Matisse' manual


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Preliminaries

Creating a project

Creating data

Importing data

Creating the boundary of the domain

Preparing the mesh (MNT)

Creating the mesh

Creating the boundary conditions

Introduction

Here are a few generalities about how to use the software matisse. Matisse is used by Telemac 2D in order to generate a mesh and write the boundary conditions for the code Telemac. It is not used for any calculation.

In this manual, we are going to see an example, it is the creation of the mesh of a river. It is a real example, and the following mesh has been used with Telemac for the BEI. So you are going to see, how it has been made step by step, and therefore, you should be able to do another one by following the same steps.

It is a lot easier to understand how Matisse work by doing an example as you read the manual. This is why we included in this report file which is used in this tutorial in order to import the data. Here is the link for this file.

Preliminaries

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Creating a project

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Once Matisse has been open, it is necessary to create a project. Physically, this project is a directory (name.MAT) in which the software is going to stock many folders.

Click on "projet, Nouveau" select "projet vide", then click on "nom du repertoire", enter the name of your directory and finaly validate your choices. Another window opens, click again on "valider".

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Creating data

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Once the project has been open, it is necessary to create data. There are two ways to create bathymetric data:

Click on "données, créer point". Enter the postision in a cartesian coordonate system in th X and Y boxes and then enter the bathymetry of the point by filling the box Z, and then validate by clicking on "valider". This way of doing so is really fastidious because all points have to be entered.

Click on the "lignes geo" step and then select "données, créer ligne". You can now click with the mouse on different points of the domain. Once all the points of the line have been selected right click in order to validate the line. A window appears: click on "Fixer" and then choose the bathymetry of the line and finally validate your choice. All the points in the line are added at the same height. They are all linked with a line. This way is a lot faster because the points are added to the domain with the mouse. The coordinates of the points do not have to be written down.

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Importing data

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As it can be seen, creating data with Matisse can be really boring especially if you have to enter all the coordinates of all points. Therefore, it is also possible to import data. There are two different format frequently used for importing data: The XYZ format and the SinusX format.

With this system, all the data are allready available in document in the text format.

Therefore the only thing which has to be done is to import the data: Click on the "lignes geo" step and on "données, importer lignes/points". This action opens a window which ask you where Matisse has to find the folders containing the data. First choose the directory where the folder is located using the left browser and then select the document which has to be read using the right browser. It is then really important to select the right format for the document which has to be read. Choose SX for a document in the SinusX format and XYZ for a document in the XYZ format. Finally click on "valider" in order to validate your selection.

A second window appears: Choose the unit of the coordinate system by clicking in the first box and the n validate.

Normally if you it should close that window and then you should be able to see the lines on the screen. If you can't see any lines, you can try to click on "vue globale" in order to zoom out and to see the whole domain. There are sometimes some problems if you use text documents under a unix station. Indeed if you have created your text document with a windows system, when it is imported under a unix system the return key becomes ^M and therefore the document is not readable anymore by Matisse. This is really tricky because the text editor do not show on the screen the ^M. Therefore the document has to be corrected by unix. You should use the commande dos2unix: Write in a Terminal: dos2unix name1 > name2. It creates a document (name2) readable by Matisse from the document name1.

This an example of what it could look like after these opeations:

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Creating the boundary of the domain

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Once you have your bathymetry on the screen, Matisse needs to know what is the boundary of the domain. This is the limit of the domain where Telemac is going to do some calculations. From the example above, the black line is the boundary of the domain, and the white lines are bathymetric lines. as you can see, the black line is not a closed line. Therefore, it has to be closed in order to form the domain of the future mesh. Therefore, the end points have to be connected.

Left click on the two end points of the boundary line. They should appear in red.

And from the "action" menu choose "connecter". This connect the two points and make a circle line.

As you can see, this line crosses some other lines, but it does not know which bathymetry it should have when it crosses these lines and in between the knots. Therefore it is necessary to interpolate the bathymetry: Otherwise, the line which connect the two points always have the same bathymetry and it creates a wall on the boundary of the domain. It is only necessary to interpolate the bathymetry between the two points which have been connected. Thus we should cut the line before these points. This is achieved by clicking on "scinder" in the "action" menu.

Then some hard points have to be defined. It's the points which won't move during the interpolation. Therefore, all angular points have to be defined as hard points. Click on the angular points, in this case the two end points, they are shown in red and then click on "définir points durs" on the "action" menu. The following window appears. Click on "dur" and validate.

Push the "esc" button on the keyboard in order to unselect the points, they should appear in yellow.

