10.08.2013 Views

Code Manual for CONTAIN 2.0 - Federation of American Scientists

Code Manual for CONTAIN 2.0 - Federation of American Scientists

Code Manual for CONTAIN 2.0 - Federation of American Scientists

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

If slip is ignored completely, then Vmis given by<br />

v= =‘m ( ‘gti’ ‘d2,avg )<br />

(6-1 14)<br />

If N~u,,,2> Nfi,TJ,then debris is assumed to remain airborne until it traps by gravity or flows out <strong>of</strong><br />

the cell. The trapping rate will be calculated as described below.<br />

6.3.6.3 TOF/KU Case 3: No Tramirw From First or Second Kutateladze Number Criterion. This<br />

section describes the case where the inflow velocity and other conditions are such that neither <strong>of</strong> the<br />

two N~Ure-entrainment criteria are met. There<strong>for</strong>e, debris will either gravitationally settle to<br />

horizontal surfaces or flow out <strong>of</strong> the cell. The user has some control over this by specifying the<br />

third trapping length, L,, and how the debris velocity is treated with the VNOST = GFT and VNOST<br />

= CNVEL options. Some guidance on the selection <strong>of</strong> L, and the VNOST option is provided in the<br />

following section.<br />

The trapping rate <strong>for</strong> this case is given by<br />

(6-115)<br />

where t,,~is the characteristic residence time <strong>for</strong> debris that is not trapped under the first two deentrainment<br />

criteria. In the VNOST = CNVEL option (the default), the debris in the cell is assumed<br />

to travel at the average debris outlet velocity; there<strong>for</strong>e, t,,qis given by<br />

L3<br />

t =— (6-1 16)<br />

S,3<br />

‘d,out<br />

where &is a user-specified distance <strong>for</strong> this case. Four reasonable choices <strong>for</strong> this distance are(1)<br />

the G17Theight, L@,(2) the cell height, (3) 6 times the cell volume divided by total SUfiaCearea m<br />

was also suggested <strong>for</strong> ~, and (4) a large value to approximate infinity. The fourth choice causes<br />

debris to remain airborne until it is swept out <strong>of</strong> the cell by flow. Under this approach the VNOST<br />

option has no effect. The recommended approach is to use the first choice, which is the default.<br />

If the VNOST = GIW option is invoked, t,,~is given by<br />

L~<br />

t ‘—<br />

S,3<br />

Vgft<br />

(6-117)<br />

Under this option the debris that is not trapped according to the two calculated N~unumbers is<br />

assumed to gravitationally settle to horizontal surfaces. The most logical selection <strong>of</strong> ~ <strong>for</strong> this<br />

option is the cell height. By default ~ will be set equal to the “lengft” value, which will be set equal

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!