Measuring radiant heat flux in the Z plane

[Matthew ..]

Hi All,

I was wondering if it is possible to measure incident radiant heat flux in the Z plane, e.g. with a slice file? The purpose of this would be to use it as amethod of determining when tenability is lost based on radiant heat flux. Some people currently judge this acceptance criteria based on the hot layer temperature (e.g. the temperature at the ceiling), but this does not seem very exact as there is often great variance in ceiling temperatures.

I have had a look through the guide and there does not seem to be a simple method. I have come up with a kind of convoluted method, but I think there must be an easier way. 

I have broken the domain into many smaller squares and then use a statistic to toggle a porous obstruction on when the radiant heat flux exceeds a certain level. I've only just tried this tonight and I'm testing it out, there may be some significant flaws.

&SURF ID='POROUS',
      POROUS=.TRUE./

&DEVC ID='Radiative Heat Flux Gas_MAX', QUANTITY='RADIATIVE HEAT FLUX GAS', STATISTICS='MAX', XB=0.0,2.0,0.0,2.0,2.1,2.1,SETPOINT=2.5/
&OBST  XB=0.0,2,0,2,2.1,2.1,COLOR='RED', SURF_ID='POROUS', DEVC_ID='Radiative Heat Flux Gas_MEAN',/

The DEVC and OBST lines are repeated to cover the whole domain.

Also, I have not defined an orientation for the quantity, will it default to integrating around the Z axis (noting that it is a plane)?

Thanks in advance!

Regards,

Matt

[Randy McDermott]

Why would you not just use a radiometer device as described in section 16.9.5 of the user guide?  You can put an array of such devices in whatever plane you want and extract fluxes for specific directions.

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[Matthew ..]

Hi Randy,

Thanks for the reply. That is what I have done in the past, however now I want to create a way to visualise the areas with radiative heat fluxes above a certain level in Smokeview. Can I do that with an array of radiometers?

My method is attempting to approximate a slice file, although I don't believe it is very elegant. The porous attribute will hopefully mean the obstructions don't interfere with the dynamics of the model.

Regards,

Matt

[Randy McDermott]

What is wrong with a SLCF of INTEGRATED INTENSITY?

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[Matthew ..]

Hi Randy,

I had to search for that in the user guide and technical guide - I haven't come across it before. There does not seem to be a lot of information on it, but based on your comment I will try it out!

Thanks!

Matt

[Randy McDermott]

It's in Table 16.12 of the user guide.  And discussed in Section 6.2 of the tech guide.

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