Abstract: A method can comprise dividing a heat exchanger design into a plurality of modules, the plurality of modules arranged in a grid, each module in the plurality of modules including: a first fluid conduit defining an inlet, an outlet, and a heat-transfer surface, and a first flow direction, and a second fluid conduit defining a second inlet, a second outlet, a second heat-transfer surface, and a second flow direction, the second flow direction different from the first flow direction; and determining a heat-transfer augmenter arrangement for the first fluid conduit and the second fluid conduit of each module in the plurality of modules based on a stress threshold of the module in the plurality of modules.