Perhaps giving us a bit more information about your bike and how it's set up would make answering your question easier. I has a windshield, I assume? If so, you might benefit by adjusting the height and/or tilt of the windshield. If it lacks lower wind deflectors, you might get good results from adding a pair of those, too, as a lot of buffeting comes from air coming up from under a windshield.
2016 flhtk has lowers to house the radiator.i have a klock werks wind shield ,that solved one problem, but the air coming up beside the gas tank is terrible. my 2016 ultra never was a problem.it makes no difference if the top vent is open or closed.. no fork deflectors are available from Harley or any other
Karyakyn makes what they call an air management accessory that I've heard good and bad reports about. Some say it works and others say it doesn't and in fact makes it worse. First I'd look to see if someone previously added it and if so you might consider removing it to see if it gets better or worse. If it doesn't have it then it's something to consider. I hate products that seem to be two faced but this sure seems to be one. I'd say I've read more negative than positive reviews about it though.