Peer review is nearly impossible for the interesting bits of code. You have the same challenges as peer review of the paper itself: there aren't many reviewers

Peer review is nearly impossible for the interesting bits of code. You have the same challenges as peer review of the paper itself: there aren't many reviewers with the prerequisite technical knowledge. The majority of the time, the qualified scientific reviewers and software reviewers will not be the same people. Viz understanding CFD analytically does not mean you understand numerical algorithm implementation, or are an expert in numerical error analysis. Hell, look at the frequent evidence all over the net that the vast majority of developers don't understand ieee 754. Who pays the developers? If you aren't paying the developers much, what exactly are they going to catch in the 2-4 hours they may have to look at it? I wish I had a good solution; I think about the best we can do is community-pooled development efforts ala openfoam, bioconductor, numpy, sklearn.