instead, the attainment of a complete and "perfect" model would be impractical if simple models that require 10% of the "perfect" model's calculation time can adequately predict an acceptable level of accuracy, say 90%, of the considered process

It follows that such incompleteness would help to focus and deal with the detailed calculation of the specific electrospinning portion of interest.

첫번째 문장에서 마지막 say 90%, of the considered process 이부분이 어떤걸 의미하는지 잘모르겠습니다.ㅠ
어떤 문장이 도치된건지, 무엇이 무엇을 의미하는지 해석 시도 조차 못하겠네요ㅠ

제가 일단 해석한 건 

대신에, 완벽한 모델을 얻는것은 비현실적이다.
만약 완벽한 모델의 계산시간의 10%정도만 요구되는 간단한 모델은 납득할만한 정확도 수준을 충분히 예상할수있다.(say 90%, of the considered process)

이러한 불안정성은 집중(?)하고 흥미로운 특별한 전기방사 부분의 자세한 계산을 다르는데 도움을 줄것이다.