ERDC/CHL CHETN-IV-32
June 2001
boundary nodes are modified. Therefore, normal flows on internal-barrier boundaries exactly
match the value computed by summing the Bernoulli-based pipe flow added to the broad-crested
weir formula flow in the limit as grid size becomes small. The procedure allows for free
tangential slip.
MODIFIED INPUT REQUIREMENTS FOR ADCIRC VERSION 40.02 AND HIGHER: In
order to specify a leaky internal-barrier boundary, the following boundary information must be
specified in the unit 14 (grid) input file.
Leaky internal-barrier flow boundary segments are input as normal flow (or discharge) boundary
segments with boundary type, IBTYPE, designated equal to either 5 or 25 depending on the
exact treatment desired for the leaky internal-barrier boundaries. Each leaky internal boundary is
input as a normal-flow boundary segment. The following information is provided for each leaky
internal-barrier boundary segment:
NVELL(K), IBTYPE: For each leaky internal-barrier boundary segment; these values are
directly followed by the boundary-node pairs within the segment and other information
for the leaky-barrier boundary-node pairs.
NVELL(K) = The number of leaky internal-boundary node pairs on a particular
segment.
IBTYPE = 5: Essential leaky internal-barrier normal-flow boundary with free
tangential slip allowed. The leaky internal (island type) barrier boundary
allows free surface subcritical and supercritical normal cross-barrier
inflow and outflow once the barrier has been overtopped. Cross-barrier
pipes are located under the top of the barrier which allow free discharging,
full-pipe cross-barrier inflow/outflow and submerged discharging, full-
pipe cross-barrier inflow/outflow once water level rises above the crown
of the pipe on at least one side of the barrier. The computed cross-barrier
flow is treated as an essential boundary condition. Tangential slip is
allowed. This boundary condition applies to weir-type barriers that have
cross-barrier pipes. The barrier lies entirely within the computational
domain. Normal-flow computations for the weir and pipe component
flows are based on water elevations on both sides of the barrier.
IBTYPE = 25: Natural leaky internal-barrier normal-flow boundary with free
tangential slip allowed. The leaky internal (island type) barrier boundary
allows free surface subcritical and supercritical normal cross-barrier
inflow and outflow once the barrier has been overtopped. Cross-barrier
pipes are located under the top of the barrier that allow free discharging,
full-pipe cross-barrier inflow/outflow and submerged discharging, full-
pipe cross-barrier inflow/outflow once water level rises above the crown
of the pipe on at least one side of the barrier. The computed cross-barrier
flow is treated as a natural boundary condition. Tangential slip is allowed.
This boundary condition applies to weir-type barriers that have
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