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Code Manual for CONTAIN 2.0 - Federation of American Scientists

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Note that the default correlations will not be considered at all if one or more <strong>of</strong> the user-defined<br />

correlations has been invoked. If it is desired to have the code choose between a default correlation<br />

and a user-defined correlation, then the default correlation must also be entered explicitly as one <strong>of</strong><br />

the user-defined correlations.<br />

10.1.3.3 User-Defined Forced Convection Correlations. Options permitting the user to specify<br />

<strong>for</strong>ced convection correlations have also been provided. These options are virtually identical to the<br />

natural convection options except that N~, is replaced by the Reynolds number N~.:<br />

(10-29)<br />

The user specifies the quantities %, .... d~,ad,.... dd. If one <strong>of</strong> the correlations is specified, but not<br />

both, the <strong>for</strong>ced convection Nusselt number, N~u,f,is equated to whichever correlation is specified;<br />

as with the natural convection correlations, the default <strong>for</strong>ced convection correlation is not<br />

considered if one or more <strong>of</strong> the user-defined <strong>for</strong>ced convection correlations is invoked. If both <strong>of</strong><br />

the correlations are invoked, the following options are available:<br />

1.<br />

2.<br />

3.<br />

N Nu,f N ). This is the default option.<br />

= m@NNu,f,l > Nu,f,2<br />

If the keyword STBFCOR is specified, NNUf= N Nu,f,lwhen the boundq layer density gradient<br />

is stabilizing, and NNu,f= NNUf,2when the density gradient is destabilizing. Physically, the ~<br />

motivation <strong>for</strong> defining this option may be less clear than in the case <strong>of</strong> natural convection, but<br />

it may prove usefi31in some instances. If STBFCOR is specified <strong>for</strong> a wall, the stability<br />

criterion is applied as if it were a floor.<br />

A root-sum-power combination <strong>of</strong> the two correlations can be used:<br />

NNu,f = NN~~,l+NN~f,21’m2<br />

( )<br />

The value <strong>of</strong> the exponent mz is specified through the “xm2” variable.<br />

(10-30)<br />

If <strong>for</strong>ced convection in<strong>for</strong>mation has been specified through one <strong>of</strong> the tabular options and NNufitself<br />

has not been specified directly in the table, the resulting Reynolds numbers will be used in the above<br />

user-defined <strong>for</strong>ced convection correlations. However, if NNufhas been specified directly, any <strong>of</strong> the<br />

above user-defined <strong>for</strong>ced convection correlations will be superseded by the tabular values.<br />

10.1.3.4 Mixed Convection. The effects <strong>of</strong> mixed natural and <strong>for</strong>ced convection depend in part on<br />

whether the buoyancy <strong>for</strong>ces are in the same direction as the <strong>for</strong>ced flow (assisted convection) or in<br />

the opposite direction (opposed convection). For assisted laminar convection, a relation that has<br />

some theoretical and experimental support is<br />

Rev. O 10-20 6/30/97

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