Yes, it affects theoretically.
A bit of Heat Transfer theory.
In convection heat transfer, which is what you are talking about, the heat is transferred from the hot body to the air with the following formula:
Flux [W]=h·S·(T
hot-T
cold)
S=contact surface; h=convection heat transfer coefficient which depends on the way objects are placed, their shape etc..(depends on many things).
(By the way, Flux=h·S·(T
hot-T
cold) =(1/ R
th)·(T
hot-T
cold)
Rth is the thermal resistance which is seen in datasheets and in electronics we replace Flux by Power Dissipated as heat)
So, the important parameter I am going to focus on is "h".
In
natural convection, there are some empiric numbers which related are used to find out "h".
Here are those numbers in
natural convection:
So, as you can see, depending on the fluids involved and lots of factors, you can calculate those empiric numbers (Grashof,Prandtl) and with the specific case i.e. your "sink" and the fluid involved (air) you can calculate Nusselt's number and with it, the "h".
In those numbers, one parameter involved is the
density which varies with pressure. If you change pressure => change density => change Grashof => change Nuttselt => change "h" => change Flux.
I gave you the example with the density, but the specific heat, viscosity also varies with pressure.
With forced convection happens the same, just in this case Grashof's number is replaced by Reynold's number.
EDIT:
We frequently use heat sinks in electronics and when the heatsink itself isn't enough we ether increase the size of the heatsink or apply airflow with a fan(or through the design of an enclosure),
Heat sink => results in increase of "S" => increase of Flux
Apply airflow (Forced Convection) =>increase of Reynold's number (because it is dirrect proportional to the speed of the fluid involved) => increase of Nuttselt => increases "h" => increases Flux