正冻土水热迁移的移动泵模型

通过引入脉冲函数将流量边界条件转化为源（汇）项，冻结锋面处的假想泵从未冻土中抽吸水分并储存在冻结锋面附近的狭窄区域.将水分扩散方程在整体求解域上等效分解为两个方程，避免了处理移动冻融边界的难题.在一个分解方程中引入汇项以表达未冻区水分的流出，在另一个分解方程中引入相同大小的源项以表达冻土中水分的聚集.将移动泵模型相关场方程和变量输入COMSOL Multiphysics模拟软件的数学模块中，对一个封闭系统非饱和土冻结过程中水分和温度的变化过程进行了数值模拟，将模拟结果与前人试验和模拟结果进行了对比.

A moving-pump model for moisture and heat transfer during soil freezing

The pulse function was used to transform the flux boundary condition into the source (or sink)term. An imaginary pump located in the freezing front was sucking water from the frozen zone and storing it in a narrow transition zone near the freezing front.The water diffusion equation was divided effectively into two equations in the whole solving domain to avoid the problem of dealing with the moving interface between frozen and unfrozen zone.A sink term was introduced in one dividing equation to express the discharge of water from the unfrozen zone and a source term was introduced in the other dividing equation to express the gathering of wa-ter in the frozen zone.The field equations and relations between variables were inputted into the mathematical module of the simulation software COMSOL Multiphysics to model a freezing test of an unsaturated soil sample in closed system,and the simulated results was compared with the experimental and simulated results performed by predecessors.