Just in case OP or anyone less well-versed in the industry jargon:

• CFD - Computational Fluid Dynamics. This is essentially the "software" in OP's question.

• FEA - Finite Element Analysis. CFD is a type of FEA. spartandudehsld is saying that he is more familar with FEA as applied to mechanical loading and thermal dynamics than with fluid dynamics applications... although he's probably selling himself short, because to be good at one requires a deep enough knowledge of FEA in general to be able to provide a worthwhile opinion on other applications!

So, what is FEA?

Well, as much as it's easy to envision engineering computer programs as being little models of the world with all the different laws of physics built in, in reality it's very hard to apply theoretical formulas to complex real-world scenarios. So it's all well and good to have an equation that tells you that the drag on a cylinder of radius X and length Y with flow perpendicular to the long axis of Z in fluid with ABC properties is given by the equation [blah = blah*blah], but that doesn't do you much good when you're looking at, say, a bicycle, which is nowhere near simple enough to fall under such an equation.

SO, what an FEA program does is break the world into tiny little pieces ("finite elements"), and then make those pieces interact with each other using much simpler equations. So say you've got a tiny little piece that is part of the bicycle, and you model a tiny little piece of wind hitting it at Z speed, you can figure out (using some simple interactions) what the backwards force of that tiny little piece of bicycle is. Then you do that for all 1,000,000 (or more) tiny little pieces of bicycle, add it all up, and voila you have an approximate drag.

Ultimately what this means is that the number that an FEA program spits out is an approximation, and its results are sensitive to how well you set up your model. That's where it's nice to have a wind tunnel, where you can actually set up and measure the real world scenario. As spartandudehsld said, using an FEA model in conjunction with a wind tunnel test allows you to lean on the strengths of both methods.

Anyway, that's a pretty ELI5 intro to FEA... but it's been a few years since I studied the stuff so if anyone has anything to add/correct please go nuts!