Craciunescu O I, Clegg S T
Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA.
J Biomech Eng. 2001 Oct;123(5):500-5. doi: 10.1115/1.1392318.
The effect of blood velocity pulsations on bioheat transfer is studied. A simple model of a straight rigid blood vessel with unsteady periodic flow is considered. A numerical solution that considers the fully coupled Navier-Stokes and energy equations is used for the simulations. The influence of the pulsation rate on the temperature distribution and energy transport is studied for four typical vessel sizes: aorta, large arteries, terminal arterial branches, and arterioles. The results show that: the pulsating axial velocity produces a pulsating temperature distribution; reversal of flow occurs in the aorta and in large vessels, which produces significant time variation in the temperature profile. Change of the pulsation rate yields a change of the energy transport between the vessel wall and fluid for the large vessels. For the thermally important terminal arteries (0.04-1 mm), velocity pulsations have a small influence on temperature distribution and on the energy transport out of the vessels (8 percent for the Womersley number corresponding to a normal heart rate). Given that there is a small difference between the time-averaged unsteady heat flux due to a pulsating blood velocity and an assumed nonpulsating blood velocity, it is reasonable to assume a nonpulsating blood velocity for the purposes of estimating bioheat transfer.
研究了血流速度脉动对生物传热的影响。考虑了一个具有非稳态周期性流动的直刚性血管的简单模型。模拟采用了考虑完全耦合的纳维 - 斯托克斯方程和能量方程的数值解。针对四种典型血管尺寸：主动脉、大动脉、终末动脉分支和小动脉，研究了脉动率对温度分布和能量传输的影响。结果表明：脉动轴向速度产生脉动温度分布；主动脉和大血管中会出现血流逆转，这会使温度分布产生显著的时间变化。对于大血管，脉动率的变化会导致血管壁与流体之间能量传输的变化。对于热学上重要的终末动脉（0.04 - 1毫米），速度脉动对温度分布和血管外能量传输的影响较小（对应正常心率的沃默斯利数下为8%）。鉴于脉动血流速度引起的时间平均非稳态热通量与假定的非脉动血流速度之间差异较小，为了估算生物传热，假定非脉动血流速度是合理的。
