Conservative Interface Flux
END
MASS AND MOMENTUM:
Option = No Slip Wall
END
THERMAL RADIATION:
Option = Conservative Interface Flux
END
WALL ROUGHNESS:
Option = Smooth Wall
END
END
END
DOMAIN MODELS:
BUOYANCY MODEL:
Buoyancy Reference Density = 1.2922 [kg m^-3]
Gravity X Component = 0 [m s^-2]
Gravity Y Component = 0 [m s^-2]
Gravity Z Component = -9.81 [m s^-2]
Option = Buoyant
BUOYANCY REFERENCE LOCATION:
Option = Automatic
END
END
DOMAIN MOTION:
Option = Stationary
END
MESH DEFORMATION:
Option = None
END
REFERENCE PRESSURE:
Reference Pressure = 1 [atm]
END
END
FLUID DEFINITION: Fluid 1
Material = Air Ideal Gas
Option = Material Library
MORPHOLOGY:
Option = Continuous Fluid
END
END
FLUID MODELS:
COMBUSTION MODEL:
Option = None
END
HEAT TRANSFER MODEL:
Include Viscous Dissipation Term = On
Option = Thermal Energy
END
THERMAL RADIATION MODEL:
Number of Histories = 10000
Option = Monte Carlo
Radiation Transfer Mode = Surface to Surface
SCATTERING MODEL:
Option = None
END
SPECTRAL MODEL:
Option = Gray
END
END
TURBULENCE MODEL:
Option = k epsilon
BUOYANCY TURBULENCE:
Option = None
END
END
TURBULENT HEAT TRANSFER:
TURBULENT FLUX CLOSURE:
Option = Eddy Diffusivity
Turbulent Prandtl Number = 7.0462E-01
END
END
TURBULENT WALL FUNCTIONS:
Option = Scalable
END
END
INITIALISATION:
Option = Automatic
INITIAL CONDITIONS:
Velocity Type = Cartesian
CARTESIAN VELOCITY COMPONENTS:
Option = Automatic
END
RADIATION INTENSITY:
Option = Automatic
END
STATIC PRESSURE:
Option = Automatic
END
TEMPERATURE:
Option = Automatic
END
TURBULENCE INITIAL CONDITIONS:
Option = Medium Intensity and Eddy Viscosity Ratio
END
END
END
END
END
Code:
FLOW: Flow Analysis 1
&replace DOMAIN: IC
Coord Frame = Coord 0
Domain Type = Fluid
Location = VOLUMENK_RPER_1_1_SOLID 5
BOUNDARY: Domain Interface 1 Side 1
Boundary Type = INTERFACE
Interface Boundary = t
Location = IC_PER1
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Option = Conservative Interface Flux
END
MASS AND MOMENTUM:
Option = Conservative Interface Flux
END
THERMAL RADIATION:
Option = Conservative Interface Flux
END
TURBULENCE:
Option = Conservative Interface Flux
END
END
END
BOUNDARY: Domain Interface 1 Side 2
Boundary Type = INTERFACE
Interface Boundary = t
Location = IC_PER2
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Option = Conservative Interface Flux
END
MASS AND MOMENTUM:
Option = Conservative Interface Flux
END
THERMAL RADIATION:
Option = Conservative Interface Flux
END
TURBULENCE:
Option = Conservative Interface Flux
END
END
END
BOUNDARY: GGI_IC_EMITTER Side 1
Boundary Type = INTERFACE
Interface Boundary = t
Location = IC_BOTTOM
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Option = Conservative Interface Flux
END
MASS AND MOMENTUM:
Option = No Slip Wall
END
THERMAL RADIATION:
Diffuse Fraction = 1.
Emissivity = 1.
