Sorry for repeating myself a bit, I get it that the flight deck is supplied directly off the left pack so during normal flight there shouldn't be any recirculated air, however, when I'm getting an amazing piece of culinary delight made in the forward galley oven, it can usually be smelt very clearly in the flight deck - is this just natural air leakage coming through the bulkhead etc? I also thought the only exit path for the air would be out via the door, so the flightdeck is under positive pressure?
Also, when on the ground with APU/Packs off, there's a small amount of air coming through the sidewall vents and a fair bit from the gasper vents below the displays - I assume this is from the recirc fans pressurising the mix manifold, which then comes back down to the flightdeck via the connection to the left pack?