brezo-visit user instructions

BREZO-VisIT Integration – Basic User Instructions

1

BREZO-VisIT: BASIC USER INSTRUCTIONS

I. Download and Install the VisIT Visualisation Tool.

The Latest version of VisIT can be obtained from the LLNL website, at:

https://wci.llnl.gov/codes/visit/1.10.0/visit1.10.0.exe

Note:, During installation, the default database plugin may be set to “VTK” (which is the format in

which BREZO writes data for visit). See Figure 1 below.

Figure 1: Setting Default database reader plugin to VTK

https://wci.llnl.gov/codes/visit/1.10.0/visit1.10.0.exe


2

II. Configure BREZO to Output VisIT Animation Files

Using Line 10 of the BREZO model’s “*.input” file, configure BREZO to output VisIT animation files.

For Example, in the sample configuration below:

Line 10: anim_onoff, anim_ntrvl, anim_start, anim_units 4 10000 1 0

The value of first variable anim_onoff=4 defines whether animation output files will be created and

in what output file format these will be. In this case, the “4” instructs BREZO to output animations to

be visualised with VisIT. The eight possible values for this variable correspond to the following

animation output configurations (Select as appropriate):

0=off (No animation)

1=Tecplot

2=Matlab

3=tecplot & Matlab

4=VisIT

5=Visit & Tecplot

6=Visit & Matlab

7=All

For the model defined by this input file, BREZO will now output animation database files in VisIT’s

“*.vtk” format. The resulting animation database is composed of a series of “*.vtk” files, each

containing animation data for a single time step. The seven digit number added to each file name

indicates the simulation cycle data that has been written into the file. E.g: The file name

“newark_BH.1.0065000.vtk” indicates that this file contains the animation data for the 65000th cycle

of the Newark_BH.1 simulation.

Note: As you might have already noticed, the seven digits before the file extension imply that the

maximum cycle BREZO can animate with the VisIT option (without a restart) is the 9,999,999th cycle.

This should be sufficient for many practical purposes, however should additional animation cycles be

required beyond this, at this time it is advisable that the simulation be split into a number of parts,

each with a maximum animation time step of no more than 9,999,999.


3

III. Loading VTK Files into VisIT

After starting the BREZO simulation, BREZO immediately begins to write out “.vtk” files at the

defined interval of cycles. The files are written progressively as BREZO computes the solutions for

each time step and this allows the VisIT user to monitor the simulation in real time if this is desired.

To load the simulation data into VisIT, first start the VisIT application and then from the main menu,

select: File > Select File (see Figure 2 below)

Figure 2: Loading Files into VisIT

This will bring up the File Selection Window as shown below. Remove any preselected files by

clicking remove all, then browse to the directory (File Path) with your simulation files. Make sure the

file grouping option is set to “smart”, this will ensure that all files related to a given simulation are

automatically grouped together and loaded as a single simulation database, instead of having the

user manually load each file of the simulation database. Select the relevant database, then click ok.


4

Figure 3: Database of Animation files loaded

Finally, in the selected files menu, as shown above, select the database and click open. This will load

all the files currently written to this database. If the BREZO simulation is still ongoing and files are

still being created, each additional time-step file created can automatically loaded into an open VisIT

session, by simply refreshing the database using the “Open/ReOpen” button.

IV. Viewing/Exporting Animation video/images

Contour and pseudocolor plots of various scalars can be plotted as well as the computational mesh

itself and any vector variables. These images can be output in various formats and resolutions

defined using the File>Set Save Options menu as shown below.

Figure 4: Saving Images, Curves and Bitmaps


5

The following are example plots of BREZO simulation plots created using VisIT as part of a research

project on flood modelling, carried out at the University of Nottingham.


6

VisIT can also be used to create animation and movie files from the simulation database. The

File>Save Movie option launches the animation creation dialogue shown below.


7

Some of the sample animations created using BREZO and VisIT at the University of Nottingham are

attached along with basic guide.

V. Creating Variables Using Expressions

Using the Expressions Toolbox, new variables can be created. E.g; A variable h, corresponding to the

water depth at a given point in the computational mesh can be created by defined as a Scalar Mesh

Variable type and calculated a value using the expression: eta – coord(mesh)[2]. Where eta, the

variable for the free surface elevation and coord(mesh)[2], the value of the bed elevation at a given

point in the mesh are included in the VTK file while h itself is not explicitly given. The screenshot

below illustrates the above settings. Plotting the mesh variable h would give a contour plot of water

depth throughout the domain.


8

Some more complex expressions were successfully developed for different purposes using this

facility.

VI. Node Queries/Monitoring Stations

In addition to the creation of additional variables using expressions, VisIT also allows a number

of useful queries as part of post processing. For instance, it is possible to set up monitoring

stations at any point in the mesh as a part of post processing, and plot time curves of various

variables at these points, using the Pick-related queries menu. This allows more flexibility to

BREZO users in terms of setup of monitoring stations. All the queries available are accessed

through: Controls > Query.


9

VARIABLES= "UTM Easting", "UTM Northing", "NAVD 88 Z"

ZONE T="GRID", N= 90, E=157,

DATAPACKING=POINT, ZONETYPE=FETRIANGLE

The curves above showing the variation of total wetted area with time were created using a

combination of VisIT’s user defined expression and queries facilities.

VII. Getting TRIANGLE meshes into VisIT

After creating meshes with triangle, use the makepltfile.exe utility to produce a plot file of the

mesh. This file can then be loaded and viewed with VisIT after editing some of the items in the

default file header as shown in the example below.

DEFAULT: (Tecplot Only)

EDITED: (Visit & Tecplot)

This second edited file header format makes the mesh *.plt file recognisable to both VisIT and

Tecplot.

VIII. More Help with VisIT

For more details on using VisIT, please download the manual and sample tutorial files at:

https://wci.llnl.gov/codes/visit/manuals.html

All the best with your BREZO-VisIT simulations.

VARIABLES= "X", "Y", "Z"

ZONE T="GRID", N=90 , E=157 ,

F=FEPOINT, ET=TRIANGLE

https://wci.llnl.gov/codes/visit/manuals.html

brezo-visit user instructions

Documents