Re: Abridged summary of xbeach@googlegroups.com - 1 Message in 1 Topic
Jaap van Thiel de Vries
You can optimize your grid resolution depending on your wave boundary
conditions. Basically your grid resolution should be sufficiently high
to describe the long waves (12 points at least per wave length) in
your model domain. This means offshore your grid resolution can be
coarser than nearshore. Nearshore you can have a higher resolution
depending on the morphodynamic response you want to simulate.
On the Xbeach website we have just introduced a pre-release of a
matlab toolbox. The toolbox includes also scripts to set-up an XBeach
model. There is a specific script that computes a cross-shore grid
resolution based on your offshore wave boundary conditions
(xb_generate_xgrid). You can download the matlab toolbox at:
https://repos.deltares.nl/repos/OpenEarthTools/tags/xbeach_release_21Apr2011/
At https://public.deltares.nl/display/XBEACH/Toolbox you find an
overviewe of function collections and some examples on how to use the
toolbox to i.e setup a model or read xbeach output.
Goodluck!
Jaap.
On Wed, Apr 20, 2011 at 2:05 AM, <xbeach+...@googlegroups.com> wrote:
> Today's Topic Summary
>
> Group: http://groups.google.com/group/xbeach/topics
>
> computing time [1 Update]
>
> Topic: computing time
>
> victor quilfen <vqui...@gmail.com> Apr 19 12:51AM -0700 ^
>
> Hi everyone!
>
> I would like to know if there were any tricks to optimize the
> computing time on XBeach?
>
> I used the following (mesh may be too thin) : 350x350 with dx=dy=2.
> How do I choose my time more...
>
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Mo
the tools are excellent - I wasn't aware of them until you sent the
message. Thanks to anyone who contributed !
I re-made my grids and testing them now - I have a few questions that
I'd appreciate if you could answer:
Here is how I run the xb_generate_model.m
xb = xb_generate_model(...
'bathy', {'x', xsmalld,'y', ysmalld, 'z', bedsmall},...
'waves', {'Hm0',[2.9 2.9 3.0 3.3 3.5 3.6 3.4 3.1 3.0],'Tp',[15.2 14.5
13.5 12.0 10.8 10.4 10.5 10.5 10.7],'duration', [5400 5400 5400 5400
5400 5400 5400 5400 5400]},...
'tide',{'time', [0 5400 10800 16200 21600 27000 32400 37800 43200],
'front', [0 0 0.5 1.37 2.13 2.08 1.27 0.57 0]', 'back', [0 -0.25 -0.42
-1.03 -1.62 -1.27 -1.1 -1 -0.92]},...
'settings', {'tstop', 43200, 'tint', 120, 'gamma', 0.55, 'morfac',
5});
I prepared xsmalld ysmalld and bedsmall from my earlier grid files.
xsmalld = [0 19.9 .......2241] (1x251 vector)
ysmalld =[0 11.3 ...... 1007] (1x367 vector)
bedsmall is the matrix (367x251)
everything works and I get the output files created as expected - one
thing is that yori in the params.txt created is -52.6...
even though the y.grd created starts at zero - and I plot the grid
using the new x.grd y.grd bed.dep and it looks as expected. The new
grid is (226x537) bigger.
y.grd has 1049 as the last value (used to be 1007) - I understand the
change here, since I changed some of the default values in
xb_grid_ygrid - and I see that the z values are interpolated where
necessary - but I can't figure out why the yori is a negative value
now?? I guess I'll test it as yori=0 and yori=-52.6.. and see what
happens.
btw, alfa is 0 - and I turned off the rotation in the options.
Another question is about the tides,
normally I use two signals for the tide (the values as in
xb_generate.m above) one for the offshore boundary and the second is
for land side (I am working on barrier island breaching so I have an
open boundary at the back - so it is not really "land")
zs0file = tide.txt
tideloc = 2
these two are the same as I had before - but the paulrevere parameter
is not created - normally I use paulrevere = land (or paulrevere = 0
according the manual) and I know it is working fine like that.
but the following warning in the xb_generate_tide got me a little
confused:
"WARNING: to define two different timeseries on the lateral boundaries
% without specifying waterlevels at the back, set the
paulrevere
% option in your parameter setting to 1 and define the
lateral
% boundary conditions as if front and back in this
function."
Could you please explain this message ?
the reason I ask this, in my last run (which stalled after a while) I
saw flooding on my grid where the elevations are above zero (it is
basically the road in my grid, and water was coming in from the side
boundary?? before any overwash occurs at the front/back dunes) I built
a "wall" there to prevent it and I guess it will fix this as it did
before.
Sorry for the long email,
looking forward to meet you at the CS11! I am registered for the short
course as well :)
cheers
Onur
On Apr 23, 7:03 am, Jaap van Thiel de Vries
> Hi Victor,
>
> You can optimize your grid resolution depending on your wave boundary
> conditions. Basically your grid resolution should be sufficiently high
> to describe the long waves (12 points at least per wave length) in
> your model domain. This means offshore your grid resolution can be
> coarser than nearshore. Nearshore you can have a higher resolution
> depending on the morphodynamic response you want to simulate.
>
> On the Xbeach website we have just introduced a pre-release of a
> matlab toolbox. The toolbox includes also scripts to set-up an XBeach
> model. There is a specific script that computes a cross-shore grid
> resolution based on your offshore wave boundary conditions
> (xb_generate_xgrid). You can download the matlab toolbox at:
>
>
> Athttps://public.deltares.nl/display/XBEACH/Toolboxyou find an
> toolbox to i.e setup a model or read xbeach output.
>
> Goodluck!
>
> Jaap.
>
> On Wed, Apr 20, 2011 at 2:05 AM, <xbeach+...@googlegroups.com> wrote:
> > Today's Topic Summary
>
> > Group:http://groups.google.com/group/xbeach/topics
>
> > computing time [1 Update]
>
> > Topic: computing time
>
Mo
email.
in xb_finalise_grid, if I use the "lateral_extent" function creates
"n" number of new rows where the y value goes to negative, then the
returned xgrid ygrid zgrid is used in xb_generate_grid to calculate
% determine origin
xori = min(min(xgrid));
yori = min(min(ygrid));
xgrid = xgrid - xori;
ygrid = ygrid - yori;
here the yori is negative and is used to shift the ygrid so that it
will start at zero but then while creating the xb sturcture
xb = xb_empty();
xb = xb_set(xb, 'nx', nx, 'ny', ny, 'xori', xori, 'yori', yori, ...
'alfa', mod(360-alpha, 360), 'vardx', 1, 'posdwn', OPT.posdwn);
yori - is still the yori = min(min(ygrid)); which is negative and this
value is written to params.txt - I think since it is used to shift
ygrid to start at zero, yori should also be updated before written
into the xb structure thus the params.txt
something very small to note
:
in the description part of the xb_finalise_grid.m, we have:
% lateral_seawalls: close dry lateral
% boundaries with
% sandwalls
but the name of the private function is lateral_sandwalls.
Onur