# TUI refractive-band

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 April 22, 2020, 12:34 TUI refractive-band #1 New Member   Join Date: Apr 2020 Posts: 3 Rep Power: 5 Hello everyone, I am struggling with the discrete ordinate model in TUI. After succesfully loading a case and turning On the discrete ordinate model with 2 bands, I fail at defining a material refrative index. Here is the relevant part: Code: ```/define/materials/change-create/glass/ glass glass is a solid change Density? [no] no change Cp (Specific Heat)? [no] no change Thermal Conductivity? [no] no change Absorption Coefficient? [no] yes Absorption Coefficient methods: (constant piecewise-linear piecewise-polynomial polynomial gray-band user-defined-gray-band user-defined) new method [constant] gray-band band1 (1/m) [0] 0.1 band2 (1/m) [0] 0.8 change Scattering Coefficient? [no] yes Scattering Coefficient methods: (constant piecewise-linear piecewise-polynomial polynomial gray-band user-defined-gray-band user-defined) new method [constant] gray-band band1 (1/m) [0] 0. band2 (1/m) [0] 0. change Scattering Phase Function? [no] no change Refractive Index? [no] yes Refractive Index methods: (constant refractive-band) new method [constant] refractive-band no data required.``` As you can see I can define the absorption and scattering coefficients but for some reason not the refractive index. I am using Ansys Fluent 17.1 in 3D. Thanks in advance, Tony

 April 26, 2020, 17:59 Refractive Index #2 Senior Member     Vinerm Join Date: Jun 2009 Location: Nederland Posts: 2,946 Blog Entries: 1 Rep Power: 35 Try list-properties for glass and see what it shows for refractive-index. __________________ Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority.

April 27, 2020, 05:20
RE: Refractive Index
#3
New Member

Join Date: Apr 2020
Posts: 3
Rep Power: 5
Thank you for your interest in the question vinerm.

Quote:
 Originally Posted by vinerm Try list-properties for glass and see what it shows for refractive-index.
Before the command detailed in the first post (/define/materials/change-create/glass/ glass), I get

Code:
```property name                        units       method      value(s)
-----------------------------------  ----------  ----------  ---------------
...
Absorption Coefficient               1/m         constant    0
Scattering Coefficient               1/m         constant    0
Scattering Phase Function                        isotropic   #f
Refractive Index                                 constant    1```

And after the command, it is changed to

Code:
```property name                        units       method      value(s)
-----------------------------------  ----------  ----------  ---------------
...
Absorption Coefficient               1/m         gray-band   (0.1 0.8)
Scattering Coefficient               1/m         gray-band   (0 0)
Scattering Phase Function                        isotropic   #f
Refractive Index                                 refractive-band  #f```

 April 28, 2020, 12:42 Bug #4 Senior Member     Vinerm Join Date: Jun 2009 Location: Nederland Posts: 2,946 Blog Entries: 1 Rep Power: 35 Could be a bug in that version. It is showing unassigned (#f). One way out is to write a user-define material database after defining the coefficients for the bands using GUI. The user-defined database is written in Scheme language and you can open it in any text editor. Look for the values that you have defined. Now, anytime you want to change the values, delete the existing material, change the values in the Scheme file, and reload the Scheme File via User-Defined Database. You won't have to modify any of the properties using the commands that you are using. Modify all together within the Scheme file and just read it. __________________ Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority.

 April 28, 2020, 13:48 RE: Bug #5 New Member   Join Date: Apr 2020 Posts: 3 Rep Power: 5 All right, thanks for the tip

 Tags discrete ordinate model, non-gray, refractive index, tui