A wake from an elliptic cylinder with fixed separation points is analyzed numerically, and is clarified as follows : An isothermal Karman vortex street never occurs at Re<36, but a cooled Karman vortex street is generated by cooling a progressive wavy wake at 26≤ Re<36, where Re is the Reynolds number. The cooled Karman vortex street can be generated at smaller value of the absolute Richardson number in an elliptic cylinder wake than a circular cylinder wake. By cooling the Karman vortex street, a suppressed flow Is generated. Both the Karman vortex street and the suppressed flow have a double structure combined the motions due to both negative buoyancy and the forced flow. The dominant motion is due to the forced now at the Karman vortex street, and due to negative buoyancy for the suppressed flow. At the boundary between the Karman vortex street and the suppressed now, the dominant motion is exchanged, and the wake frequency and the mean Nusselt number decrease abruptly.