# Wake

The APM Solver has several options for controlling the wake. The `wake_alignement` option in the **.conf** file controls the alignment of the wake with respect to the trailing edge. 

* By default the `wake_alignement` option is set to 0.  The wake will be aligned with the freestream velocity vector at the trailing edge.
* If the `wake_alignement` option is set to 1 the wake will be aligned with the average trailing edge bisector. The average trailing edge bisector is calculated from the normal vectors of the trailing edge elements.
* If the `wake_alignement` option is set to 2 the wake will be positioned at a specific angle with respect to the $$x-y$$plane. The `wake_angle` option in the **.conf** file can be used to specify the angle. If you do not specify an angle a default value of 0 deg will be assumed.

{% hint style="info" %}
Use the average trailing angle bisector option for best results.
{% endhint %}

The images below show the wake of  a NACA4412 wing aligned with the freestream velocity vector and with the average trailing edge bisector.

![Wake aligned with the freestream flow](https://81269019-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MV8htLPXN-_fWc_anY_%2F-MVY4vTO44DtQhh2I-lQ%2F-MVY5Q7SENUXmv2CZTl_%2Fnaca4412_wake_alignment_1.png?alt=media\&token=18e6b897-686f-42a8-b074-e4c0e7c0f01b)

![Wake aligned with the average trailing edge bisector](https://81269019-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MV8htLPXN-_fWc_anY_%2F-MVY4vTO44DtQhh2I-lQ%2F-MVY5YIjrxCkbc4zN_gR%2Fnaca4412_wake_alignment_2.png?alt=media\&token=0608b4ee-6b7b-4f2c-ae64-81a8d6f956c0)