Actually, IS and OM share few in common, if they are not totally different. Hence, you do better understand that before your indicating that you want to do IS AND OM.
As far as I know, there is no IS department at WUSTL. It once had one, but not in recent years. WUSTL has one small OM department, but those professors are very strong in their field. So, I am confused about you impression about IS at WUSTL. Also, I am not affiliated with WUSTL now, so you can ask those insiders for more inforamtion.
BTW: IS and OM are not very easy to apply as I know. The applied to admitted ratio are around 25:1, which will be higher in some top schools. Of course, if you think this ratio does not mean competitive, then I will say you are very strong candidate.
For your background, I will suggest you to check for some professors who are interested transportation science. You graduate courses on 工程数学,高等流体力学,计算机之类 may picture you as good candidate for network related research, such as dynamic user equilibrium, which require some modeling and huge amount of numerical computation. However, it is my thoughts, I may be wrong and you might be not interested in this topic or your dream school professor are not interested in this area.