Creating an AIRFLOW

I am guessing that you do not have a lot of experience with After Effects. Byron's suggestion that you try using a shape layer is pretty good, but the most efficient technique depends on the kind of footage you are working with. Your sample video is a 3D amination. If your project can be done using a still image then Byron has given you one possible solution but it will probably separating the image into layers and/or creating masks or track mattes to make the graphic move through openings. 

If you are trying to add airflow graphics to footage with a moving camera then there are a lot of other considerations. The rendered 3D model of the house you gave us as an example will barely camera track, so it would be possible to add some convincing airflow graphics to the footage but it will involve a thorough understanding of Camera Tracking, working in AE's 3D space, masking, track mattes and lots more. It would not be an easy project for someone with very little experience with AE's 3D space and roto, track mattes, and compositing modes. A starting place would look something like this:

If you have access to the original 3D model and know something about the app used to create the model and animate the camera move, then it would be a better idea to explore creating the airflow effects in the 3D app. I have C4d and Blender. One is expensive, the other is Free (http://blender.org) Personally I would do the whole project in Blender. I would pick Blender over C4D because I have been using Blender for many years and I don't have to think about the UI. 

Tell us a little more about yourself and your project and maybe we can offer a little more specific recommendations.

This is how I would make it:

- With the pen create a Shape Layer giving them the path to the airflow, remove the Fill and thicken the Stroke.
- In the Stroke options of the layer, modify the start and end of the Taper.*
- Add a Trim Paths and make an animation of the airflow path.*
- Put 60% opacity on the layer.
- Add the Glow filter and configure its parameters.*
- Add the CC Vector Blur filter and give necessary parameters.*

*Follow these steps guiding you with my screenshot.