Heat flow characteristics in the newly developed Wave Heat Sink were analyzed under natural and forced convections by Icepak program using the finite volume method. Temperature distribution and thermal resistance of Wave Heat Sink with/without air vent hole on the top of fin were compared with those of a commercial Al extruded heat sink(Intel Heat Sink). Under the natural convection, the maximum temperature was $45.1^{circ}C$ in the air vent hole typed Wave Heat Sink, which was superior to that of Intel Heat Sink. The thermal resistance was $2.51^{circ}C/W$ in the air vent hole typed Wave Heat Sink, and it changed to $2.65^{circ}C/W;and;2.16^{circ}C/W$ with changes of gravity direction and fin height, respectively. Under the forced convection, the maximum temperature became lower than that under the natural convection. In addition, the thermal resistance lowered in the air vent hole typed Wave Heat Sink with higher fin height and it decreased with increasing the air flux.