GETVAR Error in Multiband Monte Carlo Radiation Simulation with Directional Source

silvan · June 14, 2014, 03:45

Dear experts,

I am modeling a solar reactor in CFX using the Monte Carlo ray tracing model. Simplified, the reactor is a quartz window (semitransparent) with incoming solar radiation which is followed by some kind of cavity where the reaction takes place.
There's a directional radiation source at the window. The window is modeled as participating media, the fluid inside the reactor is not (S2S only).
So far, I have managed to run many steady state simulations without any spectral dependency of the radiation (i.e. gray properties). Now, I would like to include spectral dependent properties for the window. Thus, the model is completed with the multiband model. There are two bands. The reason for the two bands is that the absorption coefficient and the refractive index of the window changes at a specific frequency and the directional source is only present in one of the bands.
Now, the issue is that the simulation runs perfectly until the monte carlo algorithm is called (every 5th iteration). Then the following error appears:

Code:

Slave:   4  Error in subroutine  CEL_GETVAR :
Slave:   4  Failed to get band definition for variable needed by Expression Language 
Slave:   4  GETVAR originally called by subroutine  ASS_RADSRC_FCS

I searched all of the ANSYS support platform, the documentation, this forum but I could not make any sense of this error. I guess it has to deal with the radiation source (because of "RADSRC"). But, I am not sure about this.

Please shed some light on this issue. I would be very happy to receive useful suggestions!!!
Thanks in advance!
Silvan

For more details I enclose a snippet of the CCL:

Code:

freqhigh = clight / 0.1 [micron]
freqlow = clight / 1000 [micron]
freqmid = clight / 3.697 [micron]
abscoeff = if( Frequency >= freqmid, 4.8 [m^-1], 925.6 [m^-1])
refrindex = if( Frequency >= freqmid, 1.454, 1.265)

radiationsource3r = if( Frequency >= freqmid, -5.85678e8 [W/m^5] * r^3 + 5.42330e7 [W/m^4] * r ^2 + 4.84790e5 [W/m^3] * r + 2.09385e5 [W/m^2], 0 [W/m^2])
radiationsource3z = if( Frequency >= freqmid, if(Z Coordinate >= 0.21 [m], 1.77946e6 [W/m^3] * Z Coordinate - 3.21676e5 [W/m^2], 0 [W/m^2]), 0 [W/m^2])

...

   MATERIAL: QUARTZ
     Material Group = User
     Option = Pure Substance
     Thermodynamic State = Solid
     PROPERTIES:
       Option = General Material
       EQUATION OF STATE:
         Density = 2500 [kg m^-3]
         Molar Mass = 1.0 [kg kmol^-1]
         Option = Value
       END
       SPECIFIC HEAT CAPACITY:
         Option = Value
         Specific Heat Capacity = CpQuartz
       END
       TABLE GENERATION:
         Error Tolerance = 0.01
         Maximum Absolute Pressure = 300 [Pa]
         Maximum Points = 100
         Maximum Temperature = 2500 [K]
         Minimum Absolute Pressure = 1 [Pa]
         Minimum Temperature = 300 [K]
         Pressure Extrapolation = No
         Temperature Extrapolation = Off
       END
       THERMAL CONDUCTIVITY:
         Option = Value
         Thermal Conductivity = CondQuartz
       END
       ABSORPTION COEFFICIENT:
         Absorption Coefficient = abscoeff
         Option = Value
       END
       SCATTERING COEFFICIENT:
         Option = Value
         Scattering Coefficient = 0. [m^-1]
       END
       REFRACTIVE INDEX:
         Option = Value
         Refractive Index = refrindex
       END
     END
   END

...

