radiation setting, how?

alpharays786
alpharays786 Altair Community Member
edited October 2020 in Community Q&A

Hi,

 

In the solar radiation model mentioned that:

 

specular transmissivity + diffuse transmissivity + specular reflectivity + diffuse reflectivity + absorptivity = 1

 

The questions are:

 

1) In Acuconsole, absorptivity does not need to specify. So, is it means that it is automatically generated based on above equation?

E.g: 0.5+0+0.2+0+absorptivity=1

Is it means that absorptivity value automatically = 0.3??

 

2) Is it emissivity value must be equal to absorptivity value??

 

 

Thanks

Sorry for my english..

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Answers

  • ydigit
    ydigit
    Altair Employee
    edited May 2015

    1. Yes absorptivity is the rest of the equation, as you mentioned

    2. AcuSolve takes absoprtivity = emissivity and hence you once specify emissivity

  • alpharays786
    alpharays786 Altair Community Member
    edited May 2015
    Altair Forum User said:

    1. Yes absorptivity is the rest of the equation, as you mentioned

    2. AcuSolve takes absoprtivity = emissivity and hence you once specify emissivity

     

     

    Regarding question 2, if we setup specular transmissivity = 0.35, specular reflectivity = 0.05 and emissivity = 0.6

    what is value of absorptivity?

     

    Thanks 

  • alpharays786
    alpharays786 Altair Community Member
    edited May 2015

    Regarding question 2, if we setup specular transmissivity = 0.35, specular reflectivity = 0.05 and emissivity = 0.6

    what is value of absorptivity?

     

    Thanks 

  • ydigit
    ydigit
    Altair Employee
    edited May 2015

    For solar radiation model, absorptivity would be calculated from the rest of the equation

    i.e. 1- Transsivities - reflectivities  (page 63 of Command reference manual)

     

    For enclosure radiation mode, absorptivity would be equal to emissivity. (Kirchhoff Law and gray surface assumption, Pg 56 CRM)

     


     

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