Option = Opaque
END
WALL ROUGHNESS:
Option = Smooth Wall
END
END
BOUNDARY SOURCE:
SOURCES:
RADIATION SOURCE: Radiation Source 1
Option = Isotropic Radiation Flux
Radiation Flux = RadSourceEmitter
END
END
END
END
BOUNDARY: GGI_WINDOW_IC Side 2
Boundary Type = INTERFACE
Interface Boundary = t
Location = IC_TOP
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Option = Conservative Interface Flux
END
MASS AND MOMENTUM:
Option = No Slip Wall
END
THERMAL RADIATION:
Option = Conservative Interface Flux
END
WALL ROUGHNESS:
Option = Smooth Wall
END
END
END
BOUNDARY: IC_Wall_Adiabatic
Boundary Type = WALL
Create Other Side = Off
Interface Boundary = Off
Location = Primitive 2D 5,Primitive 2D C 5,Primitive 2D E 2,Primitive 2D F 2,Primitive 2D H 2,Primitive 2D I 2,Primitive 2D J 2,Primitive 2D K 2,Primitive 2D L 2
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Option = Adiabatic
END
MASS AND MOMENTUM:
Option = No Slip Wall
END
THERMAL RADIATION:
Diffuse Fraction = 1.
Emissivity = 1.
Option = Opaque
END
WALL ROUGHNESS:
Option = Smooth Wall
END
END
BOUNDARY SOURCE:
SOURCES:
RADIATION SOURCE: Radiation Source 1
Option = Isotropic Radiation Flux
Radiation Flux = qiso
END
END
END
END
DOMAIN MODELS:
BUOYANCY MODEL:
Buoyancy Reference Density = 1.2922 [kg m^-3]
Gravity X Component = 0 [m s^-2]
Gravity Y Component = 0 [m s^-2]
Gravity Z Component = -9.81 [m s^-2]
Option = Buoyant
BUOYANCY REFERENCE LOCATION:
Option = Automatic
END
END
DOMAIN MOTION:
Option = Stationary
END
MESH DEFORMATION:
Option = None
END
REFERENCE PRESSURE:
Reference Pressure = 1 [atm]
END
END
FLUID DEFINITION: Fluid 1
Material = Air Ideal Gas
Option = Material Library
MORPHOLOGY:
Option = Continuous Fluid
END
END
FLUID MODELS:
COMBUSTION MODEL:
Option = None
END
HEAT TRANSFER MODEL:
Option = Total Energy
END
THERMAL RADIATION MODEL:
Number of Histories = 10000
Option = Monte Carlo
Radiation Transfer Mode = Surface to Surface
SCATTERING MODEL:
Option = None
END
SPECTRAL MODEL:
Option = Gray
END
END
TURBULENCE MODEL:
Option = SST
BUOYANCY TURBULENCE:
Option = None
END
END
TURBULENT WALL FUNCTIONS:
High Speed Model = Off
Option = Automatic
END
END
INITIALISATION:
Option = Automatic
INITIAL CONDITIONS:
Velocity Type = Cartesian
CARTESIAN VELOCITY COMPONENTS:
Option = Automatic
END
RADIATION INTENSITY:
Option = Automatic
END
STATIC PRESSURE:
Option = Automatic
END
TEMPERATURE:
Option = Automatic
END
TURBULENCE INITIAL CONDITIONS:
Option = Medium Intensity and Eddy Viscosity Ratio
END
END
END
END
END
Code:
FLOW: Flow Analysis 1
&replace DOMAIN: WINDOW
Coord Frame = Coord 0
Domain Type = Solid
Location = VOLUMENK_RPER_1_1_SOLID 4
BOUNDARY: GGI_FDS_WINDOW Side 2
Boundary Type = INTERFACE
Interface Boundary = t
Location = WINDOW_TOP
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Option = Conservative Interface Flux
END
THERMAL RADIATION:
Option = Conservative Interface Flux
END
END
END
BOUNDARY: GGI_WINDOW_IC Side 1
Boundary Type = INTERFACE
Interface Boundary = t
Location = WINDOW_BOTTOM
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Option = Conservative Interface Flux
END
THERMAL RADIATION:
Option = Conservative Interface Flux
END
END
END
BOUNDARY: WINDOW_PER Side 1
Boundary Type = INTERFACE
Interface Boundary = t
Location = WINDOW_PER1
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Option = Conservative Interface Flux
END
THERMAL RADIATION:
Option = Conservative Interface Flux
END
END
END
BOUNDARY: WINDOW_PER Side 2
Boundary Type = INTERFACE
Interface Boundary = t
Location = WINDOW_PER2
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Option = Conservative Interface Flux
END
THERMAL RADIATION:
Option = Conservative Interface Flux
END
END
END
BOUNDARY: WINDOW_Wall_Adiabatic
Boundary Type = WALL
Create Other Side = Off
Interface Boundary = Off
Location = Primitive 2D 4
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Option = Adiabatic
END
THERMAL RADIATION:
Diffuse Fraction = 1.
