A heat-management device includes an array of recesses distributed across an external surface of a thermally conductive body. The device includes an array of protrusions interspersed with the array of recesses that form a network of cavities within an internal volume of the thermally conductive body. The array of recesses and the array of protrusions define a non-planar interface that is complementary to a curved surface of a heat source. A fluid volume can be retained within the network of cavities at a pressure lower than atmospheric pressure. The heat management device includes a cooling operation mode wherein the fluid volume absorbs heat from the heat source through the non-planar interface and dissipates heat away from the heat source through the network of cavities.