The dose conservation criterion compares the quantity's local dose error
with its total dose in the computational domain. The total dose is
obtained from (3.6-13) where
is the concentration of
quantity
at grid point
and
is the cell area associated
with grid point
(see Figures 3.4-3 and 3.4-6).
We get the grid criterion (3.6-14) for a grid line at the
vertical position
by adding up the local dose error along this
grid line in lateral direction (see Figure 3.6-2).
In (3.6-14)
and
denote the number of grid lines in
vertical and lateral direction, respectively.
is the number of
different quantities which are resolved by the grid, and
is
accuracy parameter. An analogous expression is used as the criterion for a
grid line at a lateral position
.
The criterion is used to decide if grid lines have to be
inserted in the vicinity of vertical position
. If this grid line were
deleted, the dose error would be
(3.6-15). This
criterion is applied to decide if the grid line may be deleted.