Numerical simulation of laminar pulsating flow in tubes

In order to investigate laminar pulsating flow characteristics in tubes, a two-dimensional unsteady axisymmetric model was established, and the pulsating fluid with constant wall temperature and periodical variation velocity as the entrance boundary condition of the tube was simulated. The influence of velocity amplitude and frequency on laminar flow was analyzed and the effects of velocity amplitude and frequency on pressure, temperature and wall surface friction coefficient were concluded. Numerical simulation results show that the values of pressure, temperature and wall surface friction coefficient for pulsating flow fluctuate around those of the stable-state flow at the same Reynolds number Re. Phase difference exists between pressure and velocity. The pressure amplitude and the wall surface friction coefficient amplitude are both in direct proportion to velocity amplitude and frequency. The temperature amplitude is in direct proportion to velocity amplitude but inversely proportional to frequency. When the velocity amplitude and frequency are large enough, back flow occurs near the inner surface, and the duration for the back flow increases along with the growing of frequency and amplitude.