RBF Morph Tutorials - Mr-CFDdl.mr-cfd.com/tutorials/ansys-fluent/3D wind tunnel.pdfRBF Morph Tutorials Tutorial 1: A 3D wind tunnel 2

Tutorial 1: A 3D wind tunnel

RBF Morph for FLUENT

Current Release: V1.5

Last updated March 2014

RBF Morph Tutorials www.rbf-morph.com

Tutorial 1: A 3D wind tunnel 2

TABLE OF CONTENTS

1. Introduction ....................................................................................................................................... 3

2. Prerequisites ..................................................................................................................................... 3

3. Problem description ........................................................................................................................... 3

4. First solution: translating the cube ..................................................................................................... 4

4.1 Preparation ................................................................................................................................. 4

4.2 Source points definition and preview ........................................................................................... 5

4.3 Generating and checking the solution ......................................................................................... 9

4.4 Morph testing ............................................................................................................................ 11

4.5 Saving the solution ................................................................................................................... 14

5. Second solution: rotating the cube (first method) ............................................................................. 15

5.1 Preparation ............................................................................................................................... 15

5.2 Adjusting the set-up .................................................................................................................. 15

5.3 Morph testing and saving the solution ....................................................................................... 16

6. Second solution: rotating the cube (second method) ....................................................................... 17

6.1 Preparation ............................................................................................................................... 17

6.2 Defining the domain encapsulation ........................................................................................... 18

6.3 Defining the moving encapsulation ........................................................................................... 19

6.4 Finalizing the result ................................................................................................................... 21

6.5 Morph testing and saving the solution ....................................................................................... 22

7. Combining different solutions .......................................................................................................... 23

7.1 Preparation ............................................................................................................................... 23

7.2 Set-up of a multi-morph case .................................................................................................... 23

7.3 Previewing the combination ...................................................................................................... 25

8. Driving the calculation using ANSYS workbench ............................................................................. 27

8.1 Definition of the parametric Fluent model .................................................................................. 28

8.2 Workbench set up ..................................................................................................................... 29

8.3 Run the calculation ................................................................................................................... 30

9. Summary ......................................................................................................................................... 31

10. references ................................................................................................................................. 31



1. Introduction This RBF-Morph tutorial is termed "A 3D wind tunnel" and has the objective to provide the user with the guidelines for setting up and solving a morph study. To achieve this target, the practical use of the basic commands and features of the code will be described, and all foreseen steps required to accomplish a complete morph analysis according to RBF Morph tool [R 1] will be deepened.

This tutorial demonstrates how to do the following:

define source points by means of different approaches;

preview source points in the baseline and morphed configuration;

generate and check the solution;

load and adjust an existing solution;

list the surfaces effectively involved by the encap action;

accomplish the morph testing and save the adjusted solution;

reset a solution;

set up a multi-morph solution.

2. Prerequisites Requirements for working this tutorial:

1. you are working in the directory where the tutorial problem resides;

2. you have just started the Fluent-GUI application.

3. Problem description This tutorial is useful to acquire the essential functionalities of RBF Morph. The case study is a simplified external aerodynamic problem.

The geometry of the model consists of a perfect cube which is immersed into a box defining the virtual wind tunnel. The edges of the cube are 1m long and its surfaces, called cube, are parallel to those of the wind tunnel in the baseline configuration. The wind tunnel is 10m long, 5m wide, and 3m high respectively along x, y, and z axes of the global reference system. The cube is positioned onto the ground surface at 3m from the inlet surface and at 6m from the outlet surface. The remaining surfaces (lateral and top) are termed tunnel. The surface mesh of the model is reported in Figure 1.

Figure 1: Surface mesh of the wind tunnel model



To achieve the objective of the tutorial, the effect of the cube translation along x axis and its attitude angle, at first as individual solution and then as combined solution will be investigated. As concerns the solution set-up, the cube translation will be accomplished by means of the features of the Surfs panel only, whilst, relating to cube rotation, two different techniques will be presented involving one of the encapsulation feature of RBF Morph as well.

