计算物理 ›› 2009, Vol. 26 ›› Issue (1): 42-48.

• 研究论文 • 上一篇    下一篇

具有表面弛豫的液体自扩散的Monte Carlo模拟

蔡淑惠, 陈巧龙, 蔡聪波   

  1. 厦门大学物理系和通信工程系, 福建 厦门 361005
  • 收稿日期:2007-07-24 修回日期:2008-01-23 出版日期:2009-01-25 发布日期:2009-01-25
  • 作者简介:蔡淑惠(1968-),女,福建,教授,博士,从事磁共振相关研究.
  • 基金资助:
    国家自然科学基金(批准号10575085和10605019);福建省自然科学基金(项目编号2008J0028)资助项目

Monte Carlo Simulation of Liquid Self-diffusion with Surface Relaxation

CAI Shuhui, CHEN Qiaolong, CAI Congbo   

  1. Departments of Physics and Communications Engineering, Xiamen University, Xiamen 361005, China
  • Received:2007-07-24 Revised:2008-01-23 Online:2009-01-25 Published:2009-01-25

摘要: 研究多孔介质中液体的自扩散行为能获得介质的微观结构信息,有助于了解介质中液体的传输性质.以具有不同孔隙大小的无限长圆柱体模型中的液体为对象,采用Monte Carlo随机行走方法,模拟存在表面弛豫时液体的自扩散系数和核自旋磁化强度随时间的变化,导出将NMR弛豫参数和随机行走参数联系在一起的表达式.结果表明:在快扩散区,液体的核自旋磁化强度随弛豫时间呈单指数衰减,且自扩散系数在短时情况下独立于表面弛豫率;在慢扩散区,液体的核自旋磁化强度衰减和自扩散系数在短时情况下均与表面弛豫率无关.模拟结果与理论分析相吻合,可用于求解介质的表面积与体积之比及孔径大小等结构信息.

关键词: 自扩散, 表面弛豫, 磁化强度衰减, Monte Carlo模拟

Abstract: Time-dependent self-diffusion coefficients and magnetization attenuation of liquid with surface relaxation in porous media in an infinitely long cylinder are calculated with Monte Carlo random walk method.Relationship between parameters of NMR relaxation and random walk is obtained.In fast-diffusion area, magnetization of nuclear spins attenuates exponentially,and self-diffusion coefficients are independent of surface relaxivity within short diffusion time.In slow-diffusion area,both magnetization attenuation and self-diffusion coefficients are independent of surface relaxivity within short diffusion time.These results agree well with theoretical analysis.Surfaceto-volume ratio and pore size can be determined.

Key words: self-diffusion, surface relaxation, magnetization attenuation, Monte Carlo simulation

中图分类号: