Superficially, the paintings by David Mann now being shown at the National Academy of Sciences (Axis is pictured) bear some resemblance to those exhibited there earlier this year by Harvard University physicist and chemist Eric Heller. Like Heller’s computer-generated renderings of complex and chaotic physical processes, Mann’s highly abstract images suggest mechanisms such as wave motion and cellular self-organization. But Mann’s art is distinguishable from Heller’s (and that of similar artists) by his technique. Mann begins by spraying acrylic paint on a surface with an industrial sprayer. He then adds a layer of highly diluted, nearly translucent oil paint, followed by a sprinkling of mineral spirits to create a bubbly surface texture. Then Mann adds a layer of paint with a squeegee, in a way that emphasizes its tonal gradations. By repeating these steps until he’s satisfied, Mann achieves bracing visual sensations. Some of his works possess a silk-screened veneer that suggests ghostly, multilayered vortexes; Serious Moonlight uses this effect to suggest, somewhat paradoxically, the more solid curves of flint or obsidian. Mann’s other works—in such inspired color combinations as green with purple and magenta with gray—are notable for their gelatinous layers, which allow highly reflective globules of color to overlap and blend. By using such techniques, Mann, unlike most abstract painters, does much more than just hint at three-dimensionality. His work is on view from 9 a.m. to 5 p.m. Monday to Friday, to Friday, Aug. 2, in the National Academy of Sciences’ Rotunda Gallery, 2100 C St. NW. Free. (202) 334-2436. (Louis Jacobson)