OpenACC has been highly successful in adapting legacy CPU-only applications for modern heterogeneous computing environments equipped with GPUs, as demonstrated by many projects as well as our previous experience. In this work, OpenACC is leveraged to transform another computational fluid dynamics (CFD) high order solver FINE/FR to be GPU-eligible. On the Summit supercomputer, impressive GPU speedup ranging from 6x to 80x has been achieved using up to 12,288 GPUs. Techniques critical to achieving good speedup include aggressive reduction of data transfers between CPUs and GPUs, and optimizations targeted at improving exposed parallelism to GPUs. We have demonstrated that OpenACC offers an efficient, portable and easily-maintainable approach to achieve fast turnaround time for high-fidelity industrial simulations.