4. First solution: translating the cube The position of the body along the wind tunnel is a very important topic. In the baseline configuration, the cube is close to the inlet because the flow pattern in the undisturbed area can be captured easier than in the wake region. As such, to investigate the influence of the cube position a movement along x direction is then of interest.

This task can be carried out by adopting several strategies. The simplest procedure employed in this tutorial foresees exclusively the use of Surfs panel capabilities for the definition of source points. All mesh nodes belonging to the cube surface are utilized to define the first set of source points prescribing a rigid movement (displacement along x axis). All mesh nodes of the tunnel, inlet and outlet are used to define the second set of source points constrained through a null rigid movement, whereas all areas without a prescribed motion, namely the ground and the volume mesh, are left morphable by default.

The basic operations for the execution of this tutorial are described in the following steps.

4.1 Preparation After starting Fluent from the directory containing the tutorial files:

read the test case tut_01_wind_tunnel_cube.msh.gz;

open the RBF Morph GUI via the menu Define -> RBF-Morph;

load the library by clicking on Enable RBF Model.

Once the library is completely loaded, the panel illustrated in Figure 2 should appear.

Figure 2: Config panel

Various panels are available in the GUI through the radio buttons on the left sidebar (Main Sidebar). The standard set up process of RBF Morph usually requires to use the panels from top to bottom. At the



bottom of the sidebar there are some graphics settings which are available at any time (Graphics Sidebar).

Tip: in case previous settings have been used of saved in the .cas file, it is in general possible to re-initialize the set-up by clicking the Reset button.

4.2 Source points definition and preview As previously stated, in the first part of the tutorial, the definition of source points is accomplished by means of the use of the Surfs panel only. According to this strategy, start the set-up switching to the Surfs panel in the Main sidebar as depicted in the Figure 3.

Figure 3: Surf panel

Two surface sets are needed and, accordingly, the set-up can proceed as follows:

define two surface sets by acting on the arrows of the Number of Sets field, which add or remove surfaces sets (see Figure 4 on the left);

the current surface set to be edited can be selected by acting on the arrows of the Set field;

in the first surface set, all points on the zone cube must be selected. To do this, select cube in the Select Surface list;

assign the name Cube to the surface set on the right of the Set field;

to prescribe a motion of the current surface set, click on the Set M button and the panel Set Motion will be opened as shown in Figure 4 on the right. Impose the rigid motion by setting the DX value to 1m and confirming by pressing the Set button;

close the Set Motion panel by clicking on the OK button (alternatively the Set Motion panel can be left open as it is automatically linked with the current surface set under editing);

to save the settings of this first surface set, press Set button.

Selected surfaces of the current surface set can be displayed in the graphic viewport using the Disp button.



Figure 4: Set-up of the surface set 1

It is then possible to prescribe the second surface set adopting the same procedure of the first one. To this end, proceed as follows:

change the active surface set to 2 by using the arrows of the Set field;

select the inlet, outlet and tunnel surfaces in the Select Surface list (see Figure 5 on the left);

assign the name Tunnel to the surface set;

click on the Set M button and the Set Motion panel will be opened. Leave the default motion (null motion) in the Set Motion panel as these zones have to remain fixed (see Figure 5 on the right);

confirm the defined motion by pressing the Set button and then close the Set Motion panel by clicking on the OK button;

to save the settings of the second surface set press Set button.



Figure 5: Set-up of the surface set 2

All settings for the Surfs panel are now completed. The result of the settings in terms of source points and their new position after morphing can be preliminarily previewed by carrying out in sequence the following actions:

1. click the Finalize button. Once all source points from all the defined surfaces sets in the Surfs panel are collected, both DispPts and PrevPts buttons are enabled;

2. display the source point by clicking on the DispPts button. Figure 6 illustrates what should be reported on the screen, namely all defined source points (defined source points belong to either cube, or tunnel, or inlet, or outlet);

3. preview the final position of source points after morphing, by clicking on the PrevPts button. Figure 7 illustrates what should be reported on the screen.



