I think of force energy in the same way I think of Mana-based energy in Shadowrun.
Basically, in SR, creatures exist on an astral and physical plane. Some creatures are stronger on one plane over the other (for example, mundane folk have more of a presence on the physical plane; ghosts exist almost entirely on the astral plane). Objects do not really exist on the astral plane, but have a sort of "shadow" that can be seen from the astral; likewise, there are some "objects" on the astral plane that can be sort of seen in the physical plane.
That this means is that it's pretty easy for an astrally-awakened character (ie, many spell-casters) to astrally perceive and project his consciousness beyond any sort of physical wall blocking him. Corporations have got wise to this, and created living mosses that act as walls in both the physical and astral realms, to keep casters out.
Anyways.
In Shadowrun, spells are defined as either being physical, or mana-based. A physical spell moves through physical space before striking its target. A mana spell, however, does not.
What this means is that a physical fireball can be dodged by ducking behind a wall. But a mana-bolt will go right through that wall and hit you.
So, using this, a force-based spell in D&D isn't actually moving in physical space at all. It is moving through another plane (the ethereal, maybe?) and hitting your shadow form there, in pure concussive manner. It'd sort of feel like bludgeoning damage, but it wouldn't leave a mark at first. I imagine a few hours later, though, it'd leave a helluva big bruise.
This is also why force spells can hit incorporeal creatures... because they're corporeal on the plane that the force spell primarily functions from.
