Hello,
I'm trying to use a custom velocity field to influence a vellum fluid sim using popadvectbyvolumes inside the solver. I've tried a number of different setups but just can't get it working. I've been struggling with it for a couple of days mashing multiple tutorials together so hoping someone here can help?

1. Your popadvect node is not pointing to the field/volume. Its pointing to a null where you have trailed the field. Point it at the volumerasterizeattributes2.

2. On the popadvect node there is a parm called "field name". You have typed "v vel". This parameter askes what is the name of the velocity filed you want to fetch. On the volumerasterizeattributes2 you are naming your velocity field to "v", so put only that.

thank you! was thinking it's probably some simple mistake like that. I forgot the trail is just for visualisation