Figure 6: Preview of the distribution of source points

Figure 7: Preview of the location of source points after morphing

It is worth to remind that the latter task can be also performed afterwards in the Solve panel, where all source points effectively defined are collected from all definition panels (Encaps, Surfs and Points).

Source points, source points displacement, and morphing domain completely define the RBF problem. These information will be then processed by the solver to calculate the RBF solution.



Tip: it is crucial, in view of preventing inconsistent movements between zones or wrong definitions of the problem, to perform the source points preliminary previewed in both the baseline and morphed configurations.

4.3 Generating and checking the solution Once all settings of the solution set-up are completed, it is possible to switch to the solution panel by selecting Solve in the Main Sidebar. The panel shown in Figure 8 appears. After pressing the Source Points button, all source points are collected, the Solution, DispPts and PrevPts buttons become active, and some information are printed in the Fluent shell.

Figure 8: Solve panel

Before executing the solution, it is good practice to utilize DispPts and PrevPts capabilities to carry out a preliminary check of the correctness of settings similarly to what already described in the previous paragraph. In case this first verification succeeds, and so the solution consistency is positively verified, the solution process can be executed by pressing the Solution button. Make sure that no errors have been occurred by reading the information that are reported in the Fluent shell summarizing the solution computing.

Before accepting and saving the solution for subsequent use, it is strongly advisable to preview in detail and check the actual effect on the mesh. This task can be performed by exploiting, in sequence, the capabilities of the feature of the Preview and Morph panels.

In particular, the feature of the RBF Morph Preview panel allows the user to qualitatively preview in detail the morphing action without changing the actual mesh. With this purpose, select the Preview item in the Main Sidebar. In the Preview panel it is possible to select Preview Surfaces and Original Surfaces, and, using the Preview button, preview them in the standard Fluent graphic viewport. Moreover, the panel contains other information as the name that is currently used in the Solution field. If the solution has not been saved yet, the name default will appear in this field.

As example, select cube and ground surfaces in both surface lists (eventually using the Sync buttons to synchronize the lists) as shown in Figure 9 and use the Preview button with two different values of the Amplification (1.0 and 2.5) to display the corresponding effect on the screen.



Tip: in many cases, it is an useful practice to create cut planes by means of the standard Fluent commands, and then preview the morphing results on them. The planes created will appear in both lists of Surfaces of the Preview panel.

Figure 9: Preview panel

Figure 10 and Figure 11 report, for the cube and ground surfaces, the preview of morphing with respect to the baseline configuration for an Amplification value of 1 and 2.5 respectively.



Figure 10: Morphing preview with amplification 1

Figure 11: Morphing preview with amplification 2.5

4.4 Morph testing The most reliable method to check the actual effectiveness of morphing is the morph test, that can be performed through the feature supplied by the Morph panel. By means of this tool, it is feasible to morph the entire mesh and, then, recur to the Undo function to go back and check from time to time the deterioration of mesh through monitoring parameters.



To run the morph testing, enable the Morph item in the Main Sidebar as illustrated in Figure 12.

Figure 12: Morph panel

In the Morph panel, after the definition of the proper amplification factor, it is feasible to modify the mesh by pressing the Morph button. The Undo capability is enabled by default (if not enabled, enable the Enable Undo option) and can be used to revert the mesh to the original configuration. A Morph/Undo sequence is crucial to assess the quality of the mesh for different amplification factors in order to verify the presence of problems such as negative volumes or left-handed faces that can not be detected via Preview panel functionalities.

It is also practicable to select the fluid zones to be affected by morphing action enabling the Select Fluid Zones box. If individual fluid zones are then selected, special care must be taken to avoid inconsistent movement of nodes at the interface of different fluid zones.

For the present tutorial, some results are collected in the following table.

Table 1: Mesh quality depending on amplification value

Amplification Maximum Cell Skew

A=0.0 (baseline mesh) 7.46 e-01

A=0.5 8.79 e-01

A=1.0 9.54 e-01

A=2.5 invalid mesh

Figure 13 shows the surface mesh of cube and ground surfaces after morphing with amplification 2.5.



