A flow chamber, a cooling system and a method are described. The flow chamber includes an upper chamber including a top wall, an actuator, and a lower chamber. The actuator is located distally from the top wall. The lower chamber receives fluid from the upper chamber when the actuator is actuated. The top wall includes at least one cavity therein. The cooling system utilizes cooling cells including the flow chamber. The method includes driving the actuator at a frequency that directs fluid through the flow chamber.