   DOMAIN: window
     Coord Frame = Coord 0
     Domain Type = Solid
     Location = B564,B565,B566,B567
     BOUNDARY: fluid window interface Side 2
       Boundary Type = INTERFACE
       Location = \
         F511.565,F512.566,F513.564,F587.566,F588.566,F593.564,F595.564,F598.5\
         65,F599.565,F600.567
       BOUNDARY CONDITIONS:
         HEAT TRANSFER:
           Option = Conservative Interface Flux
         END
         THERMAL RADIATION:
           Option = Conservative Interface Flux
         END
       END
     END
     BOUNDARY: shield window interface Side 2
       Boundary Type = INTERFACE
       Location = F585.566,F592.564,F596.565
       BOUNDARY CONDITIONS:
         HEAT TRANSFER:
           Option = Conservative Interface Flux
         END
         THERMAL RADIATION:
           Diffuse Fraction = 1.
           Emissivity = 0.2
           Option = Opaque
         END
       END
     END
     BOUNDARY: window bottom
       Boundary Type = WALL
       Location = F569.566,F572.565,F575.564
       BOUNDARY CONDITIONS:
         HEAT TRANSFER:
           Fixed Temperature = 300 [K]
           Option = Fixed Temperature
         END
         THERMAL RADIATION:
           Diffuse Fraction = 1.
           Emissivity = 1.
           Option = Opaque
         END
       END
     END
     BOUNDARY: window outside cyl
       Boundary Type = WALL
       Location = F576.564,F574.565,F571.566
       BOUNDARY CONDITIONS:
         HEAT TRANSFER:
           Heat Transfer Coefficient = 50 [W m^-2 K^-1]
           Option = Heat Transfer Coefficient
           Outside Temperature = 300 [K]
         END
         THERMAL RADIATION:
           Diffuse Fraction = 1.
           Emissivity = 1.
           Option = Opaque
         END
       END
       BOUNDARY SOURCE:
         SOURCES:
           EQUATION SOURCE: energy
             Flux = radiationloss*0.019-reradiationloss
             Option = Flux
           END
           RADIATION SOURCE: Radiation Source 1
             External Refractive Index = 1.0
             Option = Directional Radiation Flux
             Radiation Flux = radiationsource3z
             DIRECTION:
               Option = Normal to Boundary Condition
             END
           END
         END
       END
     END
     BOUNDARY: window outside spherical
       Boundary Type = WALL
       Location = F568.567,F570.566,F577.564,F573.565
       BOUNDARY CONDITIONS:
         HEAT TRANSFER:
           Heat Transfer Coefficient = 50 [W m^-2 K^-1]
           Option = Heat Transfer Coefficient
           Outside Temperature = 300 [K]
         END
         THERMAL RADIATION:
           Diffuse Fraction = 1.
           Emissivity = 1.
           Option = Opaque
         END
       END
       BOUNDARY SOURCE:
         SOURCES:
           EQUATION SOURCE: energy
             Flux = radiationloss*0.019-reradiationloss
             Option = Flux
           END
           RADIATION SOURCE: Radiation Source 1
             External Refractive Index = 1.0
             Option = Directional Radiation Flux
             Radiation Flux = radiationsource3r
             DIRECTION:
               Option = Normal to Boundary Condition
             END
           END
         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 with Value
           Temperature = 370 [K]
         END
       END
     END
     SOLID DEFINITION: Solid 1
       Material = QUARTZ
       Option = Material Library
       MORPHOLOGY:
         Option = Continuous Solid
       END
     END
     SOLID MODELS:
       HEAT TRANSFER MODEL:
         Option = Thermal Energy
       END
       THERMAL RADIATION MODEL:
         Number of Histories = 10000000
         Option = Monte Carlo
         Radiation Transfer Mode = Participating Media
         SCATTERING MODEL:
           Option = None
         END
         SPECTRAL MODEL:
           Option = Multiband
           SPECTRAL BAND: Spectral Band 1
             Frequency Lower Limit = freqlow
             Frequency Upper Limit = freqmid
             Option = Frequency
           END
           SPECTRAL BAND: Spectral Band 2
             Frequency Lower Limit = freqmid
             Frequency Upper Limit = freqhigh
             Option = Frequency
           END
         END
       END
     END

Opaque · June 14, 2014, 11:03

Would mind posting the section for the thermal radiation model details on the other side of the solid interface ?

