Environmental Engineering Reference
In-Depth Information
As a switch, the variable gflowp_dot is introduced. The streamslice command
delivers flowpaths for the given mesh and velocity field similar to the streamline
command. The information is gathered in two data structures. The structure verts
contains coordinates for all streamlines. If averts is not returned, arrows indicate
the direction along the flowpaths instead of dots. gflowp_dot has the additional
function to determine the streamline density: a doubled value produces approxi-
mately twice as much streamlines. interpstreamspeed evaluates the speed along
the streamlines, which is scaled by the sc parameter. sc is the inverse of the mean
velocity, multiplied by 10. mean initiates the calculation of the mean value and has
to applied twice, as we have arrays of dimension 2. Some manual adjustment is
surely necessary here: the author found it often appropriate to use the mean velocity
multiplied by a factor of 10. The last two commands have already been explained:
streamlines are finally plotted in yellow colour, using dots as time markers.
The result for a well with pumping rate Q ¼
10 4 m 3 /s is depicted in Fig. 14.6 .
2
10 4 m 3 /s.
The pumping rate is 2
Exercise 14.2. Confirm the following formulae for a control sample by choosing
an appropriate graphical output!
1. The distance between the well location and the stagnation point downstream
from the well is given by:
Q
d ¼
(14.17)
2
pQ x 0
100
5.4
80
5.3
60
5.2
40
5.1
20
5
0
4.9
-20
4.8
-40
4.7
-60
-80
4.6
-100
0
50
100
150
200
Fig. 14.6 Flow towards a well, depicted by filled head contours and flowpaths with speed dots
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