> For the complete documentation index, see [llms.txt](https://docs.whiffle.cloud/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.whiffle.cloud/getting-started/select-area.md).

# Select area

Whiffle Wind automatically suggests an LES domain based on your turbine and met mast positions, as described in Step 2 of [Under the Hood](https://docs.whiffle.cloud/getting-started/pages/gI7OQT4p6CdYKEWRO83J#id-2.-calculating-the-les-domain). However, there may be cases where a simulation does not include turbines or met masts, or where the LES domain requires manual extension, for example to encompass additional terrain features such as nearby mountains or landmasses. 

For this purpose, we provide the **Select Area** functionality. To use it, navigate to the Site step and open the **Select Area** panel. Click **Draw Area** to enter drawing mode, where you can define a rectangular area of interest directly on the map. The suggested LES domain will then be extended automatically to incorporate the additional area.

<figure><img src="/files/17Narz62MTUnurtmEHC2" alt=""><figcaption></figcaption></figure>

The LES domain can only be enlarged by drawing an area, not reduced. This ensures the LES is always of sufficient size to produce reliable results for your wind farm and turbine locations.

{% hint style="warning" %}
Manual extension of the LES domain is at the user's own discretion. Please be advised to revise our best practices below and contact Whiffle Support when in doubt.&#x20;
{% endhint %}

### Best practices

#### Including a neigbouring landmass&#x20;

To include an additional landmass or geographical feature close to your landmass, we recommend to draw the additional area only around the geographical feature. This will provide the optimal LES domain based on the additional area and turbines.&#x20;

#### Horizontal extrapolation

To enlarge the LES domain in all directions, for example when defining an area for horizontal extrapolation, draw the additional area around the pre-calculated LES domain. The domain will then automatically extend to include the added area of interest.