I assume you are also using two spectral bands on the neighboring domains, correct ?

silvan · June 14, 2014, 11:37

Thanks for your quick reply!
Here is some more of the CCL code. It is about the fluid domain adjacent to the window domain (which has been posted above).
Please let me know whether this is sufficient info. Thank you!

Yes, I am using two bands in this domain as well.

Code:

   
   DOMAIN: fluid
     Coord Frame = Coord 0
     Domain Type = Fluid
     Location = B1045,B578,B781,B782
     BOUNDARY: crucible rxn interface Side 1
       Boundary Type = INTERFACE
       Location = F661.781
       BOUNDARY CONDITIONS:
         HEAT TRANSFER:
           Option = Conservative Interface Flux
         END
         MASS AND MOMENTUM:
           Option = No Slip Wall
         END
         THERMAL RADIATION:
           Diffuse Fraction = 1.
           Emissivity = 0.85
           Option = Opaque
         END
       END
     END
     BOUNDARY: fluid container interface Side 1
       Boundary Type = INTERFACE
       Location = F520.781,F521.781,...
       BOUNDARY CONDITIONS:
         HEAT TRANSFER:
           Option = Conservative Interface Flux
         END
         MASS AND MOMENTUM:
           Option = No Slip Wall
         END
         THERMAL RADIATION:
           Diffuse Fraction = 1.
           Emissivity = 0.2
           Option = Opaque
         END
       END
     END
     BOUNDARY: fluid crucible cover interface Side 1
       Boundary Type = INTERFACE
       Location = F615.781,F616.781,...
         END
         MASS AND MOMENTUM:
           Option = No Slip Wall
         END
         THERMAL RADIATION:
           Diffuse Fraction = 1.
           Emissivity = 0.85
           Option = Opaque
         END
       END
     END
     BOUNDARY: fluid crucible interface Side 1
       Boundary Type = INTERFACE
       Location = F525.781,F526.781,...
       BOUNDARY CONDITIONS:
         HEAT TRANSFER:
           Option = Conservative Interface Flux
         END
         MASS AND MOMENTUM:
           Option = No Slip Wall
         END
         THERMAL RADIATION:
           Diffuse Fraction = 1.
           Emissivity = 0.85
           Option = Opaque
         END
       END
     END
     BOUNDARY: fluid exit tube interface Side 1
       Boundary Type = INTERFACE
       Location = F515.781,F765.781
       BOUNDARY CONDITIONS:
         HEAT TRANSFER:
           Option = Conservative Interface Flux
         END
         MASS AND MOMENTUM:
           Option = No Slip Wall
         END
         THERMAL RADIATION:
           Diffuse Fraction = 1.
           Emissivity = 0.2
           Option = Opaque
         END
       END
     END
     BOUNDARY: fluid graphite wall interface Side 1
       Boundary Type = INTERFACE
       Location = F714.781,F715.781,...
       BOUNDARY CONDITIONS:
         HEAT TRANSFER:
           Option = Conservative Interface Flux
         END
         MASS AND MOMENTUM:
           Option = No Slip Wall
         END
         THERMAL RADIATION:
           Diffuse Fraction = 1.
           Emissivity = 0.85
           Option = Opaque
         END
       END
     END
     BOUNDARY: fluid inlet
       Boundary Type = INLET
       Location = F579.578
       BOUNDARY CONDITIONS:
         FLOW DIRECTION:
           Option = Normal to Boundary Condition
         END
         FLOW REGIME:
           Option = Subsonic
         END
         HEAT TRANSFER:
           Option = Static Temperature
           Static Temperature = 300 [K]
         END
         MASS AND MOMENTUM:
           Mass Flow Rate = 2.705e-5 [kg s^-1]
           Option = Mass Flow Rate
         END
         THERMAL RADIATION:
           Option = Local Temperature
         END
       END
     END
     BOUNDARY: fluid insulation interface Side 1
       Boundary Type = INTERFACE
       Location = F740.781,F741.781,...
       BOUNDARY CONDITIONS:
         HEAT TRANSFER:
           Option = Conservative Interface Flux
