The paper focuses on the use of petascale simulations to address the open-ended problem of scaling-up continuous flow processes in microfluidics. Some of these processes are mixing limited and so require deep analysis of the scale up effects onto the mixing performance. The scaling up strategy considered is the so-called sizing-up approach based on the conservation of the turbulent dissipation rate in the reactor combined with petascale simulations. High fidelity Direct Numerical Simulations are performed from micro- to milli-scale reactor (up to 11 billion of mesh nodes on 131,072 processors) while maintaining the same accuracy of the physical phenomena description (smaller dissipative scales). It leads to confident qualitative estimations of the mixing performance for the different sizing-up scenarios. We show that it is possible to increase up to two orders of magnitude the production rate of the continuous reactor while maintaining an excellent mixing quality, which is very favorable for the material synthesis process.