# SUMO

SUMO is an open source graphical tool for surface-based aircraft modeling and mesh generation  developed as part of publicly funded research projects at [KTH](http://www.kth.se/) in Stockholm. You will use SUMO to create an unstructured mesh of a NACA4412 wing with  an aspect ratio $$AR$$ of 6 and reference chord $$c\_{ref}$$ of 1. 

## Step 1

Visit <https://www.larosterna.com/products/open-source> to download SUMO. SUMO is free and it runs on Windows, MacOS, and Ubuntu. Once you download the SUMO archive, extract it and run the SUMO executable. The image below shows the main SUMO window:

![SUMO main window](/files/-MW_iIquVju6F4o5aof4)

You can create multiple body or wing components. Click the add wing button to create a wing with default parameters. The "Edit wing properties" window will open.

## Step 2

Close the "Edit wing properties" window to update the "Rendering" view tab. After closing the window you should see a wing in the "Rendering" view tab.

![Create a wing with default parameters](/files/-MW_iTyJdZXLaDNjayYb)

## Step 3

Right click on the wing name and select "Edit selected object" option. The "Edit wing properties" window will open.

![Wing with default parameters](/files/-MW_ifPFKknKoSsPkGq6)

## Step 4

In the "Edit wing properties" window, change the name of the wing object to "naca4412\_wing". Select one of the wing sections, listed in the section list, and click the "Edit section" button.

![Edit wing parameters](/files/-MW_ifPGkTsMNBux__z5)

## Step 5

Change the names of the two sections to "tip" and "root". Set the "Chord length" option of both sections to 1 and set the $$y$$origin of the "tip" section to 3. Click the "Change..." button to change the airfoil of each section.

![Change the chord length and position of the tip and root wing sections](/files/-MW_ifPHd0-S_YDMs7gc)

## Step 6

In the "Change airfoil coordinates" window select the "NACA 4/5-Series" tab. Select the "NACA 4-series airfoil" option and set the "Thickness ratio", "Relative camber", and "Max camber position" to 12, 4, and 40. These values correspond to the NACA4412 airfoil.

![Change the tip and root airfoils to NACA4412](/files/-MW_ifPIx-e5WHY3CK4k)

## Step 7

In the "Edit wing properties" window set the "Right cap height" and "Left cap height" to 0 and click the "Close" button.

![Change the right and left cap heights](/files/-MW_ifPJkH2uGiNUELpY)

## Step 8

Click the "Mesh" button to open the "Generate mesh" window. In the  "Generate mesh" window disable the "Use default values" and "Use hybrid generation algorithm" options. Set the "Maximum edge length" and "Minimum edge length" options to 0.3 and 0.01. Click the create "Create mesh" button.

![Change the minimum and maximum edge lengths](/files/-MW_ifPKNEMfBASMI3dv)

{% hint style="info" %}
Check the coordinate system of the model before meshing. The model should be in a body-fixed coordinate system i.e. the x-axis points forward, the y-axis points to the starboard, and the z-axis points down.&#x20;
{% endhint %}

## Step 9

The created mesh will be available in the "Mesh" view tab. To save the mesh to a **.stl** file click "File" and select the "Export..." and "Save surface mesh..." options.&#x20;

![Resulting mesh](/files/-MW_ifPLSyhHx-FHQqYY)

Congratulations! You created your first mesh using SUMO. Now you can use APM to analyse the flow around the NACA4412 wing.&#x20;

For more meshing information and best practices when meshing refer to the [preprocessor section](/user-guide/preprocessor.md).


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