Finally, you can interpolate by selecting the line itself: click between the points, on the line. Only the line should appear in red. And choose "projeter ligne" from the "action" menu.

Connect the yellow points to the rest of the line. We know have a round line around the domain which has to be meshed.

This line has now to be defined as being the round line which delimits the domain. Click on this line, only this line has to be selected (in red).

And click on "editer type de ligne" from the "edition" menu. The following window appears:

Click on "contour" in order to define it as being the boundary of the domain and validate. We are now ready for the next step: the M.N.T.

Save again before you click on the M.N.T button.

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Preparing the mesh, the MNT mode

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The MNT, is used to define where on the domain, you want the mesh to be well defined, and where, you want the mesh to be not as tightly made. This is why you define a "critere" for each region of the domain. The "critere" is an indication of the number of nodes on a region. When you click on the MNT button, the points on the domain change, you now see that:

If for instance you want if you want a node every 10 meters, on one line here, the river. You first have to select it.

And then select "calculer critere" from the "action" menu. The following widow appears:

The "operateur" is the operator you want to use for instance, here we are going to use a constant as the operator. Select constante. Click on the box just above "detruire" and write the name of the "critere" and then enter. Go then on the box on the left of detruire, and write the value of the constante, here we put 10 because we want one node every 10 meters on the river. And finally on "appliquer" in order to validate your choices. Here is what you see:

Now you want to define the number of nodes on the rest of the domain. So you select "complementaire" from the "definition du domaine" box, the effect of this action is to select everything but the river. And then you go over the same steps: (select "constante", put the name of the critere, enter the value of the constant and finaly validate. We now have this:

So now we have a critere for the river and one for everything but the river, we need one for the whole domain: So you push the "esc" button in order to unselect everything and choose "tout selectionner" from the "edition" menu. The whole domain should appear in red. Click again on "calculer critere" from the "action" menu and choose c10 as the "1er operande" max(x,y) as the "operateur" and c100 as the "2eme operande". The "1er operande" is "x" in "max(x,y)" and the "2eme operande" is "y". Choose the name of the critere and validate. We had a critere for two different region and now, we have a critere for the whole domain. It choosed the most precise critere on the domain.

We have finished the M.N.T step, so before we go to the next step, we have to save again.

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Creating the mesh

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Click on the "maillage" step. We want the nodes of the mesh to be on the river, therefore, we want to force the mesh to have its nodes on a line. So click on the line (the river) in order to select it, and click on "calculer maillage" from the "action" menu. It opens a window asking which critere should be used. click on the one you need. The only critere which are shown in this window, are the critere which can be used for the whole domain.

Validate the selection, after a few seconds, it should tell you the estimated number of nodes, it should not exceed 30.000 otherwise, it is really too long for telemac to calculate.

Click on "continue" and wait for Matisse to calculate the mesh. After a minute or so you see:

You now have to create a folder containing all the geometric information needed by Telemac. Click on "generer fichier Telemac" in the "projet" menu. Choose where you want to put the folder containing all the information, and validate.

Matisse works for a minute or so and ask you if you want to renumber the nodes, validate.

And save.

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Boundary conditions

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First we need to create groups, a group is a an ensemble of nodes of the boundary which have the same function. For instance, you can define an inlet, an outlet and a wall. This is what we are going to do. Click on the "conditions aux limites" step, all the boundary nodes turn to blue.

We now have to select which nodes we want to group together: Click on "selectionner enveloppe" from the "edition" menu, and make a line around the points you want to group.

Right click on the mouse, all the points located inside the line turn to red.

Click on "creer groupe" from the "donnees" menu, the following window appears:

Write the name of the group in the first box, choose the color of the group and validate. Create as many groups as necessary.

Now we need to define some boundary conditions: Click on "creer entité" from the "donnees" menu. The following window appears, choose the name of the "entité" and choose which boundary conditions it uses (on H, U, V and T which is a tracer). In the examble, we choose to enforce a flow: H (the height of the flow) is free, U and V (the speed of the flow) is determinated and T is free.

We know have to associate a group to a boundary condition. This is done by clicking on "associer groupe-entitee" from the action menu.

Click on one group and then on one boundary condition and click on "appliquer" in order to validate as many times as necessary.

The last thing to do is to generate the folder containing all the boundary conditions. Click on "generer fichier CONLIM" from the "projet" menu. Choose where you want to create it, and its name and validate. You should put the conlim file and the geometry file (telemac file) in the same directory, they are used by Telemac at the same time.

Save and quit.

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