Numerical Analysis of Flow and Heat Transfer in U-tube Under Rolling Motion

The variations of frictional resistance coefficient f and Nu with time in the rolling motion were calculated with Fluent code. The calculating results show that the f and Nu in U-tube in rolling motion fluctuate periodically with time, the oscillating period is the same as the period of rolling motion, and the oscillating amplitude increases with the decrease of rolling period and the increase of rolling amplitude. The maximum and average values of the f and Nu are in direct ratio with the rolling amplitude and angular frequency approximately. The flow resistance and Nu are enhanced in the rolling motion. The effects of rolling motion on the flow and heat transfer in U-tube are significantly different from those in straight tubes.