Increase your smoke density, this will make you smoke in effect, heavier.

Adjust your temperature, try to imagine the actual temp of the smoke you are try to reproduce

Emitter velocities play a huge role, no matter what your other settings, your emitter velocities will always induce motion. Just lower them, generally 0.0 is too low, but something like 0.1 or so

Your emitter type is important too, for instance if you are using a simple source, you will want to generate your smoke then move it out of the way, this will keep the emitter itself from dissipating stationary smoke.

Hope that helps

question- theres this one fume kraka tutorial where he has smoke gathering at the bottom, i tried the tutorial but it still rises, whatever i do
boyancy at 0 even gravity on, but it still rises

how to make the smoke gather in a box at the bottom of a sim?
(waiting for it to be knocked down by other objects)