         END
         MASS AND MOMENTUM:
           Option = No Slip Wall
         END
         THERMAL RADIATION:
           Diffuse Fraction = 1.
           Emissivity = 0.7
           Option = Opaque
         END
       END
     END
     BOUNDARY: fluid outlet
       Boundary Type = OUTLET
       Location = F580.781
       BOUNDARY CONDITIONS:
         FLOW REGIME:
           Option = Subsonic
         END
         MASS AND MOMENTUM:
           Option = Average Static Pressure
           Pressure Profile Blend = 0.05
           Relative Pressure = 0 [Pa]
         END
         PRESSURE AVERAGING:
           Option = Average Over Whole Outlet
         END
         THERMAL RADIATION:
           Option = Local Temperature
         END
       END
     END
     BOUNDARY: fluid shield interface Side 1
       Boundary Type = INTERFACE
       Location = F602.782,F603.578,...
       BOUNDARY CONDITIONS:
         HEAT TRANSFER:
           Option = Conservative Interface Flux
         END
         MASS AND MOMENTUM:
           Option = No Slip Wall
         END
         THERMAL RADIATION:
           Diffuse Fraction = 1.
           Emissivity = 0.2
           Option = Opaque
         END
       END
     END
     BOUNDARY: fluid window interface Side 1
       Boundary Type = INTERFACE
       Location = F511.782,F512.782,...
           Option = Conservative Interface Flux
         END
         MASS AND MOMENTUM:
           Option = No Slip Wall
         END
         THERMAL RADIATION:
           Option = Conservative Interface Flux
         END
       END
     END
     DOMAIN MODELS:
       BUOYANCY MODEL:
         Buoyancy Reference Density = 1.784 [kg m^-3]
         Gravity X Component = 0 [m s^-2]
         Gravity Y Component = 0 [m s^-2]
         Gravity Z Component = -g
         Option = Buoyant
         BUOYANCY REFERENCE LOCATION:
           Option = Automatic
         END
       END
       DOMAIN MOTION:
         Option = Stationary
       END
       MESH DEFORMATION:
         Option = None
       END
       REFERENCE PRESSURE:
         Reference Pressure = 40 [Pa]
       END
     END
     FLUID DEFINITION: Fluid 1
       Material = Ar
       Option = Material Library
       MORPHOLOGY:
         Option = Continuous Fluid
       END
     END
     FLUID MODELS:
       COMBUSTION MODEL:
         Option = None
       END
       HEAT TRANSFER MODEL:
         Option = Thermal Energy
       END
       THERMAL RADIATION MODEL:
         Number of Histories = 10000000
         Option = Monte Carlo
         Radiation Transfer Mode = Surface to Surface
         SCATTERING MODEL:
           Option = None
         END
         SPECTRAL MODEL:
           Option = Multiband
           SPECTRAL BAND: Spectral Band 1
             Frequency Lower Limit = freqlow
             Frequency Upper Limit = freqmid
             Option = Frequency
           END
           SPECTRAL BAND: Spectral Band 2
             Frequency Lower Limit = freqmid
             Frequency Upper Limit = freqhigh
             Option = Frequency
           END
         END
       END
       TURBULENCE MODEL:
         Option = Laminar
       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 with Value
           Temperature = 1100 [K]
         END
       END
     END
   END

silvan · June 16, 2014, 09:49

Does anybody have an idea what I could have done wrong?
Any input is appreciated.

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June 14, 2014, 11:03		#2
Opaque Senior Member Join Date: Jun 2009 Posts: 1,804 Rep Power: 32	Would mind posting the section for the thermal radiation model details on the other side of the solid interface ? I assume you are also using two spectral bands on the neighboring domains, correct ?

June 16, 2014, 09:49		#4
silvan New Member Silvan Join Date: Jun 2014 Posts: 12 Rep Power: 11	Does anybody have an idea what I could have done wrong? Any input is appreciated.