Abstarct: The flow over open cavities heated with constant temperature from the bottom in a two-dimensionaal horizontal channel has been studied experimentally and numerically. The walls of the channel and the cavity are insulated and the air flow is assumed to be laminar and incompressible. depth of the cavity and inlet length of the channel are equal to H=18 centimeters and exit length of the channel and width of the cavity are equal to 36 centimeters. The flow in the channel has been analysed in three modes of one-section, bisection and trisection cavity and compared experimental results with predictions obtained from a model developed using Fluent. The results show that heat transfer rate from heat source to air flow in the channel is enhanced when number of cavities increase and average air temperature in the cavity decreases. Also the flow in the channel is simulated in varius Reynolds number and Aspect ratio and temperature and flow patterns has been presented.