|
[Sponsors] |
Radiation in semi-transparent media with surface-to-surface model? |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
June 2, 2015, 10:49 |
Radiation in semi-transparent media with surface-to-surface model?
|
#1 |
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 |
|
June 2, 2015, 21:28 |
|
#2 |
Senior Member
Join Date: Jun 2009
Posts: 1,862
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. |
|
June 3, 2015, 12:01 |
|
#3 |
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 |
|
June 3, 2015, 13:49 |
|
#4 |
Senior Member
Join Date: Jun 2009
Posts: 1,862
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. |
|
June 4, 2015, 04:34 |
|
#5 |
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 06:25. |
|
June 4, 2015, 10:24 |
|
#6 |
Senior Member
Join Date: Jun 2009
Posts: 1,862
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. |
|
June 8, 2015, 11:33 |
|
#7 |
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? |
|
June 8, 2015, 12:17 |
|
#8 |
Senior Member
Join Date: Jun 2009
Posts: 1,862
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 ? |
|
June 10, 2015, 12:07 |
|
#9 |
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 |
|
June 10, 2015, 13:52 |
|
#10 |
Senior Member
Join Date: Jun 2009
Posts: 1,862
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, |
|
June 16, 2015, 15:48 |
|
#11 |
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 |
|
August 22, 2019, 07:30 |
|
#12 | |
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 |
||
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Porous media and surface model | MMatt | STAR-CCM+ | 4 | June 13, 2013 10:04 |
DO Model giving wrong results for optically thick media ? | pprllo | FLUENT | 3 | April 16, 2013 21:27 |
free surface model | sjtusyc | CFX | 3 | September 5, 2012 18:33 |
Internal CFD on a surface model (SW2010) | sw1990 | Main CFD Forum | 7 | January 4, 2011 19:36 |
Surface incident radiation | Pipiola | FLUENT | 0 | August 11, 2009 15:46 |