Figure 13: Surface grid after morphing with amplification 2.5

When an invalid mesh is generated, an error message appears. In these cases, to investigate in detail the problem, the NegVol button can be used to display the negative cell centroids (see Figure 14) over the current displayed mesh without the need for initializing the case. This feature works in parallel sessions as well, and it is a clear advantage for large cases.

Figure 14: Negative cells centroids visualization

For small models it is viable to assess the effect of morphing on the entire mesh using the Morph panel during the same serial session. Since this step may be time consuming for large models,it is alternatively



possible loading the same solution in a parallel session, eventually with the GUI activated to interactively investigate the result.

4.5 Saving the solution After the solution has been checked, this can be saved in the Solve panel by specifying the file name move-x in the File box and by clicking on the Write button. The file name has to be specified without any extension as shown in Figure 15.


Two files will be created in the working directory, move-x.sol and move-x.rbf. The first file contains all information related to the solution, whilst the second file includes the standard configuration file that allows to restore all data in the RBF Morph GUI. Since the solution file may be quite large due to morph calculation complexity, it is usually saved in binary format (default option) to save disk space.

Tip: if the Fluent cas file is saved after setting up the RBF Morph, all current settings will be saved in the cas file and restored the next time the cas file is read. In addition to this, if the RBF Morph library is opened at the time of saving, when the cas file is read again it will try to load the library. If the morphing stage will be done in a different session, then it is not necessary to save the cas file after the RBF Morph setup, as everything is stored in the .rbf file; in any case it is recommended to unload the RBF Morph library before saving the cas file, by disabling the check Enable RBF Model button.



5. Second solution: rotating the cube (first method) This solution can be set up either by carrying out slight modifications to the previous one utilized for the translation of the cube or, alternatively, adopting a completely different approach. The first method is described in this paragraph, whereas the latter one in the next.

5.1 Preparation To adjust the existing solution, it is viable to continue from the previous session providing that the mesh is in the original configuration (displaying the position of the cube for instance).

Otherwise a new session can be started, and then the mesh and configuration file can be. To read an existing solution set-up, open the Config panel (previously shown in Figure 2) and specify the file name with or without extension and click on the Read button (alternatively you can use the Select button).

5.2 Adjusting the set-up All settings can be left unaltered with the only exception of the rigid motion applied to the cube. The rigid motion can be changed from the Surf panel by selecting the Set number 1 (Cube) and clicking on the Set M button. In the Set Motion panel a rotation around a vertical axis located at the centre of the cube shall be prescribed by assigning the values reported in Figure 16 on the right. Before accepting the modified surface set 1, verify the location of the rotation axis by clicking on the Display Axis button in the Set motion panel. What depicted in Figure 16 on the left should appear on the screen.

Figure 16: Rotation axis visualization and rotation parameters values

To confirm the adjusted motion, press Set button, then close the Set Motion panel by clicking on the OK button, and the click on Set button of the Surfs panel.

It is worth to highlight that a rotation angle of 1 deg can be used with the aim to have the actual angle directly expressed by the amplification factor.



5.3 Morph testing and saving the solution Since all information to preview, and check the morphing solution have already been detailed, all strictly necessary steps to generate, save and check the new solution are summarized as follows:

activate the Solve panel;

click on Source Points button;

click on Solution button;

activate the Morph panel;

set Amplification to 1;

click on Morph button;

click on Undo button;



click on Undo button.

Also in this case the mesh quality evolution is observed and the result on mesh can be inspected.



A=0.0 (original mesh) 7.46 e-01

A=1.0 7.48 e-01

A=10.0 7.87 e-01

Figure 17 illustrates the ground mesh morphed with an Amplitude value of 10.

Figure 17: Ground mesh after morphing



Once the solution has been checked, it is possible to save it in the Solve panel by specifying the file name rotate-z in the File box and by clicking on the Write button. The file name has to be specified without any extension as shown in Figure 18.


