The Science DMZ model employs dedicated network infrastructures and advanced software techniques for large-volume scientific research traffic flows targeting high-throughput and low-latency data transfer. However, current Science DMZ framework lacks of efficient means of user-intent expression and suffers from slow service-delivery due to the manual work involved in the management loop. As a result, a programmable interface that facilitates user–administrator communication in a time-efficient manner is highly demanded. In this paper, we introduce FLowell, an enhanced SDN-powered Science DMZ model deployed on our campus network. Moreover, we propose a programmable policy engine atop the SDN controller that allows network administrators to implement configuration policies in order to manage the network, while simultaneously offering rapid response time network resource request policies for end users. Our experiment results show that user intent in FLowell can be responded and serviced within 1 s. In addition, FLowell reduces the network latency for the research network path by 35%, and boost the disk-to-disk throughput by up to the 10 Gbps line rate.