Emissivity = 1.
Option = Opaque
END
END
END
DOMAIN MODELS:
DOMAIN MOTION:
Option = Stationary
END
MESH DEFORMATION:
Option = None
END
END
INITIALISATION:
Option = Automatic
INITIAL CONDITIONS:
RADIATION INTENSITY:
Option = Automatic
END
TEMPERATURE:
Option = Automatic
END
END
END
SOLID DEFINITION: Solid 1
Material = QuartzGlass
Option = Material Library
MORPHOLOGY:
Option = Continuous Solid
END
END
SOLID MODELS:
HEAT TRANSFER MODEL:
Option = Thermal Energy
END
THERMAL RADIATION MODEL:
Number of Histories = 10000
Option = Monte Carlo
Radiation Transfer Mode = Participating Media
SCATTERING MODEL:
Option = None
END
SPECTRAL MODEL:
Option = Gray
END
END
END
END
END
Code:
FLOW: Flow Analysis 1
&replace DOMAIN INTERFACE: GGI_FDS_WINDOW
Boundary List1 = GGI_FDS_WINDOW Side 1
Boundary List2 = GGI_FDS_WINDOW Side 2
Filter Domain List1 = FDS
Filter Domain List2 = WINDOW
Interface Region List1 = FDS_MANTLE_IN8
Interface Region List2 = WINDOW_TOP
Interface Type = Fluid Solid
INTERFACE MODELS:
Option = General Connection
FRAME CHANGE:
Option = None
END
HEAT TRANSFER:
Option = Conservative Interface Flux
HEAT TRANSFER INTERFACE MODEL:
Option = None
END
END
PITCH CHANGE:
Option = None
END
THERMAL RADIATION:
Option = Conservative Interface Flux
END
END
MESH CONNECTION:
Option = GGI
END
END
&replace DOMAIN INTERFACE: GGI_WINDOW_IC
Boundary List1 = GGI_WINDOW_IC Side 1
Boundary List2 = GGI_WINDOW_IC Side 2
Filter Domain List1 = WINDOW
Filter Domain List2 = IC
Interface Region List1 = WINDOW_BOTTOM
Interface Region List2 = IC_TOP
Interface Type = Fluid Solid
INTERFACE MODELS:
Option = General Connection
FRAME CHANGE:
Option = None
END
HEAT TRANSFER:
Option = Conservative Interface Flux
HEAT TRANSFER INTERFACE MODEL:
Option = None
END
END
PITCH CHANGE:
Option = None
END
THERMAL RADIATION:
Option = Conservative Interface Flux
END
END
MESH CONNECTION:
Option = GGI
END
END
END
Best, Max |
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June 3, 2015, 14:49
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#4 |
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Senior Member
Join Date: Jun 2009
Posts: 1,880
Rep Power: 33 |
At a glance, it looks OK..
I noticed a few things: - Using different turbulence models for each fluid domain, did you turn off "constant domain physics" ? I understand you want to model two different fluids, and a non-trivial setup; however, it is better to know that it runs correctly for the same fluid on both sides with all the physics active, then change the fluid on 1 side - you are changing the Turbulent Prandtl Number. Do you really need to change such standard value ? Have you validated the heat transfer results for Pr_t = 0.7 ? It is an unusual value to me, and I would be worried about heat transfer results w/o proper validation (did you read CFX heat transfer validation presentation ? what wrong with it ? - The initial guess for temperature is automatic, I rather setup a isothermal flow everywhere first to see what happens.. As several in the forum advice, get a simpler version of your setup working and increase the complexity later. |
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June 4, 2015, 05:34
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#5 |
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New Member
Max
Join Date: Apr 2015
Posts: 14
Rep Power: 11 |
Thanks for your suggestions, Opaque, I cleaned up the setup and rerun the simulation, also with a smaller initial pseudo-time step and more MC-samples.