6. Second solution: rotating the cube (second method) In this part of the tutorial the encapsulation feature of RBF Morph is explored to differently accomplish the same solution task described in the previous section.

In general, source points can be selected exploiting encapsulation domains which can be very complex utilizing the multi-encap feature. The rotation of the cube can be imposed for exampe using two simple encapsulations, namely one domain and one moving encap. In particular, the domain encap serves to limit the action of the morpher to a portion of the mesh surrounding the cube only, whilst the moving encap imposes a rigid motion (the rotation) to all mesh elements that are included into it. Among available shapes for encapsulation, in this example the cylinder and box will be used respectively as a domain and moving encaps.

6.1 Preparation Before preparing the new solution set-up, reset the solution by clicking on the Reset button in the Config panel already shown in Figure 2 and accepting by pressing OK button in the warning panel shown in Figure 19.



Figure 19: Warning panel

6.2 Defining the domain encapsulation Once the solution has been deleted, the encapsulation domain has to be defined by selecting the domain in the top drop-down list and by setting the Number of Items field to 1. Then source points spacing Resolution is set to 0.1m and the encapsulation Type is set to cylinder. The auto set-up feature Setup From Parts can be used to place a cylinder around the cube. Then the Modify buttons + and – can be used to adjust the shape. The final result for this tutorial is obtained by pressing the button + two times and keeping all the increment value for DR, DP1, and DP2 fields respectively set to 0.5, 0.1, and 0.5m as reported in Figure 20.

Figure 20: Domain encaps set-up

Once the domain encap set-up has been accepted by pressing the Set button, the encap can be represented in the graphic viewport by pressing the Disp button (see Figure 21 in which the tunnel surface is also selected for visualization after disabling Edges in Mesh Display panel).



Figure 21: Domain encaps visualization

Moreover, if the option button Show Encap is enabled, the graphic is refreshed in real time when the buttons + and – are pressed. All the encap settings are confirmed using the Set button.

Tip: to check the encapsulations it is possible to use the buttons + and – in the same sequence order to see the effect and then restore to the original shape.

6.3 Defining the moving encapsulation The moving domain has to be defined in a similar way, but by selecting the moving field. The encapsulation Type is now set to box, the Resolution is still set to 0.1m and the Setup From Parts feature is used again to place a box around the cube. The encap is then increased of 0.05m by using the + button one time.



Figure 22: Moving Encaps panel

The moving encap can be represented in the graphic viewport pressing the Disp button (see Figure 23).



Figure 23: Moving encaps visualization

Using the Set M button, the panel Set Motion is opened and the same rotation imposed in the previous example (see Figure 16) can be specified. All mesh nodes inside the defined box will be moved rigidly with the assigned motion. The encap settings are confirmed using the Set button.

6.4 Finalizing the result After defining all the encapsulations, using the Finalize button the source points will be calculated and a summary will be printed in the Fluent shell. With the Display (see Figure 24) and Preview buttons it is possible to display in the graphic viewport all the defined encaps and preview their movements.

In a similar way with DispPts (see Figure 25) and PrevPts buttons it is possible to display the generated source points.

Figure 24: Encaps visualization



Figure 25: Source points visualization

Furthermore, after the Finalize operation, the SetThr button is enable. This function can be used to generate a list of all the mesh zones “touched” by the encap (i.e. with at least one node inside). The touched zones can be then displayed using the DispThr button.

Tip: after Finalize has been executed, in the panel Tools it is possible to limit all the surface lists in the RBF Morph panels to the touched zones only, by checking the Show Only Encapsulated Threads button.

6.5 Morph testing and saving the solution As before, all necessary steps to generate, save and check the new solution are summarized as follows:

activate the Solve panel;

click on Source Points button;

click on Solution button;

specify the name rotate-z-encap in the File box and click on Write button;

activate the Morph panel;



click on Undo button;



click on Undo button.

Also in this case the mesh quality evolution is observed and the result on mesh can be inspected.





