Annexe : utilisation of fluent

2.1) Define new zones
2.2) Refine the grid
3) Patch a function to a zone

1) Custom Field Functions

It is often interesting to define new functions adapted to our problem.
For example, if you want to initialise the velocity vectors or the temperature, the Custom Field Functions are very usefull.

Write the functions you need with all the variables you dispose in Fields Functions.
Then give a name to your function

Click on Define.
There is an illustration of the use of the Custom Field Functions in the 3) Patching a function.

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2.1) Define new zones

In our simulations, we needed to impose different initial conditions of temperature in several areas.
So, we had to separate the grid. This method is allowing the definition of new zones without going back to the Prebfc program.

View of the grid before the adaptation.

Then, you must define the zone you want to separate from the grid.
Write the two coordinates (in meters) that define the rectangle area.

Then, click on Mark.
Now, you have to separate the cells you choose from the grid. For that, follow the instruction.

Grid Separate Cells

Select the hexahedron you just define in "Region Adatation" and the zone you want to separate from it.

Then click on Separate.
Note: You must Adapt and Separate the zones one after one. To adapt all the zones then to separate them doesn't work.

View of a part of the grid after the adaptation. We are able now to give different boundary conditions or initial conditions in each zone.

Example: There are different initial conditions of temperature in three zones after the patching of custom field functions.

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2.2)  Refine the grid

This is an explaination of the refinenment of the grid with an example. We will adapt the grid based on the temperature gradients in the solution of two rolls.
Before adapting the grid, you will first determine an acceptable range of temperature gradients over which to adapt

Choose the good options for the Contours.

Note: Examining the cell-by-vell values is helpful when you are preparing to do an adaptation of the grid because it indicates the region where the adaptation will take place.

Then, go back to Display Contours and select Adaptation and Adaption Function in the Contours Of drop-down list.

Click on Display.

Go back to Contours and deselect Auto Range so that you can change the minimum temperature gradient value to be plotted.
Enter a new value of 2e-06.
Click on Display.

Select Temperature and statistic temperature in the Gradients Of drop-down lists.
Deselect Coarsen under Options, so thatonly a refinement of the grid will be performed.
Click on Compute.
Now enter the value of 2e-06 for the Refine Threshold.

Then, click on Mark.
Click on Manage

Click on Display then on Adapt.

Then, you can iterate again and obtain a better solution.

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3) Patch a function to a zone

For the initial condition, it is very interesting to patch functions to differents zones.

Then select  the Variable, the Field Function and the Zones To Patch.

It is very interesting to define new zones so that you are able to patch different functions to different zones.
For example: The initial condition on temperature following.

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The Macros allow to see the evolution of different fields during the convergence.
Select Solve Monitor Command.

Click on Define Macro...
Then for example, define the macro following: Display Contours Temperature, click on Display.
Then, click on End Macro on the Monitor Commands.
Activate the macro and give it the same Command name than the name of the macro

To save a macro, write file then click return, then write  write-macro.

After the reading of the macro, look at the Monitor Command if the name of the Command is the good one.

Click on Define Macro to see if your macro is already imported.

Note: If you want to have your macro display on an other window than the residual, follow these instructions.

You can now activate several windows.

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