However the error message remains the same, all I can probably know from it is, that the problem is related to the way I set up the radiation model: Code:
+--------------------------------------------------------------------+ | Convergence History | +--------------------------------------------------------------------+ ====================================================================== | Timescale Information | ---------------------------------------------------------------------- | Equation | Type | Timescale | +----------------------+-----------------------+---------------------+ | T-Energy-WINDOW | Auto Timescale | 6.26301E+04 | | T-Energy-Emitter | Auto Timescale | 8.14351E+01 | +----------------------+-----------------------+---------------------+ ====================================================================== OUTER LOOP ITERATION = 1 CPU SECONDS = 2.100E+02 ---------------------------------------------------------------------- | Equation | Rate | RMS Res | Max Res | Linear Solution | +----------------------+------+---------+---------+------------------+ | Wallscale-FDS | 0.00 | 4.9E-01 | 1.0E+01 | 5.5 4.3E-07 OK| +----------------------+------+---------+---------+------------------+ | Wallscale-IC | 0.00 | 5.6E-01 | 1.0E+01 | 5.5 3.7E-07 OK| +----------------------+------+---------+---------+------------------+ | U-Mom-FDS | 0.00 | 0.0E+00 | 0.0E+00 | 0.0E+00 OK| | V-Mom-FDS | 0.00 | 0.0E+00 | 0.0E+00 | 0.0E+00 OK| | W-Mom-FDS | 0.00 | 6.1E-01 | 1.1E+01 | 9.7E-05 OK| | P-Mass-FDS | 0.00 | 1.5E-09 | 4.3E-08 | 41.9 1.9E+03 F | +----------------------+------+---------+---------+------------------+ | U-Mom-IC | 0.00 | 0.0E+00 | 0.0E+00 | 0.0E+00 OK| | V-Mom-IC | 0.00 | 0.0E+00 | 0.0E+00 | 0.0E+00 OK| | W-Mom-IC | 0.00 | 7.0E-01 | 1.1E+01 | 2.2E-04 OK| | P-Mass-IC | 0.00 | 1.9E-09 | 2.7E-08 | 42.5 1.1E+04 F | +----------------------+------+---------+---------+------------------+ | U-Mom-OC | 0.00 | 0.0E+00 | 0.0E+00 | 0.0E+00 OK| | V-Mom-OC | 0.00 | 0.0E+00 | 0.0E+00 | 0.0E+00 OK| | W-Mom-OC | 0.00 | 1.8E+00 | 1.2E+01 | 9.9E-05 OK| | P-Mass-OC | 0.00 | 1.5E-09 | 8.8E-09 | 43.3 9.7E+03 F | +----------------------+------+---------+---------+------------------+ Slave: 2 Slave: 3 Slave: 3 Details of error:- Slave: 3 ---------------- Slave: 3 Error detected by routine PSHDIR Slave: 3 CDRNAM = /FLOW/SOLUTION/LATEST/ZN5 /BELG3 Slave: 3 CRESLT = NONE Slave: 3 Slave: 3 Current Directory : /RADIATION/RG6 Slave: 4 Slave: 5 Slave: 5 Details of error:- Slave: 5 ---------------- Slave: 5 Error detected by routine PSHDIR Slave: 5 CDRNAM = /FLOW/SOLUTION/LATEST/ZN5 /BELG3 Slave: 5 CRESLT = NONE Slave: 5 Slave: 5 Current Directory : /RADIATION/RG6 Slave: 2 Details of error:- Slave: 2 ---------------- Slave: 2 Error detected by routine PSHDIR Slave: 2 CDRNAM = /FLOW/SOLUTION/LATEST/ZN5 /BELG4 Slave: 2 CRESLT = NONE Slave: 2 Slave: 2 Current Directory : /RADIATION/RG6 Slave: 6 Slave: 6 Details of error:- Slave: 6 ---------------- Slave: 6 Error detected by routine PSHDIR Slave: 6 CDRNAM = /FLOW/SOLUTION/LATEST/ZN5 /BELG4 Slave: 6 CRESLT = NONE Slave: 6 Slave: 6 Current Directory : /RADIATION/RG6 Slave: 4 Details of error:- Slave: 4 ---------------- Slave: 4 Error detected by routine PSHDIR Slave: 4 CDRNAM = /FLOW/SOLUTION/LATEST/ZN5 /BELG6 Slave: 4 CRESLT = NONE Slave: 4 Slave: 4 Current Directory : /RADIATION/RG6 Slave: 10 Slave: 10 Details of error:- Slave: 10 ---------------- Slave: 10 Error detected by routine PSHDIR Slave: 10 CDRNAM = /FLOW/SOLUTION/LATEST/ZN5 /BELG8 Slave: 10 CRESLT = NONE Slave: 10 Slave: 10 Current Directory : /RADIATION/RG6 Slave: 11 Slave: 11 Details of error:- Slave: 