Air at 27°C with a free stream velocity of 10 m/s is used to cool electronic Air 111 devices mounted on a printed circuit board. Each device, 4 mm x 4 mm, dissipates 40 mW, which is removed from the top surface. A turbulator is located at the leading edge of the board, causing the boundary layer to be the surface Estimate turbulent. temperature of the fourth device located 15 mm from the leading edge of the board. Turbulator X x = 15 mm Fourth device Printed circuit board.​