Sandia has developed a massively parallel DNS capability for turbulent reactive flows coupled with detailed chemical reactions and molecular transport. The DNS code, S3D, is used to perform DNS code of fundamental “turbulence-chemistry” interactions in combustion at Sandia and by researchers worldwide, notably at KAUST, U. of New South Wales, U. Southampton, Tokyo Tech U., and UNIST in South Korea, among others. S3D is also used as a CFD testbed for computer science developments in advanced programming systems and in data science with in situ analytics and visualization. In addition to the physical insights gleaned from fundamental research on turbulence-chemistry interactions in combustion, the DNS benchmarks are used by the international modeling community to develop predictive models used in engineering CFD to design fuel efficient, clean burning engines for ground transportation, propulsion, and power generation. Notably, we use predictive models to enhance the performance of light- and heavy-duty direct injection gasoline and diesel internal combustion engines with fuel efficiencies upwards of 60%, while minimizing emissions of nitric oxides and soot; to utilize high hydrogen content fuels as a clean energy carrier to reduce CO2 emissions in fuel and operational flexible power generation; to explore the use of ammonia/hydrogen/nitrogen blends as a carbon-free energy carrier for power generation, and to provide reliable flameholding in scramjet applications.