We are performing extremely high resolution computer simulations of turbulence, using highly scalable computer codes on massively parallel computers, in a variety of applications. Computer simulation of turbulent combustion, whether for power plants, internal combustion engines, diesel engines, gas turbine engines, or other combustion devices, plays a major role in both improving combustion efficiency and decreasing overall pollutants. High-resolution computer simulations of tidal flow through Admiralty Inlet are being conducted to better understand the flow dynamics and its potential effects on tidal energy turbines, as well to estimate the levels of content in the water of oxygen and other important chemicals and possible effects of the turbines. Stable atmospheric boundary layers are characterized by the air near the ground being cooler than the air aloft. This condition, which often occurs on clear nights, results in suppression of turbulence and therefore less mixing of pollutants, e.g., from various combustion devices, released into the atmosphere. The latter can result in severe pollution episodes. Of particular interest is the development of models meant to simulate larger-scale flows, and the estimation of pollutant dispersion rates in these stable flow fields.