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

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

VELEVF<br />

= velevf<br />

a pool path. The maximum elevation allowed <strong>for</strong> a pool path end is the<br />

elevation <strong>of</strong> the top <strong>of</strong> the cell, and the minimum elevation allowed <strong>for</strong> a gas<br />

path end is the elevation <strong>of</strong> the bottom <strong>of</strong> the cell. The user should consider<br />

the pool-gas hierarchy discussed in Section 4.2 and the gravitational head<br />

<strong>for</strong>mulation discussed in Section 4.4.5 prior to specifying this elevation and<br />

in particular should note that a flow path connected to the top <strong>of</strong> a cell is<br />

treated differently from side-connected or bottom-connected paths. In<br />

general, the robustness <strong>of</strong> the code will be improved if the gas head space<br />

associated with the onset <strong>of</strong> gas or pool flow in a side-connected path is fairly<br />

substantial (on the order <strong>of</strong> 20?10<strong>of</strong> the cell volume). Side-connected paths<br />

attached very close to the top <strong>of</strong> the cell are not recommended. To avoid<br />

accidental specification <strong>of</strong> such a side connection when a top connection is<br />

intended, it is recommended that the user rely on the CELLHIST input in the<br />

cell GEOMETRY block to speci~ cell elevations directly, rather than rely on<br />

values that would otherwise be calculated by the code from the initial cell gas<br />

center-<strong>of</strong>-volume elevation, the cell gas “height,” and the initial gas and pool<br />

volumes. (m)<br />

the absolute elevation <strong>of</strong> the front (TO) end <strong>of</strong> an engineered vent. The<br />

default value <strong>of</strong> “velevf” is the top <strong>of</strong> the cell to which the end is attached ~<br />

as shown in Figure 4-4) <strong>for</strong> a gas path and the bottom <strong>of</strong> the cell (H~,i)<strong>for</strong> a<br />

pool path. The considerations involved in choosing “velevf” are similar to<br />

those <strong>for</strong> “velevb,” which is discussed above. (m)<br />

The user may introduce a number <strong>of</strong> different global table options in which the area or user-specified<br />

flow rate is specified as a function <strong>of</strong> time or pressure difference. The type <strong>of</strong> table is specified<br />

through a keyword picked from the list below and then followed by standard table keywords FLAG,<br />

X, and Y as indicated in the ENGVENT input template. (These keywords are also discussed in<br />

Section 14.4.2.) If any tables described below are used in the input, the user should take them into<br />

account in setting the number <strong>of</strong> global tables “numtbg” and maximum global table size “maxtbg”<br />

in the global CONTROL block.<br />

AREA-T the keyword <strong>for</strong> initiating the specification <strong>of</strong> a table <strong>for</strong> area versus time.<br />

IRAREA-P the keyword <strong>for</strong> initiating the specification <strong>of</strong> a table <strong>for</strong> area versus pressure<br />

difference. The mea is treated as irreversible in this option. The table value<br />

will be used only if it is larger than the existing area. Note that the area is<br />

initialized at the value specified through the VAREA keyword, if specified;<br />

otherwise, it is initialized to zero.<br />

MFLOW-T the keyword <strong>for</strong> initiating the specification <strong>of</strong> a table <strong>for</strong> mass flow versus<br />

time. Note that the energy transfer associated with the flow is calculated the<br />

same way as that <strong>for</strong> pressure-driven flow. There<strong>for</strong>e, violations <strong>of</strong> the<br />

second law <strong>of</strong> thermodynamics will occur if the flow opposes the pressure<br />

drop across the flow path.<br />

Rev O 14-29 6/30/97

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

Saved successfully!

Ooh no, something went wrong!