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GETVAR Error in Multiband Monte Carlo Radiation Simulation with Directional Source 

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June 14, 2014, 03:45 
GETVAR Error in Multiband Monte Carlo Radiation Simulation with Directional Source

#1 
New Member
Silvan
Join Date: Jun 2014
Posts: 8
Rep Power: 3 
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 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*0.019reradiationloss 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*0.019reradiationloss 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 

June 14, 2014, 11:03 

#2 
Senior Member
Join Date: Jun 2009
Posts: 296
Rep Power: 9 
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 14, 2014, 11:37 

#3 
New Member
Silvan
Join Date: Jun 2014
Posts: 8
Rep Power: 3 
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 = 2.705e5 [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 

June 16, 2014, 09:49 

#4 
New Member
Silvan
Join Date: Jun 2014
Posts: 8
Rep Power: 3 
Does anybody have an idea what I could have done wrong?
Any input is appreciated. 

Tags 
error, getvar, monte carlo, multiband, source 
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