11 ---------------- Slave: 11 Error detected by routine PSHDIR Slave: 11 CDRNAM = /FLOW/SOLUTION/LATEST/ZN5 /BELG7 Slave: 11 CRESLT = NONE Slave: 11 Slave: 11 Current Directory : /RADIATION/RG6 Parallel run: Received message from slave ----------------------------------------- Slave partition : 3 Slave routine : ErrAction Master location : RCVBUF,MSGTAG=1012 Message label : 001100279 Message follows below - : +--------------------------------------------------------------------+ | ERROR #001100279 has occurred in subroutine ErrAction. | | Message: | | Stopped in routine MEMERR | | | | | | | | | | | +--------------------------------------------------------------------+ +--------------------------------------------------------------------+ | An error has occurred in cfx5solve: | | | | The ANSYS CFX solver exited with return code 1. No results file | | has been created. | +--------------------------------------------------------------------+ End of solution stage. Best, Max Edit: I noticed, I might provide the material definitions as well, maybe there is a problem i don't know about.. Code:
LIBRARY:
&replace MATERIAL: QuartzGlass
Material Group = User
Option = Pure Substance
Thermodynamic State = Solid
PROPERTIES:
Option = General Material
ABSORPTION COEFFICIENT:
Absorption Coefficient = 36.2853 [m^-1]
Option = Value
END
EQUATION OF STATE:
Density = 2200 [kg m^-3]
Molar Mass = 60.1 [g mol^-1]
Option = Value
END
REFERENCE STATE:
Option = Automatic
END
REFRACTIVE INDEX:
Option = Value
Refractive Index = 1.547
END
SCATTERING COEFFICIENT:
Option = Value
Scattering Coefficient = 0. [m^-1]
END
SPECIFIC HEAT CAPACITY:
Option = Value
Specific Heat Capacity = cpquartz
END
TABLE GENERATION:
Pressure Extrapolation = On
Temperature Extrapolation = Yes
END
THERMAL CONDUCTIVITY:
Option = Value
Thermal Conductivity = kquartz
END
END
END
END
Last edited by mpeppels; June 4, 2015 at 07:25. |
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June 4, 2015, 11:24
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#6 |
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Senior Member
Join Date: Jun 2009
Posts: 1,880
Rep Power: 33 |
Something is definitely wrong in the setup for the radiation boundary conditions.
To isolate the problem, you can try the following: 1 - Ignore the flow field solutions for now, i.e. EXPERT PARAMETERS: solve wallscale = f solve fluids = f END 2 - Deactivate radiation in the solid domain. Only leave heat transfer active. Modify boundary conditions at interface appropriately 3 - Run and check if you get at least 2 radiation solution equation sets as you did for the disconnected flow passages. If that still fails, activate radiation only 1 a single fluid domain until you get it to work. |
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June 8, 2015, 12:33
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#7 |
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New Member
Max
Join Date: Apr 2015
Posts: 14
Rep Power: 11 |
I tried different cases and everything works out, as long as the solid radiation model is deactivated.
But that only tells me that the solid radiation model contains the problem or did I miss the point in your suggestion? |
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June 8, 2015, 13:17
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#8 |
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Senior Member
Join Date: Jun 2009
Posts: 1,880
Rep Power: 33 |
What happens if you activate the radiation model in the solid, but still keep the domain interface boundaries as opaque, i.e. you should get 3 decoupled radiation problems to be solved.
