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Code Manual for CONTAIN 2.0 - Federation of American Scientists

Code Manual for CONTAIN 2.0 - Federation of American Scientists

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whose default value is 0.32, p~jis the density <strong>of</strong> gas in the cell, pOis the pressure corrected density<br />

<strong>of</strong> gas from the upstream cell, Pi is the pressure in cell i, and Puis the pressure in the upstream cell.<br />

By default the flow path area,&, is the area <strong>of</strong> the dominant flow path as defined in the flow input.<br />

This area can be user-specified using the ADFLOW keyword; however, if this is done, it maybe<br />

desirable <strong>for</strong> the user to speci~ the dominant flow path explicitly using either FROMCELL or<br />

FROMVENT keywords. This is suggested because the flow path area will not change if ADFLOW<br />

is specified, while the dominant flow path may change if it is not also explicitly specified.<br />

Specifying the dominant flow path explicitly will prevent an inconsistent area from being used.<br />

There may be valid reasons <strong>for</strong> not following this suggestion; there<strong>for</strong>e, it is not en<strong>for</strong>ced by the<br />

code.<br />

The velocity <strong>of</strong> gas after it enters a cell is assumed to be constant at v~,i~until it ‘travels the cut<strong>of</strong>f<br />

distance XC.Beyond the cut<strong>of</strong>f distance it is assumed that the velocity declines linearly as gases are<br />

entrained into the flow stream. The gas velocity at the first impact, v~,l,is given by the maximum<br />

<strong>of</strong> the jet velocity and a <strong>for</strong>ced convective velocity<br />

‘gl=m=[vlvgintin[l:ll<br />

(6-101)<br />

where VIis the <strong>for</strong>ced convective velocity <strong>for</strong> the inner face <strong>of</strong> the first heat transfer structure in the<br />

cell (see Section 10.1.1.6). None <strong>of</strong> the parameters in the DCH-CELL block have an effect on v,.<br />

Because <strong>of</strong> this scheme, it is recommended that at least two structures be defined in subcompartments<br />

so that a <strong>for</strong>ced convection velocity will be calculated and stored in VI(and V2used under Case<br />

2 in the following section) <strong>for</strong> use in the TOF/KU model. If no structures are defined, then the<br />

model will use the average gas velocity through the cell, v~,.,~,in place <strong>of</strong> VI in the above<br />

expressions.<br />

The Kutateladze criterion can be evaluated using one <strong>of</strong> two options. Jn the default RHODG = GAS<br />

option orIIy the gas momentum is included in the numerator. If the RHODG = MIX option is<br />

invoked then debris momentum will be included in the numerator <strong>of</strong> NKU. Under the default<br />

RHODG = GAS option, N~u<strong>for</strong> the first impact, N~u,,,l,is given by<br />

N=<br />

‘u’s” /Fi=GE<br />

Pg,l %<br />

(6-102)

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