A=0.0 (original mesh) 7.46 e-01

A=1.0 7.50 e-01

A=10.0 8.45 e-01

7. Combining different solutions In this tutorial the advanced feature of Multi-Sol is explored. Multi-Sol can be used in both interactive and batch mode. It basically performs the task of combining several solutions together, superimposing them, i.e. the displacements of each solution are always calculated on the original mesh and then summed to obtain the final deformed configuration. This tool is very efficient because it allows to use the stored modifiers without rebuilding the solution and, moreover, it can be used in parallel.

The Multi-Sol capability is available in both in serial and in parallel, using the GUI Multi-Sol panel or the TUI command (rbf-morph). The GUI allows to predict in advance the effect of the modifiers combination and to preview the mesh, whilst DOE and optimisation tasks can be easily performed in batch thanks to the TUI command (rbf-morph) that transforms the original Fluent mesh in a true parametric CFD model.

7.1 Preparation For this solution it is possible to continue from the previous session, but making sure that the mesh is in the original configuration and that the configuration is reset by means of the Reset button in the Config panel. Otherwise a new session can be started and the mesh file must be read again.

If all the tutorials have been executed, the working directory should now contain 7 files:

move-x.rbf;

move-x.sol;

rotate-z.rbf;

rotate-z.sol;

rotate-z-encap.rbf;

rotate-z-encap.sol;

tut_01_wind_tunnel_cube.msh.gz.

7.2 Set-up of a multi-morph case To perform a multi-morph calculation, activate the multi-solution panel by checking the Multi-Sol option in the Main Sidebar and selection Multi-Sol as type of execution as depicted in Figure 25.



Figure 26: Multi-sol panel

Then the first two solutions have to be enabled by specifying the corresponding names and amplification values in the proper fields. In this example, the desired combination is a translation 0.5m and a rotation of 10deg of the cube, i.e. the solution move-x will be set with an amplification of 0.5 and the solution rotate-z with 10 (see Figure 27).



Figure 27: Multi-solution panel set-up

The settings can be confirmed using the Set button, which, after solutions reading, will also suggest the corresponding TUI command in the Fluent shell: (rbf-morph '(("move-x" 0.5)("rotate-z" 10)))

Note that to make Fluent properly locating the solutions, all the required files must be in the working directory where Fluent was started from.

Tip: in alternative, if Fluent started (or even read a file) from a different directory, the following command can be used to make it pointing to the directory containing the RBF files:

(syncdir “complete-path-of-working-directory”).

7.3 Previewing the combination The Preview button, when pressed the first time will move the GUI to the Preview panel that appears with the amplification disabled and with <multi-sol> as the solution name, the user can now configure preview items and after pressing the Preview button will be redirected to the Multi-Sol panel to have the freedom to tweak the amplifications as desired without the need to activate the Preview panel again. Note that the Morph and Preview panels will be available anyway with the solution name changed in a similar fashion.



Figure 28: Preview panel

The combined effect on the whole mesh can be previewed or explored with the Morph command to check the mesh quality.

In this example Fluent will report:

Maximum Cell Skew = 9.25 e-01

Different combinations can be explored. The mesh has to be restored with the Undo button, and a new combination can be set in the Multi-Sol panel, using the button Set. Just for making another example, if the sign of the x movement is reversed, the output message will be:

(rbf-morph '(("move-x" -0.5)("rotate-z" 10))) )

and a new Morph operation will give:

Maximum Cell Skew = 8.98245e-01.



Figure 29: Morphing preview of the first multi-solution

Figure 30: Morphing preview of the second multi-solution

8. Driving the calculation using ANSYS workbench In this tutorial the coupling with ANSYS Workbench is explored. The Fluent model is first transformed in a parametric case using standard Fluent options that allow to define input and output parameters. It is then inserted in Workbench as a calculation cell and exposed parameters are explored using a table.



8.1 Definition of the parametric Fluent model After starting Fluent from the directory containing the tutorial files, read the test case tut_01_wind_tunnel_cube.msh.gz.

The input parameters to be defined are:

the inlet speed;

the cube attitude angle as defined in the shape modification rotate-z.

