PAT312, Section 68, December 2006 S68-1 Copyright 2007 MSC.Software Corporation SECTION 68 PARTICIPATING MEDIA AND AMBIENT NODE

PAT312, Section 68, December 2006 S68-2 Copyright 2007 MSC.Software Corporation

PAT312, Section 68, December 2006 S68-3 Copyright 2007 MSC.Software Corporation PARTICIPATING MEDIA Participating media KFLAG = 0: Transmissivity evaluated directly Transmissivity (tau) is 1.0 in a vacuum Valid values from 0 to 1.0 KFLAG = 1 Beers Law Transmissivity evaluated as extinction coefficient Tau = EXP ( - extinction coefficient * distance) KFLAG is set in the VFAC template

PAT312, Section 68, December 2006 S68-4 Copyright 2007 MSC.Software Corporation PARTICIPATING MEDIA (Cont.) Transmissivity or Extinction Factor can vary: Time dependent via MPID Temperature dependent via MPID Wavelength dependent Data entered in VFAC template

PAT312, Section 68, December 2006 S68-5 Copyright 2007 MSC.Software Corporation ASSUMPTIONS FOR THE PARTICIPATING MEDIA MODEL IN MSC.THERMAL The assumptions made for the participating media model in MSC.Thermal are The media is isothermal The media is in equilibrium with its internal energy The media extinction coefficient is not a function of position The optical thickness is small enough that the linear approximation of the exponential function is reasonable and the media is only weakly interacting with itself

PAT312, Section 68, December 2006 S68-6 Copyright 2007 MSC.Software Corporation NETWORK WITHOUT PARTICIPATING MEDIA

PAT312, Section 68, December 2006 S68-7 Copyright 2007 MSC.Software Corporation NETWORK WITH PARTICIPATING MEDIA

PAT312, Section 68, December 2006 S68-8 Copyright 2007 MSC.Software Corporation A SIMPLE RESISTOR NETWORK FOR AN ENCLOSURE WITH PARTICIPATING MEDIA AND AN AMBIENT NODE