This example describes the nesting of the Siu Lam model in the Pearl Estuary model. The grid layout of both models is given in the Figure below:
erview grids overall and nested models
The input and output files of this example are stored in the FLOW Tutorial directory: <tutorial\flow\nesthd>.
Using NESTHD1 the monitoring stations file and the administration file are generated. The contents of these files are shown below:
Part of monitoring stations file <nesthd1.obs>:
(M,N) = ( 27, 35) 27
35
(M,N) = ( 27, 36) 27
36
(M,N) = ( 27, 41) 27
41
(M,N) = ( 27, 42) 27
42
(M,N) = ( 28, 35) 28
35
(M,N) = ( 28, 36) 28
36
.
. . . .
.
. . . .
(M,N) = ( 29, 35) 29
35
(M,N) = ( 29, 36) 29
36
(M,N) = ( 29, 41) 29 41
(M,N) = ( 29, 42) 29
42
(M,N) = ( 31, 30) 31
30
(M,N) = ( 31, 31) 31 31
These monitoring stations have been
included (added) to the already existing <*.obs>
file of the
Part of the administration file <nesthd1.adm>:
*
*
WL |
*
*
Run date :2005/05/11 22:36:06
*
*
Name grid file overall model
: overall.grd
*
Name enclosure file overall model
: overall.enc
*
*
Name grid file detailed model
: nested.grd
*
Name enclosure file detailed model
: nested.enc
*
Name bnd. definition file
detailed model : nested.bnd
*
*
Name nest administration file
: nesthd1.adm
*
Name FLOW observation file
: nesthd1.obs
Nest
administration for water level support point (M,N) = (
49, 1)
28
45 0.5107
29
45 0.1822
28
46 0.2264
29
46 0.0808
Nest
administration for water level support point (M,N) = (
56, 1)
28
43 0.1496
29
43 0.0271
28
44 0.6972
29
44 0.1261
.
. . .
.
. . .
Nest
administration for water level support point (M,N) = (
53, 74)
47
45 0.8564
48
45 0.1436
0
0 0.0000
0
0 0.0000
Nest
administration for water level support point (M,N) = (
57, 74)
47
44 0.3268
48
44 0.0965
47
45 0.4453
48
45 0.1315
Nest
administration for velocity support
point (M,N) = ( 49,
1) Angle = 20.409
28
45 0.3888
29
45 0.3216
28
46 0.1585
29
46 0.1311
Nest
administration for velocity support
point (M,N) = ( 56,
1) Angle = 20.409
28
43 0.1368
29
43 0.0773
28
44 0.5022
29
44 0.2838
.
. . .
.
. . .
Nest
administration for velocity support
point (M,N) = ( 53, 74) Angle = 122.632
47
45 0.9973
48
45 0.0027
0
0 0.0000
0
0 0.0000
Nest
administration for velocity support
point (M,N) = ( 57, 74) Angle = 122.632
47
44 0.4247
48
44 0.0355
47
45 0.4982
48
45 0.0416
Remarks:
· When you run the NESTHD1 tool, the location of the nested boundary should be final.
· The type of data (water level or velocity) need not be final. That’s why NESTHD1 generates the administration for both.
· The type of data should also be final. NESTHD1 only generates the administration for time-series.
The first lines, starting with an asterisk, are comment lines. These are followed by several blocks of 5 lines containing the information on nesting of water level and transport boundaries. The first of these lines gives the indices of the boundary support point. This line is followed by 4 lines containing the indices of the surrounding overall model monitoring stations and the relative weights of these stations. The information on nesting of water levels and transport is followed by information on nesting of velocities.
To adjust the nesting, for instance to avoid the use of a monitoring station that dries during the computation, the administration file should be adjusted by hand.
Before running NESTHD2, first the overall model should be run, using the <o2d.mdf> file.
Remark:
· It is a good modelling practice to re-generate the bathymetry in the overall model using the detailed bathymetry of the nested model.
If you Verify this scenario the following warning will be generated:
***
WARNING Station (M,N) = ( 28, 46) lies outside the
computational domain
This means that this required nesting stations lies on a dry point. If you check the administration file, you will see that every boundary support point has at least 2 overall nest stations. Ignoring the nest station which lies on a dry point would result in the worst case that the nesting information only comes from 1 overall station. (If you check the administration file carefully, you will find out that the mentioned station is always part of a set of 4.)
Using the administration file <nesthd1.adm> and the history file <trih-o2d.*> of the Pearl Estuary model, the boundary conditions for the Siu Lam model have been generated by running NESTHD2.
The result files are the hydrodynamic flow boundary conditions <siulam2d.bct> and the transport boundary conditions <siulam2d.bcc>.
The diagnostic file contains the following warning:
*** Warning: Nest station (
28, 46) not on history file. Weights reset
This station, as noted before, lies on a dry point. NESTHD2 then resets weights.