# 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](/files/-MVY5Q7SENUXmv2CZTl_)

![Wake aligned with the average trailing edge bisector](/files/-MVY5YIjrxCkbc4zN_gR)


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