If that works, the problem is with one of the domain interface boundaries. Try activating 1 at a time. What version of ANSYS CFX are you using ? |
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June 10, 2015, 13:07
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#9 |
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New Member
Max
Join Date: Apr 2015
Posts: 14
Rep Power: 11 |
I had technical problems yesterday but here I am again today:
Thanks for the debugging guidance so far, I found an interesting result: The 'malicious' interface isn't even a fluid-solid interface but just a periodicity condition I am using since my geometry is axially symmetric. I set up this kind of periodic interface for every single domain. Funnily, this is not causing any trouble with all the fluid domains with surface-to-surface radiation models. (However it is, with a solid domain surface-to-surface MC) Have you ever heard of a similiar problem? There isn't exactly much to do wrong with this kind of interface I guess, here it is: Domain Level: Code:
BOUNDARY: WINDOW_PER Side 1
Boundary Type = INTERFACE
Location = WINDOW_PER1
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Option = Conservative Interface Flux
END
THERMAL RADIATION:
Option = Conservative Interface Flux
END
END
END
BOUNDARY: WINDOW_PER Side 2
Boundary Type = INTERFACE
Location = WINDOW_PER2
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Option = Conservative Interface Flux
END
THERMAL RADIATION:
Option = Conservative Interface Flux
END
END
END
Code:
DOMAIN INTERFACE: WINDOW_PER
Boundary List1 = WINDOW_PER Side 1
Boundary List2 = WINDOW_PER Side 2
Interface Type = Solid Solid
INTERFACE MODELS:
Option = Rotational Periodicity
AXIS DEFINITION:
Option = Coordinate Axis
Rotation Axis = Coord 0.3
END
END
MESH CONNECTION:
Option = GGI
END
END
Max |
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June 10, 2015, 14:52
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#10 |
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Senior Member
Join Date: Jun 2009
Posts: 1,880
Rep Power: 33 |
I have not seen such error before.
Though the boundaries are part of a rotational periodic interface , I would try making them "SYMMETRY" boundaries on the solid domain to see if the error goes away. If the error goes away, it must be a bug in the software. Hope it helps, |
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June 16, 2015, 16:48
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#11 |
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New Member
Max
Join Date: Apr 2015
Posts: 14
Rep Power: 11 |
I used a symmetry condition which worked and subsequently tried the periodic condition again which worked as well.
Ripping the setup apart and rebuilding it from scratch might just have been the thing I needed here, even though I did an xxdiff on the solver input ccl of the erroneous version of which I posted the error messages above and the one I got to work now and there really was no difference in the PRE setup.. Result: confused user, resolved problem, alright... :-/ I'd like to ask one more quite basic question since I am new to radiation modelling in CFX and searched the CFX help pages for quite a while without finding anything concrete: If I define an isotropic radiation source on a fluid-solid interface (fluid: S2S radiation model/solid: no radiation model), I'll do it in the boundary condition in the fluid domain arising from the interface I defined. Now, I am wondering: what will the source be oriented like? flux from fluid towards solid at positive sign? I guess, I might have set up a simple test case to find out but I am faithful this easier way might work as well! (I take it, directional sources with specified flux vector override any kind of flux vector orientation convention?) Thanks in advance, Max |
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August 22, 2019, 08:30
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#12 | |
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Senior Member
Raza Javed
Join Date: Apr 2019
Location: Germany
Posts: 183
Rep Power: 7 |
Quote:
Hello, I am using chtMultiRegionSimpleFoam and my OpenFoam version is 4.1 My question is also related to the same topic. In my geometry I have two regions (as shown in the attached figure) specifications of my case: 1. Green region is heater. 2. Blue region is air 3. In the heater region, there is fvOptions with a power of 5W. 4. The air is not moving (frozenFlow=yes), to minimize the effect of convection. 5. In the heater region, I have put the radiation model= opaqueSolid. 6. In the air region, I have put the radiation model = viewFactor. 7. I am following the tutorial chtMultiRegionSimpleFoam/multiRegionHeaterRadiation. Trying to do: As due to power on the heater, its temperature would be higher as compared to air, so heat will radiate into the air, the goal is to simulate those radiations to check how fast the heat radiates, and how fast it goes to steady state? Questions: 1. Are the radiation models which I am using correct? Or do I need to use others? 2. When I remove the radiations from my case, even then I see the same results as with radiations. I don't know why is it like that? 3. What should I expect when I am using radiation? faster heat transfer? or something else? 4. With the case specifications, I mentioned above, when I RUN the case, the temperature of both (heater and air) starts continuously increasing and increasing. I don't know why ? because I am just putting 5W of power, the temperature should not go so high. 5. How can I calculate the temperature of my heater if I have the power dissipation of 5W? I tried to explain my problem and I shall be very thankful if you can help. Thank you |
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