The cube attitude angle is controlled defining a custom input parameter with the TUI command:

(create-custom-input-parameter "rotate-z" 0 'none)

In which parameter name, initial value and units are specified. The user can define as many input parameters as desired. The velocity inlet parameter is defined in Fluent Boundary Conditions panel selecting “inlet” and pressing the Edit... button. In the velocity field replace “constant” option with New Input Parameter and set the velocity-1 parameter at 10.

Created parameters can be edited in the Parameters window activated in Fluent Boundary Conditions panel by the Parameters... button (Figure 31). The force output parameter is created from this window using the command create Forces... and then selecting the cube and exporting the parameter with the Save Output Parameter... button.

Figure 31: Fluent Case parameters.

Once parameters are created is time to link the shape of the model to shape parameters and to define how the case is initialized at each design point. Go to the Solution Initialization panel and activate “Hybrid Initialization” option. Go to the Calculation Activities panel and enable “Automatically Initialize and Modify Case”, press the Edit... button and in Case Modification tab enable “Pre-Initialization”. The morphing command has to be executed before calculation so fill the field with the following morphing command:

(rbf-morph (list (list "rotate-z" (get-custom-input-parameter "rotate-z"))))

Notice that the “list” command is used to define the morphing list in the rbf-morph command. This is required to process commands inside the list. In this case the “rotate-z” solution is used with the

amplification retrieved from the “rotate-z” parameter by the get-custom-input-parameter

command. Set the iteration of each run to 50 press OK button and answer No to the dialog box question (Figure 32).



Figure 32: Fluent Case Initialization Settings.

The Fluent case is now parametric and can be controlled in stand alone (just open the case set the parameters and press the Calculate button in the Run Calculation panel) or using Workbench.

Save the parametric case with the name tut_01_wind_tunnel_cube_par.cas.gz.

Tip: in a generic set-up, in which several shape parameters have to be combined, add more custom parameters

using the (create-custom-input-parameter "par-i" 0 'none) command; using for the parameter

name the same name of the RBF is not mandatory but a suggested practice. Remember to extend the morphing

list (rbf-morph (list (list "par-1 " (get-custom-input-parameter "par-1")) (list "par-2 " (get-custom-input-parameter "par-2")) ... (list "par-n " (get-custom-input-

parameter "par-n"))))

8.2 Workbench set up Open Workbench and save the project using the name DX. Insert a Fluent cell in the Workspace. Import the tut_01_wind_tunnel_cube_par.cas.gz in the cell. Exit Fluent using “Close Fluent” in the File menu of Fluent. Save the WB Project.

The project layout will look as in Figure 33 with Parameters connected to the Fluent cell. RBF Morph solution files are required in the working folder so copy rotate-z.rbf and rotate-z.sol in \Tutorial-01\Clean\WB_files\dp0\FLU\Fluent.



Figure 33: Workbench set up.

Activate Parameters panel and fill the table using the same data of Figure 33 (speed at two levels 10 and 20, angle at four levels 0 15 30 45).

Figure 34: Workbench parameters set up.

8.3 Run the calculation Refresh the Project using the command “Update All Design Points”; at the end of the calculation the results will be available in the table as represented in Figure 35.



Figure 35: Workbench parameters results.

9. Summary This tutorial demonstrated guidelines for setting up and solving a morph study of an external aerodynamic problem. The main passages to perform a Morph study were detailed with particular reference to the definition of source points, the generation and storing of the solution. Moreover, the features to preview and check the solution were presented. Information to control the shape parametric Fluent case are then provided to complete the study.

10. references R 1. Biancolini M. E., Mesh Morphing and Smoothing by Means of Radial Basis Functions

(RBF): A Practical Example Using Fluent and RBF Morph, Handbook of Research on Computational Science and Engineering: Theory and Practice, 2 vol. pages 347-380, 2012.

Documents

RBF Morph Tutorials - Mr-CFDdl.mr-cfd.com/tutorials/ansys-fluent/3D wind tunnel.pdfRBF Morph Tutorials Tutorial 1: A 3D wind tunnel 2